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[Interprocess] Named Pipe status
by Geoff Shannon 17 May '13

17 May '13

Hi, I'm interested in writing a named pipe implementation for Boost.Interprocess (mostly since I would like to use it myself!). I was curious if anyone knew if there has already been design work done on a desired interface, or if there is actual work underway (I wasn't able to find any evidence of either but I'm normally just a boost user). Also, any comments/suggestions on what would be desired out of such a feature are much appreciated. thanks, -- Geoff Nothing is ever easy.

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[string_ref] Add an equality operator between string_ref and char*
by Nicola Bizzoca 17 May '13

17 May '13

Hi, string_ref currently lacks of a simple and efficient way to compare a string_ref data to a C style string The current way that string_ref promotes is: string_ref_data.compare("boost(a)lists.boost.org") == 0 It's error prone (always checking for 0, < 0, > 0) and involves a series of implicit casting (from char* to string, and from string to string view) The same it's valid for comparing string_ref to string, but is this case an implicit casting from string to string_ref is much less expensive

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[tti] Will TTI be in 1.54?
by Jeremiah Willcock 17 May '13

17 May '13

Is TTI planned to be in the next release? I have some changes to Boost.Graph that have been in the trunk for a while but depend on TTI to enable backwards compatibility, and it would be nice to have them in a release. Will that be available in the release branch soon so I can test against it? Thank you. -- Jeremiah Willcock

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[config] BOOST_FORCEINLINE for clang
by Vicente J. Botet Escriba 16 May '13

16 May '13

Hi, I would like to add the definition of BOOST_FORCEINLINE for clang when __has_attribute(always_inline) // BOOST_FORCEINLINE ---------------------------------------------// #if !defined(BOOST_FORCEINLINE) # if defined(_MSC_VER) # define BOOST_FORCEINLINE __forceinline +# elif defined(__clang__) +# if __has_attribute(always_inline) +# define BOOST_FORCEINLINE inline __attribute__((always_inline)) +# endif # elif defined(__GNUC__) && __GNUC__ > 3 # define BOOST_FORCEINLINE inline __attribute__ ((always_inline)) # else Could I commit it? Best, Vicente

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determine first arg of callable
by Oliver Kowalke 16 May '13

16 May '13

I need some help to extract the type of a callable which is passed as argument to the ctor of X. struct X { template< typename Fn > X( Fn fn) { ... code which evaluates Fn and extracts the type of the first arg of Fn } }; void f( int) {...} struct A { void operator()( char) {...} void g( string) {... } }; The code should evaluate in the ctor to the arguments of the callables: A a; X x1( f); -> int X x2( a); -> char X x3( bind( & A::g, a, _1) ); -> string I could overload the ctor of X for function pointers: template< typename Arg > X( void(*fn)( Y< Arg > &) ) {...} but how to deal with the other two callable types? result_of and function_traits did not work for me. Oliver

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[Proposal] A little reasonable modification of boost::bind_t
by Arthur Athrun 16 May '13

16 May '13

Hi, everyone, I'd like to propose a little modification of boost:: bind to expose more information in boost:: _bi:: bind_t. Here is my motivation problem. Suppose this is a function which takes boost: :_bi::bind_t as a parameter. But at the same time, I'd like to enumerate all binded parameters and do something for specific types, like the following pseudo code shows. template< class F> void foo(F & f) { foreach(T& arg, f.arguments()) { if(boost::is_same<T, ID_t>::value) //here ID_t is a user specific type //do something for arg. } } I found that all binded arguments are stored in a listN object. But unfortunately, the list object (L _l in boost::_bi::bind_t) is set to private access and there is no method to boost::_bi::bind_t to access the listN object and the type of listN. I don't know why you developers didn't provide a method to access the listN object. But it seems reasonable to provide a public method in <boost\bind\bind_template.hpp>, like this typedef L argu_type; const L & arguments() const {return l_;} Also, the class "template<class T> class value" in <boost\bind.hpp> doesn't provide any access to T. It will be reasonable to add access of type T, like this public: typedef T val_type; With such modifications, we can access all binded arguments in the boost::_bi::bind_t. Here is a showcase. template<class T, class VT>void Test(VT t, T * p = 0) { //This parameter is not binded, so ignore it! }template<class T, class VT>void Test(VT t, typename T::val_type * p = 0) { //T::val_type is the parameter's type， //and can use boost::is_same<T::val_type, ID_t>::value to check it! std::cout<<"great! we get a value here!"<<t.get()<<std::endl; } template <class R, class F, class A1, class A2>void retrive_args(boost::_bi::bind_t<R, F, boost::_bi::list2<A1, A2> > & f) { Test<A1>(f.arguments()[_1]); Test<A2>(f.arguments()[_2]); } int f(int a, double b) { std::cout<<a<<std::endl; return a; } int main(int argc, char * argv[]) { double t = 1.0; retrive_args(boost::bind(f, _1, 0.2)); //Here will retrive the second parameters only. return 0; } I don't know if I get the right way to implement it. Please let me know if you have another implementation. Any comments or ideas will be appreciated. Thanks. -- Athrun Arthur Cluster and Grid Computing Lab (CGCL) Services Computing Technology and System Lab (SCTS) School of Computer Science and Technology (CS) Huazhong University of Science and Technology (HUST) Wuhan, 430074, China EMail:athrunarthur@gmail.com

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[spirit][lex] remove_referece necessary for lex::less
by Andreas Pokorny 14 May '13

14 May '13

Hi, Can I apply that patch? Index: boost/spirit/home/lex/lexer/support_functions.hpp =================================================================== --- boost/spirit/home/lex/lexer/support_functions.hpp (revision 84231) +++ boost/spirit/home/lex/lexer/support_functions.hpp (working copy) @@ -47,11 +47,13 @@ template <typename Env> struct result { - typedef typename - remove_const< - typename mpl::at_c<typename Env::args_type, 4>::type - >::type - context_type; + typedef + typename remove_reference< + typename remove_const< + typename mpl::at_c<typename Env::args_type, 4>::type + >::type + >::type + context_type; typedef typename context_type::base_iterator_type type; };

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Re: [boost] Embedding manifest into the regression tests (was: [testers] [log] Problems with tests)
by Holger Grund 14 May '13

14 May '13

VC++ 10 and 11 dont use sxs isolation for runtime libs any more. IOW, you dont need a manifest for the CRT in VS2010&2012. Regards -hg Sent from Samsung MobileAndrey Semashev <andrey.semashev(a)gmail.com> wrote:On Monday 13 May 2013 20:39:21 Daniela Engert wrote: > Am 13.05.2013 19:50, schrieb Andrey Semashev: > > On Monday 13 May 2013 16:06:01 Sergey Cheban wrote: > >> [snip] > >> The bjam scripts embed the manifest into the executable if it was > >> generated by the linker. And the linker generates the manifest by > >> default if the /manifestdependency option was specified. > >> > >> May be, it is reasonable to add the "/MANIFEST" to the linker options > >> explicitly. > > > > I know little about Windows manifests, but if I'm not mistaken, > > /manifestdependency describes the dependency to be put in the manifest and > > /MANIFEST only tells the linker to generate the .manifest file. If MSVC 10 > > and 11 removed their /manifestdependency then what should be put into the > > manifest? > > Is this really about dependency? In Visual Studio, MSBuild is configured > to insert this into .exe link options by default: > > /MANIFEST /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /manifest:embed From MSDN ([1], [2]) this seems to be the default, if manifest is generated. I'm not sure what is the problem with manifests as it seems it should be generated by default. So either it is not generated when there are no /manifestdependency entries or I'm missing something. I hope someone with more experience can comment on this. [1] http://msdn.microsoft.com/en-us/library/f2c0w594.aspx [2] http://msdn.microsoft.com/en-us/library/bb384691.aspx _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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[smart_ptr] lost doc link to enable_shared_from_this
by Kim Barrett 14 May '13

14 May '13

In boost 1.53 I can't find any reference to the documentation forenable_shared_from_this. The documentation page exists: http://www.boost.org/doc/libs/1_53_0/libs/smart_ptr/enable_shared_from_this… but I can't find any reference to it from anywhere in the smart_ptr / shared_ptr documentation. As late as boost 1.52 there was a reference to it in a note for the template<class Y> explicit shared_ptr(Y * p); constructor, but that note was removed in boost 1.53, and there doesn't seem to be any other reference to enable_shared_from_this. One of the places I expected to find a reference to enable_shared_from_this was the "Programming Techniques" page's entry "Obtaining a shared_ptr from a raw pointer", but I found no mention of it there through boost 1.53.

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[endian] Boost licensed detail/endian.hpp [was: [1.54.0][release] Provisional schedule]
by Beman Dawes 14 May '13

14 May '13

>On Mon, May 6, 2013 at 9:06 AM, Daniel James <daniel(a)calamity.org.uk> wrote: > >> On 6 May 2013 14:15, Philip Bennefall <philip(a)blastbay.com> wrote: >> > I was just wondering if it is possible to get a modified, Boost licensed >> > version of detail/endian.hpp into this next release? It'd be great to get >> > this licensing issue resolved in this next Boost version, if at all >> > possible. >> >> I don't know. I haven't been following that. Did anyone take >> responsibility for it? >> > >It's highly unlikely. There is al alternative implementation in Boost >Predef. But that isn't even fully accepted as a library. I could attempt to >do a standalone port from Predef into detail/endian.hpp but I doubt I could >both get it done and tested to a point that it would be safe to merge into >release. I'm restarting work on the boost endian library, so I'd be willing to take this on. If you send me your Predef port of detail/endian.hpp, I'll see if I can move it along. No promises until I see what you have, however. Thanks, --Beman

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Can anyone take a quick read of an array type?
by Daryle Walker 14 May '13

14 May '13

I banged out a little something at <https://github.com/CTMacUser/ArrayMD>. The "boost::container::array_md<T, N>" class template can be used like the (C++11) std::array. It has the same members (value_type, size_type, difference_type, reference, const_reference, pointer, const_pointer, iterator, const_iterator, reverse_iterator, const_reverse_iterator, at, front, back, operator[], data, begin, cbegin, end, cend, rbegin, crbegin, rend, crend, empty, size, max_size, fill, and swap). It has external functions operator==, operator!=, and swap. It fulfills the Container and Reversible-Container archetypes, with random-access iterators. It lacks: * support for 0 as the length. It combines the type and extent directly as the internal array's type expression, so the compiler will complain if zero-length arrays are used. (You also can't use a function type, reference, or class-type that's marked abstract as element types.) But front, back, and data will always be valid. * The ordered-comparison operators (<, >, <=, and >=). * The get access function, plus helper specializations for std::tuple_size and std::tuple_element. It adds: * 3 class-static constants: dimensionality (= 1), static_size (= N), and static_sizes (a one-element array with value N). * 2 type aliases: direct_element_type (= value_type) and data_type (= direct_element_type[N]). * If value_type is an array type, fill still works, by doing assignments at the inner non-array level. * The apply member functions, that call a function over each element, including the element and its index coordinate with each call. * operator(), which works just like operator[]. * As many member functions work with constexpr and/or noexcept as possible. Array_md is an aggregate type. It is trivially-copyable, trivial, standard-layout, and/or POD if the element type is. It has default-, copy-, move-construction, destruction, copy-, and/or move-assignment if the element type does. (Default-initialization follows the element type's lead if its code-ful or random garbage bits.) Initialize it like a structure with a single member object of type data_type. Indicated by the "md" suffix, the array modeled by this class template can be multi-dimensional. Unlike C-level arrays, which are all nested one-level arrays, this class template lets you express multi-dimensionality flatly. And the arguments are compatible with the comma-separated lists used in variadic stuff. When you add another extent M (BEFORE the others): * ++dimensionality * static_size *= M * static_sizes -> { old static_sizes, M } * direct_element_type = old data_type * data_type = direct_element_type[ M ] * The apply method sends the remote function each element along with all of its index coordinates (dimensionality + 1 arguments total). * operator[] still takes one argument, and returns a direct_element_type&. You can continue to chain-index to the element type just like nested built-in arrays. * operator() and at can take as many arguments as dimensionality. Using that many indices gives an element, using less gives a reference to an intermediate array (which you can use the built-in operator[] on). If you use no indices, then you get a reference to the entire implementation C-level array returned. (I originally had operator() put in since operator[] can't handle multiple direct arguments.) You can crank the recursion backwards, and have an array with no extents. Such a type supports one element (NOT zero, since one is the multiplicative identity). That's another reason not to special-case zero-value extents in, to keep the size non-decreasing with new extents. This degenerate case doesn't support static_sizes (since it would be an illegal zero-length array) or operator[] (since there's no array member object). Added late to the cycle: When perusing the C++11 standard, I noticed that operator[] can take a std::initializer_list argument, although the core language never uses it; it's only for UDTs. I added support for that. I added support for it in the operator() and at methods, for symmetry. The length of the list must equal dimensionality. To-do: Should I implement get, tuple_size, tuple_element, and the ordered-comparison operators? They're very linear-oriented. I'm not sure they're used that much. And I'm not sure what they would even mean for a non-linear container; I may have to apply some sloppy linearity for them to be defined. (I don't think I could make them (get, tuple_size, and tuple_element) multi-coordinate; then they couldn't work with generic code.) I was trying to avoid any linearity, and depend on apply for iteration-related tasks. Then I decided to support the range-for statement. Then it looked weird to have a sloppy & minimal begin/end tacked on, so I put in a full iteration set. Then at that point, I put in so many things like std::array that I put everything else in so they could have source compatibility. (BTW, there are several utility/helper classes and functions. Some are in separate headers, the others near the start of "array_md.hpp".) Versus Boost.MultiArray: (This is from a quick look at BMA.) BMA statically declares the element type and the number of dimensions; the actual extent values (and therefore the element count) and the elements themselves are determined/allocated at run-time. It's like std::vector vs. std::array, the former is more powerful, but may be overkill that limits compile-time opportunities, while the latter can take advantage of compile-time optimizations and can shift memory usage from the heap to the stack. Versus Brian J Smith's Array (at <https://github.com/BrianJSmith/Array>), on the review queue: * (Used to support extent values of 0, but has been removed). * Requires at least one extent, while array_md supports 0 extents. * Implements multi-dimensions as maps::array objects nesting each other, similar to how C-level arrays are made multi-dimensional. The array_md model computes the nested C-level array type and stores that directly. This has big consequences, because of padding. Class types may add padding bytes before(?), between, and after their non-static member data sub-objects. Built-in array types never have padding. So maps::array may end up with lots of padding bytes scattered through it, while array_md has one set of padding and its elements contiguous. This makes implementing the data method possible; it can't work with maps::array unless we get lucky and the compiler doesn't add any padding. (The data method isn't provided by maps::array anyway; the "data" name is used differently.) * Due to the above, maps::array matches nested C-level arrays in that range-for iterates over the immediately-lower level of elements. This is OK when dimensionality is 1, but higher dimensions can't dig into the element type through range-for. The array_md class's range-for support is at the element level, due to being able to define the data method. * There are operators * (unary) and + (binary) overloads. They seem more for iterators than containers; then I figured out that he's simulating the effects of array-to-pointer conversions, which make these operations possible. That decay action is something we shouldn't be exalting. (And there isn't a reversed version for offset + container.) * There's no option to input all the indices at once for "at," instead maps::array needs to chain them. (There's no throw-less version called operator(), needed due to operator[] being limited to one argument.) (There's no initializer-list variants either; but the maps::array code has no C++11 features besides variadic templates.) * There is stream-output code. * There is ordered-relations operator (< > <= >=) code. * Revealing the values for the dimensions outside of the template header differ. * Actually has documentation, as opposed to Doxygen comments. Daryle W.

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[testers] [log] Problems with tests
by Andrey Semashev 14 May '13

14 May '13

Hi, I'm looking at the recent trunk test results (http://www.boost.org/development/tests/trunk/developer/log.html) and seeing a few failures that I cannot explain or reproduce. In particular: 1. RDC-VC10 fails with errors that were fixed quite some time ago (in revision 83986 and the test results correspond to 84238). The headers in the errors are not included in the test code and other testers do not show these errors. I suspect that the tester has some problems regarding SVN checkout or maybe cleaning the previous test results. 2. There are a few testers that fail the util_dynamic_type_dispatcher and util_static_type_dispatcher tests, namely Qt5 jc-bell.com, teeks99-01a- win7-32on64 and DrWeb_x86. The test report says this is a runtime failure but it has no output or just has an exit status. The same tests run successfully for other testers, as well as in my local runs. It may be worth noting that the same code is indirectly tested with other tests (e.g. form_attr and filt_attr) and these tests succeed. I would appreciate any help in researching the problem with these tests. Are there any errors that are not present in the report? Does it crash (what's the backtrace)? Any configuration error (missing libraries)? Thanks.

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Default x86 instruction set
by Andrey Semashev 13 May '13

13 May '13

Hi, I noticed that by default x86 32 bit builds are targeted for i386 (at least gcc toolset and its derivatives explicitly specify -march=i386 in the command line). Is there a reason to target for such an ancient instruction set by default? Frankly, I'm not sure that the current Boost code would even run on a real 80386, since there are at least quite a few places with atomic operations, which I think were not present on that CPU. Also, I would like to use cpuid safely in my library, and this operation appeared only in some i486 and all Pentiums, so I would basically target my code for Pentium at the very least. But perhaps we could raise the default to Pentium Pro (i686)? Most Linux distributions already switched to this target for 32 bit builds because of availability of cmov instructions. Windows and OS X, I think, don't support older architectures either.

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Embedding manifest into the regression tests (was: [testers] [log] Problems with tests)
by Sergey Cheban 13 May '13

13 May '13

On 13.05.2013 13:23, Andrey Semashev wrote:> On Mon, May 13, 2013 at 12:58 PM, Sergey Cheban <s.cheban(a)drweb.com> wrote: >> The problem is related to the fact that MS Windows (at least, Windows >> Server 2012) requires elevation for the execulables with names that >> match the *patch*.exe mask. So, util_dynamic_type_disPATCHer and >> util_static_type_disPATCHer require elevation. > lol, what a wonderful and obvious security policy on MS part, isn't > it? :) I've found that the same tests succeeded for the msvc-9.0 toolset. It is because the manifest file is generated for this toolset. I've found that the "C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include\crtdefs.h" file contais the following: =============================================== #pragma comment(linker,"/manifestdependency:\"type='win32' " \ "name='" __LIBRARIES_ASSEMBLY_NAME_PREFIX ".DebugCRT' " \ "version='" _CRT_ASSEMBLY_VERSION "' " \ "processorArchitecture='x86' " \ "publicKeyToken='" _VC_ASSEMBLY_PUBLICKEYTOKEN "'\"") =============================================== and the "C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\crtdefs.h" and "C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include\crtdefs.h" contain no such code. The bjam scripts embed the manifest into the executable if it was generated by the linker. And the linker generates the manifest by default if the /manifestdependency option was specified. May be, it is reasonable to add the "/MANIFEST" to the linker options explicitly. Btw, I see the following in the msvc.jam: ================================================ if [ MATCH ^([67]) : $(version) ] { .... } else { .... # Make sure that manifest will be generated even if there is no # dependencies to put there. toolset.flags $(toolset).link LINKFLAGS $(conditions)/<embed-manifest>off : /MANIFEST ; } ================================================ -- Sergey Cheban

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Re: [boost] Live read-only GIT mirrors of Boost trunk SVN
by Niall Douglas 13 May '13

13 May '13

> on Thu May 09 2013, Niall Douglas <ndouglas-AT-blackberry.com> wrote: > > Just to be clear and for the record, I have no compelling arguments, > > no plan for migration, and I am in no way criticizing your work, your > > leadership, nor suggesting the throwing away of any planning or > > coding. I apologise unreservedly if anything in my words appeared that > > way. I am absolutely sure that you have given this the very deepest of > > thought and I - as always actually - trust your judgment. I am simply confused. > > OK. I don't know how to un-confuse you, though, sorry. > [snip] > Unfortunately for my workload, the community begs to differ. The lightbulb has switched on: I had been confused because I had thinking the migration was based on technical arguments. I now realize the arguments are mostly non-technical, so I am now deconfused. Thanks for the illumination. > > We can talk about this at C++ Now next week, but if we were to > > coordinate our efforts and I have definite approval and support from > > Boost SC, I have no objection to volunteering for this. > > I don't see what difference approval from the steering committee makes. > If you think it would be helpful, you can go ahead. A two way mirror would need changes to the main Boost SVN installation. Changes which could lose data and cause outages. It's not something I'd proceed with without unanimous support, especially for moral support if data loss did occur. > > That probably is unacceptable to you given your apparent plans. > > Yeah, we want to get this thing over with. Thanks for the suggestions, though. I understand entirely now. Sorry it took a while. Do get in touch if you need it. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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Re: [boost] Git Modularization Ready for Review
by Niall Douglas 13 May '13

13 May '13

> It's a question of degree. Daniel et. al.'s recent work shows that you > can keep that loss pretty low. "Where there's a will there's a way?" Agreed. With enough effort anything is possible. But tough on those tasked with the grunt work. > >> What happens in a few years time when Git is replaced with the next big > > thing? > >> Do we lose the history again? And then again when that gets replaced too? > > > > That's exactly what happens. Bitrot is always inevitable in the long run. > > Here call it "non-fatal bitrot" :) > > > > My only red line is corruption of past and present source code releases. It > > must *always* be possible to check out tag X and build release X. > > So why have a VCS at all? Named tarballs meet your red line. VCS is for workflow and collaboration. Optionally for blaming bugs through automated regression analysis. They can be useful for generating some interesting stats. And yes, I do use named tarballs (or ZFS snapshots more recently) of the VCS store exactly for history preservation. VCSs aren't for history preservation, especially as they're usually not bitrot tolerant. > > Well, the Git way of helping stuff get out of step is that everyone gets > > their own full copy of the whole repo, and their copy is just as important > > as anyone else's copy. You clone, you develop and test, and optionally push > > changes elsewhere which could be your friend, your team, your employer, or > > of course some central authoritative copy. > > That works for a monolithic project. Boost is not monolithic but it's > single repo model was forcing it to act like one. As well as making > life a little easier for library developers, the modularisation effort > should help end users too. For a while now people have been wanting to > take only what they need from Boost and ignore the rest. It's > especially important in commercial environments where manager (rightly > or wrongly) are reluctant to depend on huge quantities of unreviewable > code with unknown interactions. Modularisation won't solve the problem > overnight but it helps. I disagree with pretty much all of this. And I think modularization, as currently proposed if I understand it correctly, actually makes those feared interactions much worse and/or much more work to avoid. > > So I'm afraid I just don't get the present design for a library as > > small and as tightly integrated as Boost. > > You must be talking about some other Boost. It's all subjective. I agree there are a chunk of Boost libraries which are fairly standalone and I have no problem with those being turned into git submodules. > > I'm a great believer in refusing to let programmers commit code which breaks > > other code rather than nagging them later to fix an earlier commit. The > > point of failure notification ought to be as close to cause as > > possible. > > Surely the developer sees the breakage the moment they update the > versions of the other libraries they are working against. And then they > can fix it at their leisure while early adopters get to use their code > with the previous version of the conflicting library. My point is this isn't automatic. It requires programmers not to be lazy. That hasn't been hugely successful in the past. > When you are talking about breakages are you talking about merge > conflicts or compile/test-failures? Up till now I've assumed you mean > the latter. But now I'm thinking you might be asking what happens if > the developer of library X makes a change to header H and developer Y > also makes a change to _the same header_? No that's easily detectable. My concern is when modifications to submodule A and submodule B cause arbitrary C in some submodule D to suddenly fail. > The way the modularisation works, I'm not even sure this is possible. > The libraries are meant to be self-contained so you only ever change > your own headers. It's a good question and one I hand't thought about. > Perhaps the people working on this can weigh in here. Git submodules are too loosely coupled for anything but loosely coupled, fairly standalone libraries. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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[chrono/date] name of getters - error: changes meaning of
by Vicente J. Botet Escriba 13 May '13

13 May '13

Hi, Naming the getters with the same name as the type chrono::year year() const; results in a lot of error with gcc <= 4.8.0 ../../../boost/chrono/date/ymd_date.hpp:267:7: erreur: declaration of ‘boost::chrono::year boost::chrono::ymd_date::year() const’ [-fpermissive] ../../../boost/chrono/date/year.hpp:36:11: error: changes meaning of ‘year’ from ‘class boost::chrono::year’ [-fpermissive] When I add -fpermissive I get yet the warning ../../../boost/chrono/date/year.hpp:36:11: attention : changes meaning of ‘year’ from ‘class boost::chrono::year’ [-fpermissive] Do someone how to get ride of this warning/spam? In addition, no way to make it working with gcc-4.2.1. No issue with clang-3.1, 3.2. Not checked with msvc. Is this a bug on gcc? Best, Vicente

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[chrono/date] class names
by Vicente J. Botet Escriba 13 May '13

13 May '13

Hi, I would like to fix the names of date classes for the different representations. I'm not saying that all the representations need to be provided for a first release. Here it is my proposal. The following are unchecked and non contextual dates classes * calendar_date: field based representation of year + month + day. * serial_date: days based representation * ordinal_date: field based representation of year + day_of_year * week_date: field based representation of year + week + weekday Checked dates classes names just add a checked_ prefix to the corresponding unchecked date classes. * checked_calendar_date: field based representation of year + month + day. * checked_serial_date: days based representation * checked_ordinal_date: field based representation of year + day_of_year * checked_week_date: field based representation of year + week + weekday We can also have an alias date template <typename Tag = serial, validity=validity::unchecked> class date; so that date<calendar> ~ calendar_date date<serial> ~ serial_date date<> ~ serial_date ... I'm, open of course, to other defaults for these parameters, if the idea of an alias is accepted. For the time been a single contextual date class should be enough, as all the contextual information is relative to the year/month/day representation. * contextual_date: field based representation of year + month + day + context-meta-data Comments, critics and suggestions are welcome. Best, Vicente

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[any][quickbook] Recent compile failure gcc vs. clang..
by Rene Rivera 13 May '13

13 May '13

Not sure when this started failing other than it was some time this past week.. ===== Froggy:quickbook grafik$ pwd /Users/grafik/devroots/Boost/trunk/tools/quickbook Froggy:quickbook grafik$ b2 toolset=clang ...patience... ...patience... ...found 1735 targets... Froggy:quickbook grafik$ b2 toolset=darwin ...patience... ...patience... ...found 1735 targets... ...updating 3 targets... darwin.compile.c++ ../../bin.v2/tools/quickbook/src/darwin-4.2.1/release/link-static/quickbook.o ../../boost/any.hpp: In function ‘ValueType boost::any_cast(boost::any&) [with ValueType = const int&]’: ../../boost/any.hpp:308: instantiated from ‘ValueType boost::any_cast(const boost::any&) [with ValueType = const int&]’ ../../boost/program_options/variables_map.hpp:69: instantiated from ‘const T& boost::program_options::variable_value::as() const [with T = int]’ src/quickbook.cpp:387: instantiated from here ../../boost/any.hpp:292: error: forming reference to reference type ‘const int&’ ../../boost/any.hpp:294: error: forming reference to reference type ‘const int&’ ../../boost/any.hpp: In function ‘ValueType boost::any_cast(boost::any&) [with ValueType = const std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&]’: ../../boost/any.hpp:308: instantiated from ‘ValueType boost::any_cast(const boost::any&) [with ValueType = const std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&]’ ../../boost/program_options/variables_map.hpp:69: instantiated from ‘const T& boost::program_options::variable_value::as() const [with T = std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >]’ src/quickbook.cpp:421: instantiated from here ../../boost/any.hpp:292: error: forming reference to reference type ‘const std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&’ ../../boost/any.hpp:294: error: forming reference to reference type ‘const std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&’ ../../boost/any.hpp: In function ‘ValueType boost::any_cast(boost::any&) [with ValueType = const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&]’: ../../boost/any.hpp:308: instantiated from ‘ValueType boost::any_cast(const boost::any&) [with ValueType = const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&]’ ../../boost/program_options/variables_map.hpp:69: instantiated from ‘const T& boost::program_options::variable_value::as() const [with T = std::basic_string<char, std::char_traits<char>, std::allocator<char> >]’ src/quickbook.cpp:438: instantiated from here ../../boost/any.hpp:292: error: forming reference to reference type ‘const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&’ ../../boost/any.hpp:294: error: forming reference to reference type ‘const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&’ ../../boost/system/error_code.hpp: At global scope: ../../boost/system/error_code.hpp:222: warning: ‘boost::system::posix_category’ defined but not used ../../boost/system/error_code.hpp:223: warning: ‘boost::system::errno_ecat’ defined but not used ../../boost/system/error_code.hpp:224: warning: ‘boost::system::native_ecat’ defined but not used "g++" -ftemplate-depth-300 -O3 -finline-functions -Wno-inline -Wall -gdwarf-2 -fexceptions -g0 -DBOOST_ALL_NO_LIB=1 -DBOOST_DETAIL_CONTAINER_FWD -DBOOST_FILESYSTEM_NO_DEPRECATED -DBOOST_FILESYSTEM_STATIC_LINK=1 -DBOOST_SYSTEM_STATIC_LINK=1 -DNDEBUG -I"../.." -c -o "../../bin.v2/tools/quickbook/src/darwin-4.2.1/release/link-static/quickbook.o" "src/quickbook.cpp" ...failed darwin.compile.c++ ../../bin.v2/tools/quickbook/src/darwin-4.2.1/release/link-static/quickbook.o... ...skipped <p../../bin.v2/tools/quickbook/src/darwin-4.2.1/release/link-static>quickbook for lack of <p../../bin.v2/tools/quickbook/src/darwin-4.2.1/release/link-static>quickbook.o... ...skipped <p../../dist/bin>quickbook for lack of <p../../bin.v2/tools/quickbook/src/darwin-4.2.1/release/link-static>quickbook... ...failed updating 1 target... ...skipped 2 targets... ===== Seems some of the std::any conformance changes broke for the GCC included in the Xcode 4.6.2. -- -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim - grafikrobot/yahoo

4 6

Re: [boost] [config] BOOST_FORCEINLINE for clang
by Daryle Walker 13 May '13

13 May '13

I didn’t know that the GCC emulation went that deep. Anyway, I think that Clang should eventually wean away from being a GCC copycat, and that comment would be necessary. And if that doesn’t happen, another maintainer may wonder about Clang support, not knowing the details on Clang’s GCC emulation, and seeing the comment will save a trip to this mailing list. Sent from Windows Mail From: Mathias Gaunard Sent: ‎Monday‎, ‎May‎ ‎13‎, ‎2013 ‎5‎:‎45‎ ‎AM On 13/05/13 07:12, Daryle Walker wrote: > You should include a comment in the GCC section that it also works for Clang, > due to Clang's GCC emulation. That way, later maintainers won't be wondering > if Clang support should be added. (And help debugging if Clang ever stops > emulating GCC by default.) Isn't it common knowledge that Clang is compatible with GCC and pretends to be GCC 4.2, and that therefore most GCC-specific code will just work with Clang out of the box?

1 0

boost modularization questions
by Eric Cornelius 13 May '13

13 May '13

Hi all, Out of curiosity, is the plan to move to a git pull-request model once the modularization process is complete? Or is github being used simply as a convenient mirror and interface for browsing code and history? Also, I have some changes to the Jamroot and boostcpp.jam files for improving modularization builds, which aggregate all the public headers from modules into the standard boost/... layout within the install/include directory, as well as implicitly setting up include paths during the initial build process. https://github.com/EricMCornelius/boost/commit/cdc08a1afa4b3df85997d54d9e6a… Cheers, Eric Cornelius

3 2

Boost range - Add variadic join/zip
by Gonzalo BG 12 May '13

12 May '13

Code available here: https://gist.github.com/gnzlbg/5547905 Let, std::array<double,4> a = {{ 1, 2, 3, 4 }}; std::list<int> b = { 11, 22, 33, 44 }; std::deque<int> c = { 111, 222, 333, 444 }; std::vector<int> d = {1111,2222,3333,4444 }; If the values stored in a container have the same type, I would like to iterate over different containers as if it were a single one, and: /// - modify its value for(auto&& i : join(b,c,d)) { i += 1; } /// - use it with boost algorithms boost::transform(join(b,c,d),begin(join(b,c,d)),[&](int j){ return j * 2; }); /// - and read it for(const auto& i : join(b,c,d)) { std::cout << i << "\n"; } Another problem I usually face is manipulating data that has different types. This data is usually stored in different containers for efficiency, but it does belong together. Zip can be used to iterate throw a row of this kind of table-like data structure: for(const auto& t : zip(a,b,c,d)) { std::cout << t << "\n"; } However, boost's zip_iterators are not writable. I don't really think it would be possible to make them writable, but that would allow code like this: typedef decltype(*begin(zip(a,c,d))) tIt; boost::sort(zip(a, c, d), [](const tIt& i, const tIt& j){ return boost::get<0>(i) > boost::get<0>(j); }); which sorts the three containers in lock-step after the values in the first container (a). Some parts of this code can be implemented with minor extensions to boost range. A variadic join might look like this: template<class C> auto join(C&& c) -> decltype(boost::make_iterator_range(c)) { return boost::make_iterator_range(c); } template<class C, class D, class... Args> auto join(C&& c, D&& d, Args&&... args) -> decltype(boost::join(boost::join(boost::make_iterator_range(std::forward<C>(c)), boost::make_iterator_range(std::forward<D>(d))), join(std::forward<Args>(args)...))) { return boost::join(boost::join(boost::make_iterator_range(std::forward<C>(c)), boost::make_iterator_range(std::forward<D>(d))), join(std::forward<Args>(args)...)); } A variadic zip is more complicated. If we want write access we cannot use boost zip_iterator. Still one can use Anthony Williams' TupleIterator: template <class... T> auto zip(T&&... c) -> boost::iterator_range< decltype(iterators::makeTupleIterator(std::begin(std::forward<T>(c))...))> { return boost::make_iterator_range (iterators::makeTupleIterator(std::begin(std::forward<T>(c))...), iterators::makeTupleIterator(std::end(std::forward<T>(c))...)); } For read-only access one could use boost::zip_iterator, but I think write-access is _really_ important (e.g. sort wouldn't work). Would it be possible to add similar functionality to boost range? This code wouldn't work without the help of everyone who participated in the following SO discussions: - http://stackoverflow.com/questions/14366576/boostrangejoin-for-multiple-ran… - http://stackoverflow.com/questions/13840998/sorting-zipped-locked-container… and without Anthony Williams's tupleIterator. See also http://www.justsoftwaresolutions.co.uk/articles/pair_iterators.pdf Bests, Gonzalo BG

5 9

[chrono/date] conversion between concrete dates
by Vicente J. Botet Escriba 12 May '13

12 May '13

Hi, as the conversion between concrete dates could be expensive I guess that these conversion must be explicit. But this has some consequences when used the implicit conversion was hidden a not efficient implementation, e.g. date ISO_week_start = mon <= jan/day(4)/y; jan/day(4)/y should be ymd_date as is the efficient representation. The date generator was declared as date operator<=(weekday wd, date x); but it works efficiently only for days_date. If we provide only the functions that are efficient we should declare it as days_date operator<=(weekday wd, days_date x); So the preceding expression would need an explicit conversion days_date ISO_week_start = mon <= days_date(jan/day(4)/y); Do we want to go on this direction? A radical alternative to the explicit construction, if we want to make evident that the conversion operation could be expensive, is to use a compute_ factory days_date ISO_week_start = mon <= compute_days_date(jan/day(4)/y); Best, Vicente P.S. the generator function is just an example needing explicit conversion.

4 18

[spirit] [lex] semantic actions to handle and manipulate eoi
by Andreas Pokorny 12 May '13

12 May '13

Hi, I want to replace a flex lexer with boost.spirit.lex. We implemented an include-like functionality inside the lexer semantic actions: include { BEGIN(incl) } <EOF> { leaveCurrentFile(); popScannerState(); } <incl> { ".+" { openNewFile(); pushScannerState(); BEGIN(INITIAL); } } Is there a way to do that in lexertl? I thought about extending the spirit file_iterator but found that unwieldy. So I now consider adding a semantic actions that are allowed to change lex::_eoi and the ability to have a eoi token or just a semantic action to handle eoi. Is that a reasonable way of implementing that? regards Andreas

1 0

[1.54.0][release] Provisional schedule
by Daniel James 12 May '13

12 May '13

Hello everyone, I've put up a provisional schedule for the next release on the calendar. You can see it at: http://www.boost.org/development/ It targets a 1st July release date, and follows the usual schedule relative to that date. The deadlines for the release branch are pretty soon, particularly the deadline for new libraries which is just a week away. Also, the deadline for new features is just after C++Now. If any of this is a problem let us know now. The release after that will probably target November 1st (as normal), which will give a 4 month release cycle. If the git modularization is considered ready, this will allow a little extra time to deal with any disruption caused (possibly not enough...). How does that sound? Any thoughts? Daniel

9 34

[GSOC] XML library of Boost
by Amos Ji 12 May '13

12 May '13

Hi All, I'm a graduate student from Fudan University in China. And I hope to contribute some code to Boost during the GSOC. I've scanned the idea page. The ideas in the page are all very interesting and challenging. But what I'm interested in most is XML library, which is at the bottom of page. I think the XML format is the most popular standard for storing information so it's important for Boost to have a good XML library. However, I know Boost contains RapidXML in property_tree library to parse XML file. So what I want to make sure is I need to implement a new XML parser in this project instead of make enhancement for RapidXML. Am I correct? If so, I have some ideas to share with you. In my opinion, an XML parser must be able to do these things: 1. To Iterate over DOM nodes tree; 2. To access the values of nodes and their attributes quickly; 3. To insert or delete nodes or attribute of an exact node easily; 4. To generate new XML from the structure which stores XML in the library. And there are some optional function too: 1. To support XPATH; 2. To validate whether the XML file is valid; 3. To support various encoding; 4. To manage memory better; 5. To support regular expression. The ideas are not mature now. I'll improve them in my proposal. In fact, it's not easy to implement a perfect XML parser but I'll do my best. And I have another question. Who will mentor this XML library project? Thanks for your patience to read this email. Sincerely, Mingchao -- Amos Ji(Mingchao Ji) Master in School of Information Science and Engineering, Fudan University MSN: jmc891205(a)hotmail.com E-mail: jmc891205(a)gmail.com

14 36

[type_erasure] How to have just one behavior from relaxed without inheriting the other behaviors
by Felipe Magno de Almeida 12 May '13

12 May '13

Hello, I need to create a type_erasure::any with just this behavior from relaxed: copy assignment of any uses the copy constructor if it can't use assignable(either because assignable is missing, or because the stored types do not match). But without adding the other behaviors, is there a way to implement this? Regards, -- Felipe Magno de Almeida

2 1

[math][constants] mathematical constants page deserves to be more visible in the documentation
by Andrew Hundt 11 May '13

11 May '13

I believe the Boost.math toolkit mathematical constants are an extremely useful feature, yet it is extremely difficult to find. Every time I try to browse to it I try searching boost.org/libs, then try the math library page and cannot find the links at either of those locations. In fact, I'm not exactly sure how to browse to it and instead use saved bookmarks. I it would be worthwhile if there was some direct link or mention of it on boost.org/libs/math at minimum, and possibly even directly on boost.org/libs . Here is the mathematical constants page I am referring to: http://www.boost.org/doc/libs/release/libs/math/doc/sf_and_dist/html/math_t… Any thoughts on this idea? Cheers! Andrew Hundt

5 7

Re: [boost] Live read-only GIT mirrors of Boost trunk SVN
by Niall Douglas 11 May '13

11 May '13

> on Mon May 06 2013, Niall Douglas <ndouglas-AT-blackberry.com> wrote: > > > My experience with SubGit has been very, very good. I would *strongly* > > recommend it over git2svn. > > Why, have you got a lot of experience with both tools? You'd recommend > SubGit for what job, exactly? Does it modularize? (answer: no). Git2svn is painful. I think anyone who has used it even trivially has found it so. SubGit can map structure arbitrarily, so SVN branches need not become GIT branches, they can become tags or any other kind of git ref. You can apply filters and map one (or more) SVN repo to multiple output GIT repos using those filters, so yes it does do limited modularization. Is that modularization support particularly powerful? Definitely not. With an automated script to generate a ton load of mappings it could approach the capability of KDE's tool, albeit with no range specific filtering available. But its specific purpose is a different use case: live two-way mapping. And for that you necessarily have to restrict the flexibility of output, because they have to map in reverse. > We didn't choose svn2git at random: we started using it because KDE (a > much bigger project than Boost) used it to solve the exact same problems > Boost has to solve: modularization + Git migration. Svn2git is a completely different tool to git2svn. Svn2git is a much superior tool, albeit rather harder to configure (correctly). > You'd have to have some pretty compelling arguments, a complete plan for > migration and modularization, and be prepared to lead the effort > yourself for me to throw out years of planning and coding to use a > different tool. Do you really think you're making a reasonable > suggestion? I'm sorry you have read my confusion that way Dave. I would have hoped that after all the years we have known one another you wouldn't have interpreted my comments in that way. Just to be clear and for the record, I have no compelling arguments, no plan for migration, and I am in no way criticizing your work, your leadership, nor suggesting the throwing away of any planning or coding. I apologise unreservedly if anything in my words appeared that way. I am absolutely sure that you have given this the very deepest of thought and I - as always actually - trust your judgment. I am simply confused. > > I think it would be quite easy to set up a live perfect Git mirror of all > > Boost SVN, > > "Perfect," really? I think you are grossly underestimating some of the > strange ways that the SVN filesystem has been used over Boost's history. > >From http://subgit.com/book/index.html#branches-mapping it's clear that > the SubGit tool isn't equipped to deal with them properly. For example, > there's no revision range limiting in the branch mapping, a feature of > svn2git that we actually *need* to use. Perfect for me means that HEAD and releases work perfectly. I personally feel little priority about perfect preservation of history. > > do a transition period where SVN is writeable but GIT read only, and > > then one day the switch is flipped and it goes the other way > > round. That way anyone dependent on SVN keeps on working, but without > > write access. > > Again, I think a two-way mirror could be a really nice addition to the > existing transition plan, if someone is willing to put in the elbow > grease to set it up. Are you volunteering? We can talk about this at C++ Now next week, but if we were to coordinate our efforts and I have definite approval and support from Boost SC, I have no objection to volunteering for this. There is also the matter that SubGit would probably need some money paid for it as a matter of good faith. I would emphasize that a successful two way mirror does impose substantial restrictions on the variety of modularization possible so long as the mirror is active. That probably is unacceptable to you given your apparent plans. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

2 1

Re: [boost] Git Modularization Ready for Review
by Niall Douglas 11 May '13

11 May '13

> Niall Douglas <ndouglas(a)blackberry.com> writes: > > > Me personally I'd just chuck away any unmappable historical information. > > Chalk it up to a cost of transition. If they really need the history, > > they can go fetch it from the read-only SVN repo. > > I see you've not been keeping up with the list lately ;) Daniel et. al. > suggested doing just that a few months ago and was met with such a chorus of > criticism, they didn't really have a choice but to fix it. Never actually was on this list, not ever, until recently as it's a lot of extra reading. Been involved with Boost for over a decade though. > Personally, I agree with the chorus. After all, the point of a VCS is to have a > history of the code's evolution to a point. The VCS, be it SVN, Git, whatever, is > just a means to get that history. Jetissoning the ends for the means seems > misguided. No, it's a cost of doing an upgrade. Those of you who ever migrated a large CVS to SVN transition know what I mean: stuff gets lost, and actually it isn't important enough to preserve that it requires a quadrupling of transition effort when a read-only copy of the old technology repo is good enough. Distributed SCM is much more dimorphic again, and you *have* to accept some data loss. Let me put this another way: those who want no history loss ought to be the ones volunteering the additional time to preserve history. What actually happens sadly is then the argument becomes we must stick with whatever the old technology is, because people will choose a small reduction of productivity every day over fixing tooling once and for all ("programmers program, they don't do tooling"). I *still* find CVS in use in places because "history must never ever be lost", and given the anti-productivity nature of CVS that costs far more in present developer time than accepting a 5% or 10% history loss, most of which will never significantly matter anyway because it occurs on the edges where SCMs dimorph. > What happens in a few years time when Git is replaced with the next big thing? > Do we lose the history again? And then again when that gets replaced too? That's exactly what happens. Bitrot is always inevitable in the long run. Here call it "non-fatal bitrot" :) My only red line is corruption of past and present source code releases. It must *always* be possible to check out tag X and build release X. Other than that, I'm flexible, including loss of branch integrity, because in the end if that branch is really important its owner will manually fix up the damage. > > I fear that if modularization is taken to its logical extreme, you > > could see submodules get out of step with other submodules. You may of > > course have already anticipated this and have implemented something I > haven't realized. > > As I said, I am confused. > > Can you explain a bit more about what you mean by out-of-step? The whole > point of modularising the code is to *help* modules to get out-of-step and > therefore be easier to develop and test independent of what other Boost > libraries are doing. But perhaps you mean something else? Well, the Git way of helping stuff get out of step is that everyone gets their own full copy of the whole repo, and their copy is just as important as anyone else's copy. You clone, you develop and test, and optionally push changes elsewhere which could be your friend, your team, your employer, or of course some central authoritative copy. So I'm afraid I just don't get the present design for a library as small and as tightly integrated as Boost. Something huge and cleanly separated like KDE sure, but for Boost I suspect it's overkill. Unless Boost plans to grow 10x in the next three years that is. > > [1]: By findable I mean that when Boost library users do #include > > <boost/whatever> they get the main Boost repo version, not the > > submodule version. I absolutely would expect an automated tool to pull > > headers from submodules, check them for ABI breakage and push them > > into the main repo. My point is that some sanity check ought to be there. > > I'm not following why you would want to do this. Perhaps you can explain what > problem you are anticipating and how this would solve it? Most of Boost is implemented in headers, very much unlike KDE or most other C++ libraries. Moreover, those headers are quite brittle, unlike KDE or most other C++ libraries. If broken into submodules, I can see an apparently innocent change in submodule X appearing to compile and be okay in developer X's set of submodule clones, but silently be a breaking change with a simultaneous change in submodule Y by developer Y. Why this matters is because when in git you go to push, git will force you to merge before push and at that point you "see" the breakage by a conflict appearing (hopefully) and if not then your immediate next compile will fail. With the submodule approach that doesn't happen, so you *don't* see the breakage till much later when the regression tests suddenly start failing. I'm a great believer in refusing to let programmers commit code which breaks other code rather than nagging them later to fix an earlier commit. The point of failure notification ought to be as close to cause as possible. > I also don't get what 'findable' means. What would a non-findable header be? Any internal header only findable by internal implementation. What I'm basically suggesting is an approach where the master repo keeps a gold candidate set of headers automatically extracted regularly from the submodules. Then on push a hook can do appropriate black magic to force the pusher to merge headers before the push. Then stuff which is broken appears broken as soon as possible, rather than suddenly emerging many days later. Does this make sense? Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

3 2

Boost build broken on the trunk
by Edward Diener 11 May '13

11 May '13

After getting the latest Boost from the trunk, and after running bootstrap I try '.\b2 install --prefix=c:\programming\bin' and get: ---------------------------------------------------------------------- Performing configuration checks - 32-bit : yes - arm : no - mips1 : no - power : no - sparc : no - x86 : yes - has_icu builds : no warning: Graph library does not contain MPI-based parallel components. note: to enable them, add "using mpi ;" to your user-config.jam - zlib : no - iconv (libc) : no - iconv (separate) : no - icu : no - icu (lib64) : no - message-compiler : yes - gcc visibility : no - long double support : yes warning: skipping optional Message Passing Interface (MPI) library. note: to enable MPI support, add "using mpi ;" to user-config.jam. note: to suppress this message, pass "--without-mpi" to bjam. note: otherwise, you can safely ignore this message. warning: No python installation configured and autoconfiguration note: failed. See http://www.boost.org/libs/python/doc/building.html note: for configuration instructions or pass --without-python to note: suppress this message and silently skip all Boost.Python targets - zlib : no (cached) C:/Programming/VersionControl/boost/tools/build/v2/build\virtual-target.jam:1099 : in virtual-target.register-actual-name from module virtual-target error: Duplicate name of actual target: <pc:\programming\bin\lib>libboost_date_t ime-vc110-mt-gd-1_54.lib error: previous virtual target { common%common.copy-libboost_date_time-vc110-mt- gd-1_54.lib.STATIC_LIB { msvc%msvc.archive-libboost_date_time-vc110-mt-gd-1_54.l ib.STATIC_LIB { msvc%msvc.compile.c++-gregorian\greg_month.obj.OBJ { gregorian/g reg_month.cpp.CPP } } { msvc%msvc.compile.c++-gregorian\greg_weekday.obj.OBJ { g regorian/greg_weekday.cpp.CPP } } { msvc%msvc.compile.c++-gregorian\date_generat ors.obj.OBJ { gregorian/date_generators.cpp.CPP } } } } error: created from ./install-proper-lib-static error: another virtual target { common%common.copy-libboost_date_time-vc110-mt-g d-1_54.lib.STATIC_LIB { msvc%msvc.archive-libboost_date_time-vc110-mt-gd-1_54.li b.STATIC_LIB { msvc%msvc.compile.c++-gregorian\greg_month.obj.OBJ { gregorian/gr eg_month.cpp.CPP } } { msvc%msvc.compile.c++-gregorian\greg_weekday.obj.OBJ { gr egorian/greg_weekday.cpp.CPP } } { msvc%msvc.compile.c++-gregorian\date_generato rs.obj.OBJ { gregorian/date_generators.cpp.CPP } } } } error: created from ./install-proper-lib-static error: added properties: <log-api>winnt error: removed properties: <log-api>generic C:/Programming/VersionControl/boost/tools/build/v2/build\virtual-target.jam:484: in actualize-no-scanner from module object(file-target)@4017 C:/Programming/VersionControl/boost/tools/build/v2/build\virtual-target.jam:134: in class(a)virtual-target.actualize from module object(file-target)@4017 C:/Programming/VersionControl/boost/tools/build/v2\build-system.jam:720: in load from module build-system C:\Programming\VersionControl\boost\tools\build\v2/kernel\modules.jam:289: in im port from module modules C:\Programming\VersionControl\boost\tools\build\v2/kernel/bootstrap.jam:139: in boost-build from module C:\Programming\VersionControl\boost\boost-build.jam:17: in module scope from module ------------------------------------------------------------------------ This is on Windows but the same thing occurs on my Linux distros. Cannot this be fixed ? I posted the same message for Linux failure on the Boost Build mailing list but received no response.

3 4

[bootstrap/1.53] jam0.exe crashes when bootstrapping for VC2012 AMD64
by rjeczalik 11 May '13

11 May '13

Hi, I'm trying to build Boost 1.53 using VC2012 amd64 (toolset=msvc-11.0 address-model=64) and Windows Server 2012 Standard. Bootstrapping fails with jam0.exe crash - some crash info: Crash stacktrace: ntdll.dll!000007f9bc781069() KernelBase.dll!000007f9b978764e() KernelBase.dll!000007f9b97d3658() jam0.exe!_findnext64i32(__int64 hFile, _finddata64i32_t * pfd) Line 165 jam0.exe!file_dirscan(_object * dir, void (void *, _object *, int, __int64) * func, void * closure) Line 180 jam0.exe!builtin_glob(frame * frame, int flags) Line 718 jam0.exe!function_run(_function * function_, frame * frame, _stack * s) Line 3390 jam0.exe!evaluate_rule(_object * rulename, frame * frame) Line 264 jam0.exe!function_call_rule(_jam_function * function, frame * frame, _stack * s, int n_args, const char * unexpanded, _object * file, int line) Line 468 jam0.exe!function_run(_function * function_, frame * frame, _stack * s) Line 3950 jam0.exe!parse_file(_object * f, frame * frame) Line 57 jam0.exe!main(int argc, char * * argv, char * * arg_environ) Line 488 jam0.exe!__tmainCRTStartup() Line 241 jam0.exe!mainCRTStartup() Line 164 kernel32.dll!000007f9b9de167e() ntdll.dll!000007f9bc7a3501() Line where it crashed was: if (!FindNextFile((HANDLE)hFile, &wfd)) { I've tried to watch the values of arguments passes to FindNextFile() - hFile looked like proper handle, however wfd.cFileName and wfd.cAlternateFileName contained garbage. Is this a known issue for 1.53? I've compiled version 1.52 using the same environment and the same configuration and everything went ok, I did not manage to reproduce the crash. It looks like only version 1.53 is affected. Regards, Rafael Jeczalik

5 5

Re: [boost] [log] Patch: rotating file collector
by Andrey Semashev 10 May '13

10 May '13

On Tue, Apr 23, 2013 at 3:58 PM, Alexander Arhipenko <arhipjan(a)gmail.com>wrote: > > I've added implementation of rotating file collector - > the patch against boost log trunk attached. > This is not the final version, I'm going at least to finish most of the > TODOs. > > However, it would be nice to receive feedback and questions from > library author as well as from people interested in this feature. > > Andrey, could you please find several minutes to review the attached patch? > Thanks for the patch. I didn't look deeply into it yet but from the first glance it looks like you changed the existing file collector rather than introduce an alternative one. Am I right? If so, could this be made as a pure addition rather than modification? I would prefer to keep the current behavior also available for the users. Also, I would like to discuss following question with you : > rotate_file invocation in ~text_file_backend - > I would prefer to have this call during text_file_backend construction > phase. > I'll have to take a closer look later to answer that but it seems odd to have to rotate something when nothing have been written yet. The rotate_file call is intended to place the written file to the storage governed by the collector, and at construction this file hasn't been created yet. Could you describe why you need this?

3 7

[algorithm] More general purpose algorithms?
by Sai Kiran Talamudupula 10 May '13

10 May '13

Hi, I am new to using boost libraries. I want to contribute to [boost.algorithm]. I see that there is scope for adding more general purpose algorithms in the library now. If I might have some ideas, is this the right place to propose and discuss them? Do I need to follow any procedure and/or address a specific person? Best, Saki.

2 1

Wanted: reviewers for boost.test doc overhaul
by legalize+jeeves＠mail.xmission.com 10 May '13

10 May '13

[Please do not mail me a copy of your followup] As per the "What do we do about boost.test?" thread last year, the biggest complaint seemed to be the documentation. I'm overhauling the documentation using quickbook and I'd appreciate incremental feedback along the way. Any takers? -- "The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline> The Computer Graphics Museum <http://computergraphicsmuseum.org> The Terminals Wiki <http://terminals.classiccmp.org> Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

5 4

[TypeErasure] references
by Chapman, Alec 10 May '13

10 May '13

Hi Steven, I have a somewhat-generic type erasure class that I would like to switch to yours. The main difficulty I can see is in the way capturing by reference is handled. The approach I take in my class is to pass a boost::reference_wrapper to the constructor: typedef mpl::vector<copy_constructible<>, type_id_<>, incrementable<> > requirements; int i = 0; any<requirements> x(boost::ref(i)); // capture i by reference ++x; // i == 1 any<requirements> y(x); // makes a copy of i ++y; // i == 1, any_cast<int>(y) == 2 My motivation is that I have a bunch of template functions already written that I often call directly, but in other cases I need to compile them separately by instantiating them with any<...>: ---------------------- module 1 ------------------------- // some long algorithm that I don't want to modify to be aware of any<...> template<class T> void f(T& t) { ++t; T t2 = t; ++t2; // do something with t2 } // make a type-erased version for separate compilation void any_f(any<requirements>& x) { return f(x); } -------------------- module 2 ---------------------------- // provide a thin wrapper that applies type erasure before calling any_f template<class T> void f_fwd(T& t) { any<requirements> x(boost::ref(t)); any_f(x); } // some function that needs to call f void g(int& i) { // do something with i... // then pass it to f f_fwd(i); } Is something like this possible with your method? Are there advantages that I'm not seeing to having the type signature contain information about whether the object is held by reference? Thanks, Alec

3 6

Re: [boost] Git Modularization Ready for Review
by Niall Douglas 09 May '13

09 May '13

> > I'm far more confused as to why? Surely the conventional approach is to > > convert a SVN repo to GIT. > > Good luck with that, given the way SVN "branches" (really directories) > have been used in Boost's history. No automated tool is able to > determine how to map those things properly onto Git branches. You can > see evidence of that in repositories.txt (look at the "build" repository > declarations for example). Me personally I'd just chuck away any unmappable historical information. Chalk it up to a cost of transition. If they really need the history, they can go fetch it from the read-only SVN repo. > You act as though we haven't been thinking about how to do this well and > working on it for years already. We're quite well-aware how submodules > work. The use of submodules by most developers is supposed to be a > temporary transitional measure, since modularization is designed to > allow you to work with only the parts of Boost relevant to your project. You have mistaken my confusion for criticism. I am not criticizing. I am confused. > > Also, how is Boost going to manage dependency breakage across multiple > > submodules? > > What is "dependency breakage?" Generally speaking Git submodules are for loosely coupled relations because of how Git implements submodules. Some of Boost's constituent libraries do meet that definition (BPL, BGL, Math). Some do not, as they are too essential because so many other libraries depend on them (anything likely to enter the standard with TR2, the MPL, the PPL etc). I fear that if modularization is taken to its logical extreme, you could see submodules get out of step with other submodules. You may of course have already anticipated this and have implemented something I haven't realized. As I said, I am confused. > > Are you planning to keep headers in one monolithic repo > > No > > > but keep anything resulting in a DLL/SO in a submodule? Or are you > > planning to break out the headers into submodules too? > > Yes; it's already done, modulo some expected adjustments due to the > review I am requesting. One solution is to require all findable headers to live inside the main Boost repo [1], and only implementation to reside in submodules. That keeps minds focused on dependency management. [1]: By findable I mean that when Boost library users do #include <boost/whatever> they get the main Boost repo version, not the submodule version. I absolutely would expect an automated tool to pull headers from submodules, check them for ABI breakage and push them into the main repo. My point is that some sanity check ought to be there. > > I can see it becoming quite easy for submodules or branches or forks > > thereof to get out of step with one another. > > That's a *good* thing. We're trying to decouple. Most libraries will > be developed against the previous release of their dependencies. > > > I can see the present submodule heavy approach introducing a lot of > > anti-Git workflow because those submodules inside the boostorg > > organization are treated as special compared to other submodules. > > I don't have any idea what you mean here Git generally has you clone the authoritative master repo, you create a branch, make your changes. Once you're finished, you fetch latest master, merge into your branch until it's up to date, then generate a patch or pull request from your branch to authoritative master. Whoever gatekeeps that repo does the merge. Where I'm getting confused - again - is that it would seem that the submodule repos inside the Boost org section on github are the ones to be regression tested and used to assemble releases. So, instead of treating all git repos as one-among-many as say Linux would do, we've got a special "high" gold candidate set of git repos and then all other git repos. This appears to add an extra layer of syncing and merging, because surely Boost admin has the power to modify any of the high gc set of repos. I'm not saying that this choice isn't for very good reasons. It's just that from my experience a submodule heavy git repo with lots of tightly coupled submodules becomes a royal PITA for end users because you get all sorts of weird obtuse breakages for apparently no reason at the time. Maybe of course it's just me, and I have some mental block others don't have. And I absolutely agree that other projects such as KDE have adopted your approach and it seems to work for them. However Boost is not KDE. In my mental model of the world, Boost more resembles the Linux kernel in terms of interdependencies and size. KDE has a vastly more stable intra-module ABI and much more loosely coupled submodules. This interpretation may be a mistake of mine. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

2 1

Re: [boost] The file boost/detail/endian.hpp needs to be set up for your CPU type
by Niall Douglas 09 May '13

09 May '13

> > How does one write a proposal to the C++ committee? > > http://isocpp.org/std/submit-a-proposal > > > I'll do it. This is a > > problem that probably comes up a lot, people then figure out some > > clumsy workaround and then forget about it. These workarounds are > > just that, and they impact the bottom line as programmers try and > > figure out some way of figuring them out. > > > > This should be standard. No workaround required. > > Jonathan hit the nail on the head.The C++ standard is essentially an open source > software project staffed entirely by volunteers. There is no such thing as > something that "should be standard" - there are only things that someone has > written a proposal for, and then gone to the trouble of shepherding through the > standardization process. Also, allocate a minimum of at least one year to achieve a successful shepherding, and that's for an obvious, uncontroversial change. ISO standards has large barriers to entry and for good reason: only those with stamina and the ability to repeatedly rewrite proposals to correctly include feedback will succeed. I'm not saying don't do it, because if there's a problem it should be fixed. I am saying that most of the work in writing a proposal isn't in writing and submitting one as that part is straighforward, it's in the shepherding part as Beman points out. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

1 0

The file boost/detail/endian.hpp needs to be set up for your CPU type
by Adrian_H 09 May '13

09 May '13

I saw this error and was wondering, can the endianness of a compiler not be determined through templates instead of using <endian.h>? Using macros seems to be pretty old-school and if headers are not updated could be just flat out wrong. -- View this message in context: http://boost.2283326.n4.nabble.com/boost-The-file-boost-detail-endian-hpp-n… Sent from the Boost - Dev mailing list archive at Nabble.com.

7 14

Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 09 May '13

09 May '13

> IIUC, the question is related to Qt's API for integrating with Qt's event > dispatcher, which (IIUC again:p) is used by QApplication, QCoreApplication and > QThread. > > Apologies if I'm off target here. Correct. I think the gold standard is a thread pool implementation which seamlessly allows Boost.ASIO to be combined with Qt's event dispatcher all in the single implementation. In other words, the thread pool can cope with multiple simultaneous event dispatcher implementations. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

1 0

[log] Is it lock free ?
by adrien courdavault 09 May '13

09 May '13

Hi I'm really interested by the new Log library. I would like to know if there is a part of this API that could be wait free, not the << operator perhaps, but a specific function to log a message without having to worry about a malloc or lock called inside the library. I would like to use this from a time critical thread. thank you

3 5

[predef] Status and review results?
by Rene Rivera 09 May '13

09 May '13

Just a quick message to mention that I've finished all the review related changes to the Predef library. And done some of the future tasks on the library. In particular the addition of endianness definitions and the moving of MinGW as a platform instead of a compiler (and hence the addition of BOOST_PLAT category of macros. And the one question I have is.. When will the review results of the library be decided on? I ask for two reasons. One, the obvious, is just to know if it's accepted or not. And to know if it's not accepted and hence that I should spend time to recreate a "boost/detail/endian.hpp" header that implements the Predef logic for endian detection. Note the project move to Github earlier this year (in preparation for the Boost git move). You can find the project at < https://github.com/grafikrobot/boost-predef>, and browse the current documentation at <http://tinyurl.com/cqqhhev>. -- -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim - grafikrobot/yahoo

8 31

[chrono/date] Two axes for a date design: validity check and representation and an essence date class/factory
by Vicente J. Botet Escriba 09 May '13

09 May '13

Hi, I would like to discuss about some alternatives to take in account the following use case "Reset a date if it resulting date is valid and report if this succeeds" when we have two axes of variation on the date design. Let me add two parameters to the possible date class. * validity: unchecked/checked * representation: serial, ymd(calendar), iso_ordinal, iso_week... date<serial, unchecked> is an unchecked serial date. It corresponds +/- to the N3344 date suggestion. date<ymd, checked> is a checked ymd date. It corresponds +/- to the H.H 2011 date proposal. WARNING !!! I'm not saying that a template class is a good thing, it is just to state clearly the features of the date. N3344 suggest a date::set_if_valid_date function. date<serial, unchecked> ud=...; if (ud.set_if_valid_date(y,m,d)) { // xx } else { // yy } But if we want to do as for the date constructors we will need multiple overloads again for this function :(. As show on this ML serial+unchecked dates validation could have some surprises. We can get the same service building a ymd date that can provide a way to be validated. //------------- // Validity check done when is_valid() is called on ymd_date. date<serial, unchecked> dd=...; date<ymd, unchecked> yd(y,m,d); if (yd.is_valid()) { // CHECK dd = yd; // xx } else { // yy } Instead of using explicitly date<ymd,unchecked> we can use a make_essence() factory that returns some kind of tuple essence_date<year,month,day> that is not a date, but its essence. It contains everything needed to build a date. This essence should be implicitly convertible to any date. The make_essence_date() factory supports all the different orders of parameters. The operator/() expression would also create an essence date. // -------------- //No validity check is done. date<serial, unchecked> ud = make_essence(y,m,d); date<serial, unchecked> ud1 = m/d/y; This essence dates support date validity, that is provides a is_valid() function. // -------------- // Validity check done when is_valid() is called on essence. date<serial, unchecked> ud; auto d = y/m/d; if (d.is_valid()) { // CHECK ud = d; // xx } else { // yy } //-------------- // Validity check done at construction of cd. serial_date<checked> cd = make_essence(m,d,y); //serial_date<checked> cd = m/d/y; Summary: IMO Having checked and unchecked dates with several representations could help to make dates interface more precise and concise. Checked dates are always valid. Dates with a specific representations would provide only, as suggested by Howard, only the functions that are efficient. The use of essence dates factories simplify the interface of all the date classes construction. Only 1 constructor by representation needed independent of the parameters order date(essence<ymd> &&); date(essence<serial> &&); date(essence<iso_ordinal> &&); date(essence<iso_week> &&); Comments welcome, Vicente P.S.The essence date classes and the contextual dates are quite related. I prefer to let this 3rd contextual axe of variation out of the current scope. I will try to integrate it soon.

2 3

[trac] Add component for Boost.Log
by Andrey Semashev 09 May '13

09 May '13

Hi, Not sure whom to ask, but could someone create a component "log" for Boost.Log in Trac? I (andysem) am the maintainer. Thanks.

2 2

JSON parsing library project for GSoC
by Olexandr Popilovsky 09 May '13

09 May '13

Hi. My name is Olexandr Popilovsky and I'm a student of Taras Shevchenko National University of Kyiv. I made a proposal for JSON parsing library and I would like to know that can I be accepted for this project and if yes, what I should to do to increase my chances (demo or smt.). thanks. waiting for your answer =)

4 6

Company copyright release examples
by Brendon Costa 08 May '13

08 May '13

I am looking into asking the company I work at for an official written "release" on the copyright for work I with to contribute to boost as per the description at: http://www.boost.org/development/requirements.html I will be developing this in my own time outside of work hours but I will need this release due to clauses in my contract and the relationship that the proposed library would have to my normal work. Are there any examples of what this release should look like for boost to accept it? I think having a sample release available on the page I linked to above would be really useful. Thanks, Brendon.

4 6

[iterator] Silent-but-deadly bug in iterator_facade category
by Gabriel Redner 08 May '13

08 May '13

Hi folks, I've stumbled across a nasty problem with iterator_facade in which code which appears correct and compiles fine can cause runtime problems. Consider an iterator_facade which just wraps a random access iterator and applies a transformation to it: char transform(int i) { return 'a'; } struct my_iterator : public boost::iterator_facade<my_iterator, char, // value_type std::random_access_iterator_tag, // *** char> // reference { my_iterator(const std::vector<int>::iterator& it) : _it(it) {} char dereference() const { return transform(*_it); } bool equal(const my_iterator& other) const { return _it == other._it; } void increment() { ++_it; } void decrement() { --_it; } void advance(int n) { std::advance(_it, n); } int distance_to(const my_iterator& other) const { return other._it - _it; } private: std::vector<int>::iterator _it; }; Now if I have an STL-style function which is overloaded on the iterator category, clearly the random-access version will be selected. template <typename TIterator> void funcImpl(TIterator it, std::input_iterator_tag) { std::cerr << "Running func treating 'it' as input iterator\n"; } template <typename TIterator> void funcImpl(TIterator it, std::random_access_iterator_tag) { std::cerr << "Running func treating 'it' as random access iterator\n"; } template <typename TIterator> void func(TIterator it) { funcImpl(it, typename std::iterator_traits<TIterator>::iterator_category()); } In the line marked ***, the docs suggest I should use boost::random_access_traversal_tag instead of std::random_access_iterator_tag - but when I do, the program no longer selects the random access version of 'func', choosing the forward-only version instead! The iterator_category of my_iterator ends up as: boost::detail::iterator_category_with_traversal<std::input_iterator_tag, boost::random_access_traversal_tag> The reason I called this a 'deadly' bug is that std::advance is suddenly a deathtrap: std::advance(it, -1); This is fine and legal for random access iterators, but if the forward-only version gets called instead, the behavior is undefined (on my system, it loops endlessly). The compiler doesn't complain either way - the problem surfaces only at runtime. Does the problem lie with iterator_category_with_traversal? It looks like it's intended in this case to be convertible to either std::input_iterator_tag or std::random_access_iterator_tag, but clearly something is wrong with the latter conversion. Any ideas? Thanks, -Gabe

7 14

[gsoc 2013] draft proposal for chrono::date
by Anurag Kalia 07 May '13

07 May '13

Hi, I mistakenly sent this draft as a reply to personal email of Vicente. I am sorry! Here it is again, verbatim. One related question though. I still haven't got the hang of a Mailing List. Is there a software takes the pain away from it. For example, I use outlook.com and '>' get appended in front of only the start of paragraph making it wholly unreadable. Thanks, Anurag Kalia. ---------------------------------------- > Date: Sat, 27 Apr 2013 18:14:09 +0200 > From: vicente.botet(a)wanadoo.fr > CC: anurag.kalia(a)outlook.com > Subject: Re: [boost] [gsoc 2013] draft proposal for chrono::date > > Le 27/04/13 16:58, Anurag Kalia a écrit : > >> I understand that you want to design your own library, I did the same, > >> but getting a coherent design would take you some time. > >> I suggest you to start with the H. Hinnant proposal as a reference and > >> state what you want to added, changed or removes. State clearly why do > >> you want these changes, what would be improved/solved. > >> > >> Don't forget to inspect the threads/discussion related to the H.Hinnant > >> proposal, and the paper N3344 Toward a Standard C++ 'Date' Class > >> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3344.pdf > > Hi Vicente, > > > > Thanks a lot for the exhaustive reply! I will get back to you after going through all the things you pointed out and also the paper you forwarded. But I have one quick question for now, from where can I start my search for the threads and discussions around this date proposal? > > > > > > > Hi, > > There were some interesting exchanges in > https://groups.google.com/forum/?fromgroups=#!forum/kona-date-lib > > I guess that if you request to the administrator s/he will be able to > give you read access to the existing threads (there are not too much). > > Best, > Vicente > I have finally implemented some representative functions in date class and calendar to get a better idea of the proposal. I have dropped the JDN storage for another implementation that I thought of in the middle of the night. I think it is a hybrid approach between serial and field-based implementations. Off the top of my head, without any alternative implementations at hand and benchmarks too, I can't think of something inherently wrong in it. I would really like to hear its gotchas, if any. I have overhauled my proposal on the basis of it. It doesn't contain other headings like about me etc for today. I have tried to incorporate all the previous points you noted before and have also tried to keep naming consistent. I did use uppercase constants in there but they are meant to be private. Is that okay? I knew little about the benchmarks before you sent me that paper. From what I got, they just iterate over a significant period of time and note the start and ending time. Is it more than that? And should I make them before or after I have multiple implementations in hand. I could get hold of your and Howard Hinnant's implementations for them, but then the APIs would have to line up, wouldn't they? Hope you find my proposal better this time around. With an open ear, Anurag Kalia.

9 95

[GitHelp] bootstrap.bat calls missing build.bat
by legalize+jeeves＠mail.xmission.com 07 May '13

07 May '13

[Please do not mail me a copy of your followup] OK, so I am experimenting with modular boost, following the instructions here: <https://svn.boost.org/trac/boost/wiki/TryModBoost> I cloned and did the submodule update. I didn't have CMake; is this why I experience a problem? What exactly does 'cmake -P forward_header.cmake' do? When I run boostrap.bat it fails early with an attempt to call build.bat which doesn't exist. Thanks for your time. -- "The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline> The Computer Graphics Museum <http://computergraphicsmuseum.org> The Terminals Wiki <http://terminals.classiccmp.org> Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

3 5

[quickbook][random] Build under doc/ broken?
by John Maddock 07 May '13

07 May '13

I'm not sure if this is a random or quickbook issue, but building the doc build under doc/ fails with current quickbook trunk. Any ideas? Thanks, John.

2 1

[wave] trace doesn't output errors.
by Adrian_H 07 May '13

07 May '13

I've got a really annoying and difficult to track down PP error. I'm attempting to use wave to see the expansion, but it is slow going. The output is correct, in both the g++ PP and the wave parser. g++ states: *error: macro "BOOST_PP_SEQ_ELEM_III" requires 2 arguments, but only 1 given*, wave states *warning: too few macro arguments: BOOST_PP_SEQ_ELEM_III*, but when I try using the tracer it doesn't say when this occurs. Is it possible to turn this on? Or is there no 'on' and I have to go into the wave code and code it on? If the latter, where would I do this? Thanks, Adrian -- View this message in context: http://boost.2283326.n4.nabble.com/boost-wave-trace-doesn-t-output-errors-t… Sent from the Boost - Dev mailing list archive at Nabble.com.

3 7

Git Modularization Ready for Review
by Niall Douglas 07 May '13

07 May '13

> After substantial work, including massive changes by me and Daniel Pfeifer to > KDE's svn->Git conversion tool, we have captured every Boost SVN commit in a > Git repository. You can view the results at > > http://github.com/boostorg > http://bitbucket.org/boostorg > > Daniel and I are ready to accept your feedback on the results of modularization, > and especially your pull requests containing edits to the ruleset. I will the > steering committee to establish a formal review period, though. I'm a bit confused. This looks like a hand written map of parts of Boost SVN onto multiple GIT repos. Am I understanding correctly? I'm far more confused as to why? Surely the conventional approach is to convert a SVN repo to GIT. Then people hive off their particular bits into submodules as and when they themselves decide and they are ready. It looks here that Boost has decided on skipping the intermediate stage and going straight to submodules. That sounds awfully fraught: it also demands a lot from those library maintainers not familiar with Git. Submodules are extremely different to SVN externals - they're a very light link, and in many occasions Git does not auto-update submodules even when you tell it (i.e. it'll fetch, but silently not checkout head if it thinks you might lose data). Also, how is Boost going to manage dependency breakage across multiple submodules? Are you planning to keep headers in one monolithic repo but keep anything resulting in a DLL/SO in a submodule? Or are you planning to break out the headers into submodules too? I can see it becoming quite easy for submodules or branches or forks thereof to get out of step with one another. I can see the present submodule heavy approach introducing a lot of anti-Git workflow because those submodules inside the boostorg organization are treated as special compared to other submodules. I'm confused. Sorry. I'm probably not making any sense. Is there a design rationale document somewhere? I can't see one up to date on Google. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

3 2

Re: [boost] Live read-only GIT mirrors of Boost trunk SVN
by Niall Douglas 07 May '13

07 May '13

> > All branches and tags, as far as I can tell, are mirrored correctly. I've > > set a cron job every 24 hours. Theoretically if we had an authors mapping > > file it would work in the opposite direction too i.e. be read-write. > > Nice. You can find a complete author mapping here: > https://github.com/ryppl/Boost2Git/blob/master/authors.txt Arse. I only rebuilt the mirror this weekend because it wasn't mirroring tags/release/* which has obvious value. Fixed now. > > My next task is to live mirror a github repo into Boost Sandbox. Currently > > SubGit segfaults on this due to the complex SVN properties auto-translation > > which requires a specially marked up .gitattributes, but the author is very > > keen to fix the problem. In theory then it ought to just work. > > > > Any mistakes in my Boost mirror, or any problems, or even thoughts are > > gratefully received. > > Don't put too much effort into this; Boost SVN->Git modularization is > just about ready for review :-) My experience with SubGit has been very, very good. I would *strongly* recommend it over git2svn. The company which develops it has been very impressive in response rate and going the extra mile to help me figure out problems. BTW Dave with much help from the same company I've figured out the opposite flow: automated Git => Boost SVN. It took a lot of trial and error to work around Boost's MIME type and EOL conventions, but you can see an exact automated mirror of https://github.com/ned14/TripleGit at http://svn.boost.org/svn/boost/sandbox/triplegit/. I had to squash history because of the MIME type problems though :( but from now on it should be live. I think it would be quite easy to set up a live perfect Git mirror of all Boost SVN, do a transition period where SVN is writeable but GIT read only, and then one day the switch is flipped and it goes the other way round. That way anyone dependent on SVN keeps on working, but without write access. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

3 2

[chrono/date] Unit specifiers arithmetic
by Vicente J. Botet Escriba 07 May '13

07 May '13

Hi, Moving from checked dates to unchecked ones by default and forcing to user the Unit specifiers year/month/day in any date constructor (even the unchecked ones) has some ugly consequences. Note that I was able to build an unchecked date as date d(2013,5,6, no_check); Given year y; month m; day d; the following will not compile now as the constructors expects a year but y+1 is an int. date d(y+1, m, d); The user needs to type date d(year(y+1), m, d); Is this what we want to provide to the user or should we add basic arithmetic on these unit specifiers? Best, Vicente

4 7

Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 07 May '13

07 May '13

> Le 30/04/13 17:16, Niall Douglas a ?crit : > >> Le 29/04/13 21:35, Niall Douglas a ?crit : > >> Could you explain me what a central asynchronous dispatcher is? > > An asynchronous procedure call implementation. Here's Microsoft's: > > http://msdn.microsoft.com/en- > us/library/windows/desktop/ms681951(v=vs.85).as > > px. Here's QNX's: > http://www.qnx.com/developers/articles/article_870_1.html. > > Boost.ASIO is the same thing for Boost and C++ but implemented by > > application code. It is *not* like asynchronous POSIX signals which are a > > nearly useless subset of APCs. > I don't see the term "central asynchronous dispatcher" used in any of > the links. Could you clarify what it is? I have to admit I'm struggling to see where your block is, but Dave Abrahams often found the same with me, so it must be me. A central asynchronous dispatcher is the loop which sends callbacks/events to be invoked/processed by other execution contexts. Every OS has at least one in the kernel. Most GUI toolkits like Qt have one. Boost has at least one in the form of Boost.ASIO. The central means one execution context does the dispatch. The asynchronous means that callbacks are processed by recipients asynchronous to the dispatcher. And dispatcher, well that dispatches. > >> If not, please could you elaborate what kind of optimizations can be > >> obtained? > > If you have transactional memory in particular, you gain multi-CAS and the > > ability to (un)lock large ranges of CAS locks atomically, and a central > > dispatcher design can create batch lists of threading primitive operations > > and execute the batch at once as a transaction. Without TM, you really need > > the kernel to provide a batch syscall for threading primitives to see large > > performance gains. > I'm really lost. Multi-word Compare-And-Swap (MCAS) is one of the biggest gains from Transactional Memory. Indeed WG21 has SG5 dedicated to integrating TM into C++17. Some models of Intel's Haswell come with hardware TM assist. I'd take a reasonable guess that MCAS will benefit centralized kernel-based threading primitives architectures such as Windows NT more than decentralized threading primitive architectures such as POSIX. That said, I could see Linux using TM for batch multi-kernel-futex ops, though I'd have to say implementing that without breakage would be daunting. Either way, a central asynchronous dispatcher has information a decentralized implementation does not. That opens more scope for optimization. > > Boost.ASIO's core is boost::asio::io_service. That is its dispatcher > > implementation which each dispatch execution context being executed via > > boost::asio::io_service::run() which is effectively an event loop. Third > > parties then enqueue items to be dispatched using > > boost::asio::io_service::post(). You don't have to run Boost.ASIO using > > multiple threads: it can be single threaded. > > I could not comment until I understand what Boost.ASIO provides and it > can interact with thread_pools :( Boost.ASIO provides a per-thread capable event loop implementation. That automatically makes it an example of a thread pool manager. You may find N3562 Executors and schedulers coproposed March 2013 for Bristol by Google and Microsoft of use to you in understanding the relation between thread pools and Boost.ASIO (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3562.pdf) My proposed Boost.AFIO library is an implementation of that same N3562 idea, albeit I extend Boost.ASIO which is IMHO more C++-y whereas Google and Microsoft have gone with proprietary implementations. Also, they include timing and many other more general purpose features, and mine does not (currently) as it's mainly aimed at maximising input/ouput with highly jittery random latency storage. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

5 13

[heap] van Emde Boas tree
by Jeremy Murphy 07 May '13

07 May '13

Should I contact Tim Blechmann directly about the idea of adding a van Emde Boas tree to Boost.Heap, or is proposing it here the appropriate way to go about it? Thanks, cheers. Jeremy

2 1

[any] Divergence between Boost.Any and standard library proposal
by Beman Dawes 07 May '13

07 May '13

A fresh draft of the proposal is up at http://beman.github.com/dot16/any-proposal.html In testing new any_cast examples, Boost.Any is handling one case differently from the proposal: any x; ... x = "Meow"; // x holds const char* This works fine with the Adobe implementation, but with the Boost implementation g++ 4.7.0 -std=c++11 reports: In file included from any_cast_test.cpp:5:0: c:\boost\trunk/boost/any.hpp: In instantiation of 'boost::any::holder<ValueType>::holder(c onst ValueType&) [with ValueType = char [5]]': c:\boost\trunk/boost/any.hpp:52:49: required from 'boost::any::any(const ValueType&) [wi th ValueType = char [5]]' c:\boost\trunk/boost/any.hpp:124:13: required from 'boost::any& boost::any::operator=(Va lueType&&) [with ValueType = const char (&)[5]; boost::any = boost::any]' any_cast_test.cpp:79:7: required from here c:\boost\trunk/boost/any.hpp:169:27: error: array used as initializer VC++ 2012 gets the same error, albeit with a much longer set of messages. AFAICS, the Adobe (and the proposed standard) behavior is preferred. The type does need to decay. Comments? --Beman

6 10

[chrono/date] date conversion and arithmetic with unvalidated dates
by Vicente J. Botet Escriba 07 May '13

07 May '13

Hi, Note that N3344 suggest only day arithmetic for a day representation (which is always valid) and suggest only only a date representation. Could we apply arithmetic operations on a unvalidated date (without striving on UB)? e.g. day arithmetic on a ymd_date ymd_date d1(year(2013), may, day(66)); ymd_date d2 = d1 + day(1); If defined, which must be the value of d2? Could we convert a date representation to another one if the source date is unvalidated (without striving on UB)? e.g. ymd_date -> days_date ymd_date d1(year(2013), may, day(66)); days_date d2 = d1; If defined, which must be the value of d2? Best, Vicente

4 5

[chrono/date] validated versus valid dates
by Vicente J. Botet Escriba 07 May '13

07 May '13

Hi, Allowing to build dates that are not validated doesn't mean that they are not valid. A validated date is always valid. E.g date d(year(2013), may, day(5)); d is not a validated date but is valid. Having a is_validated() function in addition to is_valid() could have its uses assert( ! d.is_validated() && d.is_valid() ); is_validated() function forces to use a bit to store this information on the date representation, but it improves the performances of the is_valid() function. Moving from a possible unvalidated to a validated one would need date d1; ... date d2(d1.year(), d1.month(), d1.day(), check); Instead of this a validate factory makes this clearer date d1; ... date d2 = validate(d1); date validate(date const& dt) { if (dt.is_validated()) return *this; else if (dt.is_valid()) { date res(dt); res.set_validated_(); // this is private return res; } throw bad_date(); } Best, Vicente

2 3

Am I missing something or is Boost: String dictionary?
by david.hagood＠gmail.com 06 May '13

06 May '13

One of the libraries I work with (libXML2) has a very useful concept called a string dictionary, and I am surprised this doesn't appear to be in either STL or Boost. Am I missing something, or is Boost missing something? The basic idea is: Given you have a string and an instance of a dictionary, you can: 1) check if the string is already in the dictionary. 2) Add the string to the dictionary and return the dictionary entry (if the string is already present, return existing entry). The dictionary entries contain a copy of the string. Entries may be compared for equality/inequality in O(1) time. The lifespan of the strings in the entry is managed by the entry. This really simplifies writing parsers and the like, and is such a useful concept that I'm really surprised not to see it in STL or Boost.

6 6

[GitHelp]github.com/boostorg/sandbox comment confusing
by Larry Evans 06 May '13

06 May '13

At: https://github.com/boostorg/sandbox there's a comment by Beman from 10 yrs ago saying: Removed as obsolete - use Boost.Random instead which makes no sense to me. Also, are any of the sandbox files from svn going to be moved to this github sandbox? TIA. -regards, Larry

3 4

Fwd: GSOC:2013 Multiprecision Proposal Review
by Siddharth Jain 06 May '13

06 May '13

Please have a look at my proposal. The link to my proposal is http://www.google-melange.com/gsoc/proposal/review/google/gsoc2013/siddhart… and I have worked a lot on this proposal. Please suggest any changes which could be incorporated to improve this project. Regards Siddharth Jain

1 0

Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 06 May '13

06 May '13

> Le 02/05/13 18:01, Niall Douglas a ?crit : > >> That's orthogonal. Boost.Asio provides the funding blocks. A nicer > >> interface that doesn't require an explicit continuation passing style > >> transformation can be built with Boost.Context or a similar library. > >> But it probably needs a future implementation that integrates with > >> ASIO, which is one of the point of Niall Douglas. > > Spot on. Especially as parts of ASIO are due to enter with TR2. I worry that > > a thread pool designed without ASIO in mind would become an orphan isolate. > What a ThreadPool must provide to satisfy the ASIO requirements? That's a very good question. And for me to answer in specifics I'd need to think deeply about the issue, and study examples, neither of which time currently allows given C++Now is just around the corner. All I can say right now - and I agree this isn't very helpful - is make it compatible with opaque third party event loop dispatchers such as Qt's QCoreApplication and QRunnable. Because Qt's implementation details iare opaque to external code, if you can meet compatibility with that you'll probably be compatible with anything Boost.ASIO can come up with, especially as most of Boost.ASIO is header defined. I appreciate that isn't very helpful. Thread pool design is hard :( Niall

4 5

[config/multiprecision/units/general] Do we have a policy for user-defined-literals?
by John Maddock 06 May '13

06 May '13

Folks, I've been experimenting with the new C++11 feature "user-defined-literals", and they're pretty impressive ;-) So far I've been able to write code such as: auto i = 0x1234567890abcdef1234567890abcdef_cppi; and generate value i as a signed 128-bit integer. It's particulary remarkable because: * It actually works ;-) * The value is generated as a constexpr - all evaluation and initialization of the multiprecision integer is done at compile time. * The actual meta-code is remarkably short and concise once you've figured out how on earth to get started! Note however my code is limited to hexadecimal constants, because it can't do compile time radix conversion - that would require a huge meta-program for each constant :-( This is obviously useful to the multiprecision library, and I'm sure for Units as well, but that leaves a couple of questions: 1) We have no config macro for this new feature (I've only tested with GCC, and suspect Clang is the only other compiler with support at present). What should it be called? Would everyone be happy with BOOST_NO_CXX11_USER_DEFINED_LITERALS ? 2) How should libraries handle these user defined suffixes? The essencial problem is that they have to be in current scope at point of use, you can never explicitly qualify them. So I suggest we use: namespace boost{ namespace mylib{ namespace literals{ mytype operator "" _mysuffix(args...); }}} Then users can import the whole namespace easily into current scope right at point of use: int main() { using namespace boost::mylib::literals; boost::mylib::mytype t = 1234_mysuffix; } 3) How should the suffixes be named? There is an obvious possibility for clashes here - for example the units lib would probably want to use _s for seconds, but no doubt other users might use it for strings and such like. We could insist that all such names added to a boost lib are suitably mangled, so "_bu_s" for boost.units.seconds, but I'm not convinced by that. Seems to make the feature much less useful? Many thanks in advance for your thoughts, John.

6 12

[chrono/date] Performance goals and design summary
by Vicente J. Botet Escriba 05 May '13

05 May '13

Hi, After the discussion on other threads I would like to summarize some of my performances goals while refactoring the H.H chrono/date library, just to see if I was wrong and going on the bad direction: 1. *Be able to build dates without validating them.* 2. *I wanted the library to be as efficient as possible when the user uses constant objects or literals, no need to validate at runtime what has already been validated by the compiler*. 3. *Possibility to reassign a date if the parameters represent a valid date.* 4. *No a single date class is better than the others on all the algorithms*. 5. *No additional meta-data in absolute dates so that you don't pay for the relative dates overhead when using absolute dates.* 6. *The user must be able to get all the date related informations at once.* Do you have other? The way I have managed with these goals is 1. *P*rovide an unchecked date construction interface with a no_check_t parameter and an is_valid() function. 2. *T*he date parts day/month/year need to be validated or constructed with no_check_t. 3. dt.set_if_valid(year, month, day) 4. Define the Date requirements all the dates must satisfy, implement ymd_date, days_date, ... 5. Separate the absolute and the relative Date requirements into two Date concepts AbsoluteDate and RelativeDate. Provide at least a relative_date class based on the ymd representation. 6. Conversion between different concrete date classe. H.H approach respond to these goals in a different way 1. date and its parts provide constructors that are not validated, the validation is provided by factories as operator/. 2. I don't think this can be achieved when the date must be validated. 3. No problem, this could be added to H.H approach (at least for its YMD date). 4. Same approach. H.H proposes two classes chrono::day_point (only unchecked) and YMD date. 5. I'm not sure the date YMD class doesn't include meta data (Howard could you clarify your point here) 6. same approach. I have some questions for followed by my personal answer; * *Do you see some unnecessary goals, in particular, is the goal 2**necessary?* IMO, yes. Not providing an interface that allows compiler optimizations is against the C++ philosophy. The question is as always, what would be the gain? In the best case we could avoid 6 comparisons. * *Does the introduction of no_check to achieve goal 1 and 2 results in a uglier date interface?* IMO, yes, but I don't know how to achieve goal 2 without. * *Should a concrete date class provide just the functionalities it is able to do efficiently?* IMO, yes. This would prevent the user of non efficient services (Note that my current design doesn't follows this) * *Do we need a Date concept that a concrete date must model**?* IMO, yes. SO we need two levels, level one provides the most efficient service, level two provides an homogeneous interface. * *Do we need to make the separation between absolute and relative dates?* IMO, yes. While relative dates are powerful they incur on unwanted overhead when absolute dates are needed. Best, Vicente

4 14

[build] Conditional sources and compiler options
by Andrey Semashev 05 May '13

05 May '13

Hi, I'm trying to add some SIMD support to my library and I'm having problems with setting up my Jamfile properly. Basically, I have a number of source files that only need to be compiled when the compiler is of a specific version or later (say, gcc >= 4.7 or msvc >= 12 or intel >= X.Y on x86 but not for other compilers/architectures and not for older versions of the mentioned compilers). Next, I need to add special compiler options (specific for each compiler) just for these files. Natuarlly, I also have other source files that need not these tricks and should be compiled normally, without any special options. All source files have to be compiled into a single library (static or dynamic). Is there any way to do it in Boost.Build? I've read about alternatives in the docs, but they require duplicating the library target, which I'd like to avoid. I also read about conditional requirements, but as I understand they don't allow to specify version conditions (like <toolset>gcc >= 4.7). Also I didn't find any way to specify special build options for particular files. Thanks in advance.

2 2

[boost.preprocessor.iteration] relative file iteration not supported
by Adrian H 05 May '13

05 May '13

Hello, I have used Boost in the past and do like the use of the preprocessor as a way of making repetitious code. However, I found that in a project that I was working on, I needed the ability to iterate over a file relative to the file I was iterating from, and that file wasn't relative to any of the include directories. I thought about this and it makes sense to why it didn't work, but I can see that it can prove to be inconvenient sometimes when someone wishes to make library header files relative to each other to allow for flexible positioning of the related files in the source tree or not have to add new items to the include directory set. I have written a preprocessor library to fill this need, but was wondering if such a library would be of interest to the Boost community. I deliberately tweaked it to be similar to the Boost Preprocessor Iterator library, and can be acquired at https://sourceforge.net/projects/relativeiterate/, including documentation and an example located in the README.txt file. I would appreciate any feedback you may have on this and would be more than willing to make changes to accommodate what would be needed for it to be included into the Boost set. Thank you for your time. Adrian -- ======================================== Adrian Hawryluk BSc. Computer Science ---------------------------------------- Specialising in: OOD Methodologies in UML OOP Methodologies in C, C++ and more RT Embedded Programming GUI Development ========================================

3 4

[chrono/date] constructor, factories and validation
by Vicente J. Botet Escriba 05 May '13

05 May '13

Hi all, Two approaches to checking date validation have been proposed Howard approach: * date constructors build unchecked dates (provide the same order of parameters that the date factories. * date factories (expression using operator/()) build checked dates. * could be completed with make_date that will build checked dates. Advantages: * avoids the ugly no_check (that could be replaced by no_throw) Drawbacks * The 3 sets of date constructor factories must provide all the same order of parameters. * Creating a new factory will mean creating a new constructor on each concrete date class. * The factories must be friend of the concrete dates. My original approach complemented with make_date factory: * constructors without no_check build checked dates, and with no_check parameter build well unchecked ones. Provides only decreasing lexicographic order of arguments e.g. date(year,month,day), date(year,month,day,no_check_t). * make_date provides the usual combinations as provided by factory using operator/() and no_check. * date factories (expression using operator/()) build checked dates Advantages: * There are less date constructors. * We can add as many factories as we are able to construct with checking or not. Drawbacks * the no_throw/no_check/unchecked parameter is ugly and a source of conflict. Alternative approach (reverse the defaults): * constructors without check build unchecked dates, and with check parameter build well checked ones. Provides only decreasing lexicographic order of arguments e.g. date(year,month,day), date(year,month,day,check_t). * make_date provides the usual combinations as provided by factory using operator/() and check. * a make_checked_date could have also a sens. * date factories (expression using operator/()) build checked dates Best, Vicente

1 0

[operators] The Dangling Reference Polarization
by Daniel Frey 05 May '13

05 May '13

I see some good discussion going on, thanks to everyone participating! Rest assured that I value both side's contributions, it is important for me (and those agreeing with my perspective) to be able to defend this position and also to keep looking for improvements. If our side can not be defended, it's probably not good enough :) That said, here's what I hope can serve as a first summary, let's first look at it from a technical perspective: If an operator returns an rvalue reference (T&&), it is safe for all use-cases except binding the result to an rvalue- or const-lvalue-reference: T r = a + b + c; // no problem const T r = a + b + c; // no problem T& r = a + b + c; // compile-time error const T& r = a + b + c; // problem (P1) T&& r = a + b + c; // problem (P2) It seems that this is consistent behavior across at least GCC, Clang and VC++. If a compiler shows a different behavior, its likely a compiler-bug. Technically, there is no doubt that the above is a bug, but that doesn't answer the question of whether this is a bug of the user who wrote the above code or if it's a bug of the operator to return an rvalue reference instead of an rvalue. This is where we leave the technical-aspects-land and enter the minefield of opinions, expectations and decisions. I am of the opinion that the above problematic use-cases are a bug on the users side, my line-of-thoughts and my arguments are: a) The above code is explicit, you can spot it in the users code. It's not something that happens silently. b) The above code always looked suspicious to me anyways, it has a code-smell that I just don't like. c) It rely's on the fact that it extends the lifetime of a returned temporary value. The rules of the C++ standard that allow this are quite clear, and hence it's the users responsibility to make sure that there actually is a temporary value whose lifetime can be extended. It has always been an error if the expression returned a reference and not a value. Consider const std::string& oops = std::vector<std::string>(1, "hello, world" ).front(); This compiles are creates a dangling reference, as the standard says that front() returns a reference and not a value. It's not 100% comparable as in this case the standard guarantees a bug, but the main point for C++ has always been which guarantees are given and not about a certain expectation one might have. As an example: static_assert( std::is_empty< std::tuple<> >::value, "Expectation 1 broken" ); static_assert( std::is_empty< std::array< T, 0 > >::value, "Expectation 2 broken" ); // with any valid T The first case is certainly a reasonable expectation and it currently works for all implementations of std::tuple that I know of, but it is not guaranteed! If your code relies on it and it breaks in the future, you can not blame the person who modified std::tuple. The second case is also a reasonable expectation, but it breaks everywhere and AFAIK there is no standard-conforming way to implement std::array so that std::array<T,0> is empty. For the curious, here's the StackOverflow question I asked about it: <http://stackoverflow.com/q/15512827/2073257>. Another example about how to properly handle expectations vs. guarantees: <http://stackoverflow.com/q/14882588/2073257>. d) I fail to see any valid use-case for binding the result of the expression to a reference. Can someone please provide a convincing example of why (P1) or (P2) are needed/useful? Keep in mind that in the context of operator+ (or any other operator in question), we already require that the type T is copy-/moveable and that copy-elision most likely takes place if you use "T r = …" instead of "const T& r = …". e) The alternative needs to prove its claimed/theoretical efficiency in practice. Too often I have heard about "sufficiently smart compilers", but I'm more the prove-it-in-the-real-world type. So summarizing it once again: For a) and b), this is just an observation and my personal opinion. c) means it's important to talk about guarantees, not just about expectations (no matter how reasonable they are). d) poses the question if we loose something if we don't guarantee that (P1) and (P2) are allowed. I currently have several ideas/option of how we could improve Boost.Operators, some of which I already mentioned, some which only recently occurred to me. Before I will discuss these, I'd like to resolve (if possible) the Dangling Reference Polarization and gather more opinions/feedback. So far, I found the discussion both challenging and very helpful, again thanks to everyone participating! Best regards, Daniel

5 13

[gsoc] Boost.Multiprecision Proposal
by Saurav 04 May '13

04 May '13

Hi, I have attached my proposal for the Boost.Multiprecision project. It has been provided in PDF format for better readability. Please have a look and give your feedback. Best regards, Saurav

3 4

[Boost.ThreadPool] GSOC 2013 Proposal
by Ian Forbes 04 May '13

04 May '13

Hi, I am submitting my Google Summer of Code proposal for review. My proposal is for the Boost.ThreadPool library. It will be based on work done here: https://svn.boost.org/trac/boost/wiki/SoC2013#Boost.ThreadThreadPool The current proposal can be found at: http://cs.mcgill.ca/~iforbe/gsoc2013.html The original proposal can be found here: http://www.google-melange.com/gsoc/proposal/review/google/gsoc2013/en4bz/1 , although it has broken HTML tags and is ill formatted. Thanks goes to Vicente J. Botet Escriba for pointing out that Boost does in fact has LockFree concurrent data structures. Please feel free to respond with any questions or criticism. I will try to respond to the best of my ability. Thanks, Ian Forbes

1 0

[chrono/date] year/day/week literals
by Vicente J. Botet Escriba 04 May '13

04 May '13

Hi, on the GSoC discussion about Boost.Chrono/Date proposal we were discussing about date construction. Some of us think that we need to use named types for day, month, year and week so that the date constructors are not ambiguous. Everyone agree with the constant object for month. date dt(year(2013), may, day(3)); But having to use day(3) or year(2013) seems to wordy. I was wondering if we can not add some literals for day, year and week so that we can just write date dt(2013y, may, 3d); The advantage I see in addition to been less wordy, is that we will have a compile error when the year, day or week is out of range. What do you think? Vicente

5 11

Live read-only GIT mirrors of Boost trunk SVN
by Niall Douglas 04 May '13

04 May '13

The live GIT mirrors of Boost trunk SVN have become a bit stale in recent months: https://github.com/ryppl/boost-svn, long time favourite of many, now 4 months stale. https://github.com/Beman/boost-trunk-git-svn is now 2 months stale. https://github.com/alexanderkjeldaas/boost-mirror is fresh, but has no branches nor tags. They all generally use git-svn, which tends to be brittle and not translate commits perfectly unfortunately e.g. SVN eol properties and other such metadata. So I decided to try out a new Subversion <=> Git mirroring tool, SubGit v2.0 EAP (http://subgit.com/eap/) whose author very kindly gave me a free open source licence and the result is at: https://github.com/ned14/boost-trunk All branches and tags, as far as I can tell, are mirrored correctly. I've set a cron job every 24 hours. Theoretically if we had an authors mapping file it would work in the opposite direction too i.e. be read-write. My next task is to live mirror a github repo into Boost Sandbox. Currently SubGit segfaults on this due to the complex SVN properties auto-translation which requires a specially marked up .gitattributes, but the author is very keen to fix the problem. In theory then it ought to just work. Any mistakes in my Boost mirror, or any problems, or even thoughts are gratefully received. Niall

4 6

Specific-Width Floating-Point Typedefs
by Paul A. Bristow 04 May '13

04 May '13

There has recently been some discussion on improving portability of programs using floating-point. Drawing on the benefits from definition of typedefs for int32_t, int64_t, int128_t . we have drawn up a proposal to add similar typedefs for floating-point. Our draft document (in both html and pdf) is at https://svn.boost.org/svn/boost/sandbox/precision/libs/precision/doc/html/i… https://svn.boost.org/svn/boost/sandbox/precision/libs/precision/doc/precis… We hope to propose this to the SG6 Numerics subgroup of WG21 ISO C++ standards body. But would welcome comments from Boosters to help us improve this proposal. Thank you. Paul --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

8 17

date libary construction
by Shamsher Siddiqui 04 May '13

04 May '13

i am deeply regretting for not responding your Question and for not posting the google summer of code Proposal . my pre semester exams are going on so i was busy in preparing which is ending on 7 may which is coming tuesday so i will be always not active during this period but i will try to respond to discussion which happening on the mailing list . i am finally sending only the proposal part . Proposal for DATE LIBRARY 1)Construction of Date: According to paper [2] there were many benchmark set but date should be represented in both ways i.e field and serial .Field and serial representation have their advantage over each other under certain operation . No invalid dates can be entered considering range cheaking ,non existent date if entered bad_date exception is thrown during the time of constructing the date. Constructing constant object for day,week_day. Date construction concrete structure <template class date_concrete> class date_pre { //year, month,week day //constructors //basic accessors declaration //conversion accessors //airthematic operation //camparison operator for date camparison } 2) Arithematic Operation On date Date airthematic can be done on three units i.e day,month,year.In chrono date ::calendar(Gregorian calendar) length of month and year is not fixed : day arithematic Adding number of days to date until range doesn’t exceed Implementing last day arithmetic to avoid the bad date excepti Eg. aug/last/2011 +months(1)= sep/30/2011 aug/31/2000 +months(1)=sep/31/2000 //invalid date bad date excep thrown month arithmetic Month arithmetic is quite complex compared to day arithmetic since number of are not fixed . (month day <=28 || month day =last day ) always add month month day =29 cheak for leap year and than add month Month day>=30 add but don’t add if resulting month is feb Using constant objects for month arithmetic. year arithematic Always add year to date considering the condition of leap year Reversal of date back to original date Usage of last day during year arithematic 3) InterConversion field representation & serial representation Some operation are quite fast on field but airthematic operation are much faster on serial campared field representation .So it is necessary to provide the inter-coversion so that it can be easily converted from one representation to another. Constructing bi-directional conversion of serial and field by making use of memoization optimization techinique. 4)Gregorian calendar implementation This Gregorian calendar will be a hybrid calendar that support both Julian and Gregorian calendar with a single discontinuity(the day on which Gregorian calendar was adopted ).The only difference between gregorian and julian is leap year calculation and before day of adoption of Gregorian calendar ,Julian calendar is implemented in this date library. The concrete draft for implementation for calendar template< typename ymd_type ,type name date _int _type > class gregorian_calendar { public : typedef ymd_type ymd _ type ; typedef typename ymd_type : : month_type month_ type ; typedef typename ymd_type : :day_type day_type ; typedef typename ymd_type : : year_type year_type ; typedef date_ int _type date_int_type ; static unsigned short day_of_week (const ymd _type &ymd ) ; static int week_number (const ymd_type &ymd ) ; static date_int_type day_number(const ymd_type &ymd ) ; static ymd_type from_day_number(date_int_type) ; static date_int_type julian_day_number(const ymd_type &ymd) ; static bool is_leap_year(year_type) ; static unsigned short end_of _month_day( year_type y ,month_type m ) ; static ymd _ type epoch() ; static unsigned short days _ i n _week(); }; 5)Building date iterator ,date output and date input Date Iterator will generate the date based on initial condition and end.Bidirectional iterator will do all the generation of series of date.Various iterators which will be implemented are day ,week ,month ,year Iterator. date output same as H. Hinnant. Questions: 1)could you explain us why do you think a class template date is a good alternative? i am using the template class since it will implement the user extensibility .This is very important feature for developer but not for normal user because developer likes to customise code it will give them to add or modify without removing features. 2) What is the expected service of the concrete classes? Which concrete representations would you provide? i have made the concrete class to show some of details of the date library which i am going to implement . <template date_concrete> class date_pre { /*year, month,week day construction of date_field i.e serial and field based reprasentation*/ /*details of constructor 1)date_pre(); //default constructor to initialise the date with the initial default value set 2)date_pre(year_type year,month_type month,day_type day); /*this constructor will initialize the date with values given by the user . but the constructor argument arrangement can be differ according to user or the country date format used */ 3)date_pre(year_type year,month_type month,week_of_month_type week_number,weekday_type wd); //this will constructs the date like monday in week 20 of 2013 4)date_pre(special day sp); //this will day construct the date with the special values like mothers day ,christmas in year //basic accessors declaration //conversion accessors //airthematic operation //camparison operator for date camparison //Coversion of calendar }; these all same as in H. Hinnant proposal except the conversion of Julian calendar to gregorian calendar . 3) How would you implement the memoizer for conversions? Would it be thread safe? Could you post an example how your date_pre and gregorian claendar classes are used? in summary, how your proposal improc-ves H.H implementation or my prototype? since pre semester are going so can i answer to this 2 question after coming tuesday ie 7 may 2013 sorry again for not answering ur questions i will try to be active on the mailing list during my pre semester xam Thanking You Shamsher Ahmed

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[gsoc-2013] Physics Library Abstraction Layer
by Preston Hamlin 04 May '13

04 May '13

Attached is my current proposal in PDF format, as I am a bit wary of pasting several pages worth of formatted text into an email. Well wishes, -Preston

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GSoC 2013 Boost mentors discussions
by Vicente J. Botet Escriba 04 May '13

04 May '13

Hi, I would like to share privately some comments with the GSoC 2013 Boost mentors. How can we do it? How to know who is a mentor? Do we have a know e-mail for all of them? Best, Vicente

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Re: [boost] [operators] moving forward use return by reference for compilers with proper support?
by Niall Douglas 04 May '13

04 May '13

> Operators returning rvalue references are NOT safe. The C++98/03/11/14+ rules > apply to this scenario: > > X temporary(); > const X& r = temporary(); // ok, lives as long as r does > X&& r2 = temporary(); // ok, lives as long as r2 does > > They do NOT apply to this scenario: > > X&& func(X&& x) { return std::move(x); } > const X& r3 = func(temporary()); // DANGLING REFERENCE > X&& r4 = func(temporary()); // DANGLING REFERENCE > > The Standardization Committee made this mistake when applying rvalue > references to string's operator+(), which was fixed before C++11 was released. I completely agree. 99.9% of the time the only reason to *ever* return rvalue refs from an operator() is when you're passing through a parameter. Otherwise, return by value and leave the compiler's optimizer do its job. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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GSoC 2013 Bernoulli Numbers
by David Joy 03 May '13

03 May '13

Hi, I'm an Open University student completing my Open degree this summer (CompSci / Pure- & Applied Maths / Classical History) and am very interested in the Bernoulli numbers project for the Google Summer of Code. As well as the OU I've done quite a bit of mathematics elsewhere (Durham and KCL). Enclosed is my (naive) response to your challenge to implement the Akiyama–Tanigawa algorithm. I use the Boost framework for rational numbers, so as not to lose precision (though haven't yet adapted the solution for arbitrary precision numbers). [It would be more aesthetically pleasing if I could write the main algorithm in a STL-style so that it iterates of the vector, rather than explicitly using an index.] I have yet to get to grips with Boost.Test, but the enclosed shell script can generate a list of results, which matches the table found on the Bernoulli Number Page <http://www.bernoulli.org/> out to B_20. All code criticism gratefully accepted, David Bernoulli.cpp <http://boost.2283326.n4.nabble.com/file/n4646219/Bernoulli.cpp> Bernoulli_test.sh <http://boost.2283326.n4.nabble.com/file/n4646219/Bernoulli_test.sh> -- View this message in context: http://boost.2283326.n4.nabble.com/GSoC-2013-Bernoulli-Numbers-tp4646219.ht… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Re: [boost] GSoC Boost.Multiprecision project
by Jyotesh Choudhari 03 May '13

03 May '13

Hello, > Hi Jyotesh. >> Thank you for your valuable feedback. I have written >> project proposal for the first time in my life. So, I did >> not know what details to include. I have made some >> changes to my proposal as per your suggestions. > The proposal is a lot better. Now you need to submit > it to Google's melange site. > Please note that the proposal must be submitted > to Googles melange site. Some candidates have > been sending the proposals directly to us, and > this is incomplete. I have uploaded my proposal on http://www.google-melange.com/gsoc/proposal/review/google/gsoc2013/jyoteshr… >> I was studying the code for cpp_bin_float and I >> have some doubts in my mind. >> 1. What are eval_ops_signed_type, eval_ops_unsigned_type and >> eval_ops_float_type? > Eval-ops are the global binary arithmetic operatory, > and the eval_ops-types are those types that will be > supported for global binary math with the radix-2 > back-end. >> 2. What is the use of following lines? >> typedef mpl::list<eval_ops_signed_ type>? signed_types; >> typedef mpl::list<eval_ops_unsigned_type> unsigned_types; >> typedef mpl::list<eval_ops_float_type>? ? float_types; > It's Boost's way of creating a list of built-in types. > Again, these are the types that will be supported for > global binary math. >> These are not used in the class elsewhere. Similar lines >> are present in cpp_dec_float.hpp also and not used >> elsewhere in the class. > They are used by the multiprecision::number front-end > to actually implement global binary math ops. >> 3. In the function from_float_type, I think the variable >> number_of_digits should be initialized to zero before >> using it in while loop. > cpp_bin_float is in a rudimentary state right now. > It is not even close to working. That's the point of > the GSoC project. So stuff might not be quite right > yet. Thank you solving my doubts. I will see the code multiprecision::number also to see how above types are used. >> Lastly, I have seen on mailing list, that some of the >> students are submitting code samples. > It's too late for code. Get your best shot at a good > proposal onto melange. If you would like to submit > code sample, you can do it after your proposal is up. > Good luck. > Sincerely, Chris. Thanks and regards, Jyotesh Choudhari

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Voronoi benchmark update
by Sebastien Loriot 03 May '13

03 May '13

Hello, I'm involved in the CGAL Project, and saw the Voronoi benchmark. It would be nice if you could change the CGAL code slightly, as it is not as bad as it currently seems. Attached is the diff to the trunk of boost. Concerning the Voronoi diagram of points, a CGAL user, would use the Delaunay_triangulation_2 class. Concerning the Voronoi diagram of segments (that do not intersect) one would make a better choice for number types and traits classes. Also one better first inserts the endpoints and then the segments (I agree, this should definitely go into a member function). Admittedly our examples could be better. Cheers, Sebastien

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[gsoc-2013] Physics Library Abstraction Layer
by Preston Hamlin 03 May '13

03 May '13

On Sun, Apr 21, 2013 at 9:37 PM, Michael Marcin <mike.marcin(a)gmail.com>wrote: > On 4/19/2013 8:59 PM, Preston Hamlin wrote: > >> >> I have completed a draft proposal and would appreciate some feedback: >> >> https://www.dropbox.com/s/**7xhha0a3ahk5p6r/preston_** >> hamlin_gsoc_proposal_draft.pdf<https://www.dropbox.com/s/7xhha0a3ahk5p6r/preston_hamlin_gsoc_proposal_draf…> >> >> >> > Seems like a fine proposal. > > Do take note of boost coding guidelines. > > -- > Use the naming conventions of the C++ Standard Library (See Naming > conventions rationale): > > * Names (except as noted below) should be all lowercase, with words > separated by underscores. > * Acronyms should be treated as ordinary names (e.g. xml_parser instead of > XML_parser). > * Template parameter names begin with an uppercase letter. > * Macro (gasp!) names all uppercase and begin with BOOST_. > -- > > http://www.boost.org/**development/requirements.html#**Guidelines<http://www.boost.org/development/requirements.html#Guidelines> > > Prefer object interfaces to pointers. > > For example instead of: > bxPhysics* physics(___); > > prefer: > boost::physics::physics physics_(____); > > Although on second thought naming might need some more thought here. > > What exactly is it that PxCreatePhysics creates? Is it a physics context > like an OpenGL context? Is it more like a physics service like a > boost::asio::io_service? Is it a physics simulation? Is it physics object > factory? > > I'm not sure but I think it's almost certainly not just a physics. > > > In any event it looks good to me. > > My apologies for the belated response. With ACM duties and finals week I have had no more than a few minutes to sit down. I typically try to follow the Google style guide for coursework and the like, so changing naming conventions is but a minor change. The PxPhysics object is used to create and maintain a "realm" of physics. It keeps track of collision methodologies and is essentially the backbone of how edges and vertices interact with one-another. It is build on top of a PxFoundation object which provides the "foundation" of the program, including callback management and some behind-the-scenes memory allocation. The PxScene object manages the elements of a particular "scene" or "world" including pointers to the various objects and gravity. I am not sure how (other than routing messages between objects) boost::asio::io_ would provide much of anything in terms of physics. It is similar to a context like a Device Context or OpenGL Rendering Context but is not used directly and instead used in the creation of more modular objects which are linked to it upon creation. There are no built-in emitters (something that could be provided in this project) and the documentation states that the non-fluid particle system uses rigid bodies that interact with the world but not eachother, which makes sense. I was unsure how prefixes should/would be used in a project like this, which is why I used the "bx" prefix. One thing to note is that PhysX uses a 3-vector class to hold vector data. It is pretty basic but also moderately fleshed out in the source. Would compatibility with the uBLAS matrices (as vectors are to be consolidated) be desirable? The PhysX design uses pointers for just about everything, so that could mean some interesting design considerations. I will be spending the Summer assisting one of my professors with his research project (half-time) and will update my proposal accordingly. Also, if I have some free time this weekend, I can crank out some *rough* proof of concept code if it is desired. Many thanks, -Preston

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[GSOC 2013]Boost.Math Proposal
by Nikhar Agrawal 03 May '13

03 May '13

Hi everyone, I have been in touch with mentors for the project "Boost.Math Bernoulli Numbers and Applications to Special Functions" for the past three weeks. And after regular interactions and assignments and suggestions from them, I have finally posted my proposal. I was a little late because in submitting the proposal because of my end semester examinations. But that now they are over, I have all the free time to completely concentrate on the project. Here's the link to the proposal. http://www.google-melange.com/gsoc/proposal/review/google/gsoc2013/nikhar/1 I'd be really grateful if you guys could review it and suggest improvements. Thanks a lot. :) Nikhar P.S.:- If anyone wants I could also forward the conversations I've had with the mentors until now and I could upload the assignments I've done if anyone's interested.

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[gsoc-2013] proposal for approximate string matching
by Yu Jiang 03 May '13

03 May '13

Hi, I'm a student from Tsinghua University in china and interested in the idea about "approximate string matching". Below is my proposal for this. Could you please view it and give me any kinds of suggestions on it? Thanks! (1) Personal Details * Name: Yu Jiang * College/University: Tsinghua University, China * Course/Major: Computer Science and Technology * Degree Program: M.Sc. * Email: sunlightt07(a)gmail.com * Homepage: do not have one * Availability: - How much time do you plan to spend on your GSoC? Since I have a long summer holiday, I can spend 30 hours a week. - What are you intended start and end dates? I will follow the calendar of GSoC. I have plenty of time from June to September. - What other factors affect your availability (exams, courses, moving, work, etc.)? I have some courses this term which will end before June. 15th. However, these courses don't have heavy workload, I still have enough time to work on GSoC. (2) Background Information * Please summarize your educational background (degrees earned, courses taken, etc.). I majored in Computer Science and got my bachelor degree in Tsinghua University from 2008 to 2012. I learned some basic courses such as algorithm, data structure, algebra and logic. I also learned many advanced courses such as database, operating system, network, formal language, compiler, computer architecture. Currently I'm working for my master degree. My research interest is database. * Please summarize your programming background (OSS projects, internships, jobs, etc.). This is the first time I plan to take part in an OSS projects. I have worked as an intern in Hulu, an online video website, for one year, mainly focus on frontend webpages. I have used C++ to finish many course projects, such as a simple ftp server and client, completing a tiny os and so on. Recently I am learning the new features in C++11 and get to know much more about the C++ language. * Please tell us a little about your programming interests. I really love to optimize on the implantation of an algorithm by making full use of the compiler and the architecture(e.g. cache, SIMD). Besides, I like to write webpages using different kinds of excellent frameworks. * Please tell us why you are interested in contributing to the Boost C++ libraries. Boost is the most famous C++ libraries. It is powerful and can be used in many different kinds of programs. It's my honor to add some new features into it. * What is your interest in the project you are proposing? It's related to my research interest. Nowadays data are produced rapidly. To clean or integrate them so that we can get a better view, "Approximate string matching" is rather a powerful tool. I'd like to see such functions in boost library. * Have you done any previous work in this area before or on similar projects? Yes. My lab has focused on researching on such algorithms for 3-5 years. The "best" algorithm for general string similarity search and join is called "passjoin", which is invented by our lab. I have implemented it and done a lot of optimizations. Early this year we attended a string similarity search & join competition[1] and achieved champion. The code is mainly written by me. [1] http://www2.informatik.hu-berlin.de/~wandelt/searchjoincompetition2013/Resu… * What are your plans beyond this Summer of Code time frame for your proposed work? I will make efforts to make it accepted by the boost library. If it can be released someday, I will maintain it. * Please rate, from 0 to 5(0 being no experience, 5 being expert), your knowledge of the following languages, technologies, or tools: -C++: 3 -C++ Standard Library: 3.5 -Boost C++ Libraries: 2 -Subversion: 3 * What software development environments are you most familiar with? Eclipse. I use it in both windows and linux. * What software documentation tool are you most familiar with? Doxygen. (3) Project Proposal Approximate string matching is a "hotspot" in recent years. It's widely used in big data processing such as search engine, DNA matching. It also can be used in simple tasks like spell checking. However, there isn't a high performance and well-designed library in such area. I wish to see such algorithms in boost so that many people can benefit from this! My proposal contains two parts: A. To implement basic similarity metrics. Edit distance and Jaccard may be the most popular ones. Well, I'll implement more similarity metrics, such as Hamming distance, dice and cosine. B. To implement the fastest algorithm for string similarity search and join. Similarity metrics will be edit distance only since it is most commonly used. Similarity search is to find out all the strings in a given set S, which are "similar" to a query string. Similarity join is to find out all the string pairs<r,s>, where r is in set R and s is in set S and r is similar to s. They are the most useful operators in large data processing. However, the brute-force method for such problem is too slow. And it's not easy to write a correct and high performance algorithm without reading the details in many research papers and debugging them for a long time. To avoid reinventing the wheel, I strongly propose to implement it in boost library. Here is a prototype for the interface: Part A. basic similarity metrics (use edit distance as an example) (1) int edit_distance(const Range1T&, const Range2T&); // return edit distance. (2) int edit_distance(const Range1T&, const Range2T&, int threshold); // return edit distance if it is no larger than threshold, else return -1 or threshold + 1. (3) int edit_distance(const Range1T&, const Range2T&, equal_func); // use uqual_func to determine whether two elements are equal or not. (4) int edit_distance(const Range1T&, const Range2T&, insert_cost_func, delete_cost_func, substitute_cost_func); // use three cost functions to calculate the cost for one insert/delete/substitute operation. (5) some functions to return the sequence of operations? Version (1) may be the most common case. Version (2) can use the given threshold to do optimization for the speed (O(m*n) -> O(threshold * min(m, n))). It's useful since sometimes we only care about the exact edit distance if it is small. Version (3) and (4) extend the flexibility of this utility algorithm. I'm not sure whether to support (5) or not. Part B. string similarity search and join algorithms, focus on edit distance class searcher { void insert(IDType id, const string &word); // insert a word to the index, id is used as an identifier of this word. void erase(IDType id); // erase a word from the index, id should be the same one used in insertion process. vector<Result> search(const string &query, int threshold); // performing similarity search, which will return all the strings which are similar to the query string. Result may be a pair of the id and real edit distance. }; class joiner { vector<PairResult> join(const string_and_id_container &R, const string_and_id_container &S, int threshold); // performing similarity join. Usually we are doing on-line join, which means we cannot pre-build the index. So we only need this one function. It will return all the <r,s> pair where r is in R and s is in S and r is similar to s. PairResult may be a tuple of r's id, s's id and real edit distance. }; (4) Proposed Milestones and Schedule Now – June 15 To be more familiar with the Boost library. Discuss the details and interfaces with my mentor and on the develop mail list. June 15 – July 15 Develop a beta version of the approximate matching library. Most functions will be done at this time. July 15 – August 1 Review my code and improve its performance and quality. Discuss with my mentor for mid-term evaluation and future works. August 1 – September Write documentation, test code for my library. Make it "boost" like.

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[GSoC 2013] Proposal Boost.Math Bernoulli Numbers and Applications to Special Functions
by Łukasz Marecik 03 May '13

03 May '13

Hi, I would like to introduce my proposal to project "Boost.Math Bernoulli Numbers and Applications to Special Functions". It is available at https://google-melange.appspot.com/gsoc/proposal/review/google/gsoc2013/luk… Please note that HTML version is not the best one: the formatting is not very nice, there is also lack of equations and source codes (there are provided in external files). So please take a look at PDF-version of my proposal (follow the link at Google Melange site). Kind regards, Lukasz Marecik

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GSoC: Data structures and algorithms for integer ranges.
by Jeremy Murphy 03 May '13

03 May '13

Hello Boost community, I realized almost too late (two days ago) that GSoC 2013 is happening, and that Boost is in. Obviously I have missed the boat on "engaging with the community" early, but I still plan to submit a proposal. The one thing I would love to get some brief feedback on in these last hours is scope: how much should I expect to get done in 12 weeks? Unsurprisingly, it is one of the hardest questions for an inexperienced worker in any field to answer. The core of my proposal is to implement i) a van Emde Boas tree and ii) three counting sort algorithms: "counting", radix and bucket. Is that enough? Too much? Any advice would be helpful, thanks. Cheers. Jeremy

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Google summer of code 2013
by Jawad Elomari 03 May '13

03 May '13

Hi everyone, I want to join the Google summer of code this year, for the PaGMO/PyGMO<http://www.google-melange.com/gsoc/org/google/gsoc2013/pagmo> library. I'm interested in the Racing projects, but I'm not sure which Boost library is most suitable for it. Any ideas? Regards,

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[GSoC 2013] Implicit routines in boost.odeint
by Artem Serov 03 May '13

03 May '13

Hello again! I have been working on proposal since aproximately 15 of April, investigating boost odeint, some theory of numeric methods of solving ODE and implementing a draft of the design of implicit routines. I discussed some issues privately with mentors of odeint project Mario Mulansky and Karsten Ahnert and have taken into account all the points. Here is the 1st version of the proposal for Boost.odeint implicit routines. Note: The main idea i kept in mind was to describe steps how i will do the project as clear and detailed as possible. I tried to show my acquired experince of odeint structure and concepts, my understanding of the issue and concrete ways of tackling it. Note: The proposal entirely lacks introduction, list of literature and sources! i will settle it as soon as possible. Here is the link to the proposal: https://docs.google.com/file/d/0B-2QwVSmhDBIYTB0eVZxdHhsNUE/edit?usp=sharing -- Thanks, Artem Serov

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GSoC: Student application deadline in less than 24 hours
by Boris Schaeling 02 May '13

02 May '13

Students interested in applying for a GSoC project should submit their application as soon as possible. The deadline is in less than 24 hours. Click here to apply: <https://google-melange.appspot.com/gsoc/homepage/google/gsoc2013> Boris

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[gsoc-2013] Boost.Expected
by Pierre T. 02 May '13

02 May '13

Hello, My name is Pierre Talbot, I participated to GSoC 2011 and began the implementation of the Boost.Check library (for checking the validity of any number having a check digit — credit card number, ISBN, …). It was two years ago and the design is still evolving due to many variation points in the code. One of the function looks like : template <typename check_algo, typename range> boost::optional<typename check_algo::checkdigit_type> compute_checkdigit(const range &x); Using boost::optional tell us that: "A check digit should be computed if 'x' is a valid sequence". Since 'x' has many reasons to be incorrect, many errors could be raised. Based on a policy template class, it launches exception or returns with an empty optional . Then I though a lot about a better way to do it, allowing the user to get an exception or an error code. But it was quite complex for a so little part of my library… I decided that the policy "throw exception or nothing" should be enough. Yesterday, I watched the video of Mr. Alexandrescu on Boost.Expected and I think it would be a very useful library. It could mainly be useful in system programming (where many error codes can arise from a single call), but in any code where many exception errors can be thrown (like in Boost.Check). As you suspected, I'm interested in coding Boost.Expected during the summer as a GSoC student. Firstly, it could be very useful to list the resources on the subject (aside the talk), I have several articles that I will talk about later. Secondly, and hoping you'll debate, I would like to ask your opinion about several ideas and facts: 1) In the Boost project description, we can read: "adding a class expected-or-error_code". Obviously, the main design decision made by Alexandrescu is to consider that error code are exception. Do we need an abstraction of exception/error code ? Why do you think a "expected-or-error_code" class is interesting ? 2) Consider this code (from Alexandrescu slides) : // Caller string s = readline(); auto x = parseInt(s).get(); // throw on error auto y = parseInt(s); // won’t throw if (!y.valid()) { // handle locally if (y.hasException<std::invalid_argument>()) { // ------------------ < The flagged line. // no digits ... } y.get(); // just "re"throw } The flagged line has some tastes of "return to the past" flavor. Back to the C procedural language, the basic error code handling system was a lot criticized because: * Readability of the code decrease ; * Error handling occurs in the middle of the execution flow ; * <Add your favourite reason here>. Several links on the subjects (if you have others, I'm interested) http://www.joelonsoftware.com/articles/Wrong.html http://www.joelonsoftware.com/items/2003/10/13.html http://blogs.msdn.com/b/oldnewthing/archive/2005/01/14/352949.aspx http://nedbatchelder.com/text/exceptions-vs-status.html Basically, only the last one is clearly for exception. The main argument against the procedural approach is the readability. I would say that the Expected approach just differ by allowing to rethrow exception. But if you want to handle it, you must code multiple if-than-else statements. So I considered a complementary approach working with Expected to handle multiple error cases: string visa_number = readline(); expected<char> expected_checkdigit = compute_checkdigit<visa>(visa_number); if(expected_checkdigit.valid(visa_error_resolver)) { visa_number += expected_checkdigit.get(); std::cout << visa_number << std::endl; } With this code, there is only a if statement, and no more multiple error cases handles. But what is this error_resolver ? It may be declared as : // Somewhere in visa.hpp. A type list. typedef error_list<size_error_exception, unknown_character_exception, checkdigit_encoding_exception, …> visa_errors; // Somewhere in the user code. error_resolver<visa_errors, expected_type> visa_error_resolver; // in this case, expected_type is a char. // Initialize error handler on specific exception/errors. visa_error_resolver.on<size_error_exception>(size_error_handler) .on<unknown_character_exception>(unknown_character_exception) ... Now we are agree that visa_error_resolver can be reused everywhere we want to resolve an error on a visa number. What are the handlers ? There are [Function|Functor|Lambda] (pick up your favourite) with this form : expected<ExpectedType> size_error_handler(const size_error_exception&) expected<ExpectedType> unknown_character_exception(const unknown_character_exception&) Now you can understand for what the type list "error_list" stands for, we can store these handlers into the error_resolver and call them without any virtual cost. Why the return type of error handler is expected<ExpectedType> ? Consider this size_error_handler code : expected<ReturnType> size_error_handler(const size_error_exception& e) { std::cout << "The number you gave has a bad size." << std::endl; std::cout << "Enter it again : " << std::endl; return read_visa_checkdigit(); } read_visa_checkdigit can call recursively valid() until it's valid. Though there are some ways to make this treatment iterative. A basic treatment could be to print an warning message and just returns (in this case, valid returns false): expected<ReturnType> size_error_handler(const size_error_exception& e) { std::cout << "Warning: the VISA field is incorrect." << std::endl; return expected<ReturnType>::fromException(e); } Results: * The error code handling is delegated to specific functions ; * The readability is still excellent ; * You can easily re-use your error handler function ; * If you don't like it, you can still throw exception on failure with "get()". I can code a "proof of concept" if you think this is a good idea. Do not hesitate to comment it, point out programming pitfalls, request further clarification, or anything you judge useful. Thank you for reading it ! Pierre Talbot

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 02 May '13

02 May '13

> > I have just read N3388 - Using Asio with C++11 and a think I start to > > understand the ASIO design. > > Could we say the completion handlers are continuations? > > And that the user use to master which thread executes the continuation by > > calling the io_service::run() function? > > Pretty much, except that multiple threads can call io_service::run > concurrently. Basically Boost.Asio is a work sharing queue plus a > collection of waitqueues to wait for specific events. Far clearer than my explanation. Thanks. > That's orthogonal. Boost.Asio provides the funding blocks. A nicer > interface that doesn't require an explicit continuation passing style > transformation can be built with Boost.Context or a similar library. > But it probably needs a future implementation that integrates with > ASIO, which is one of the point of Niall Douglas. Spot on. Especially as parts of ASIO are due to enter with TR2. I worry that a thread pool designed without ASIO in mind would become an orphan isolate. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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[testing] run.py and cross compilation
by Antony Polukhin 02 May '13

02 May '13

Hi, Is there some possibility to compile sources on one platform (x86) and then run compiled tests on other platform (ARM/Android) using run.py script? This is required, because Android SDK exists only for x86 so there is no way to compile tests on ARM Android device. -- Best regards, Antony Polukhin

2 3

[GSoC2013] My updated proposal to the XML library project
by Amos Ji 02 May '13

02 May '13

Hi, I have updated my proposal to the XML library project. If you're interested in it, you can review it at http://www.google-melange.com/gsoc/proposal/review/google/gsoc2013/amosji/3… And there is also a pdf version: https://www.dropbox.com/s/3zgxkpb9bx45auo/Boost_XML_library.pdf Any comments are appreciated. Thanks a lot. Regards, Mingchao

1 0

[reference_wrapper] Overloading operator() in reference_wrapper
by Nathan Crookston 02 May '13

02 May '13

Hi all, std::reference_wrapper includes an overload of operator()[1] which allows a wrapped function object to be called without needing to first unwrap: #include <boost/ref.hpp> #include <functional> #include <iostream> int main() { auto f = [](int i) { std::cout << i * 2 << std::endl; }; std::ref(f)(5);//change this to boost::ref and it will not compile. } I think it would be valuable to update boost::ref to match the standard version. On compilers which support variadic templates and rvalue references the code is obvious. Those which support one or neither could still have overloads for some number of arguments. This would be handy in a few places, notably boost::gil::for_each_pixel[2]. I know that boost::bind + reference wrapper could be used instead (boost::bind(boost::ref(f), 5)). Given that implementing operator() is relatively simple, and that the standard object based on boost::reference_wrapper has it (rather than requiring std::bind), I'd argue that this change is desirable. Thanks, Nate [1] http://en.cppreference.com/w/cpp/utility/functional/reference_wrapper/opera… [2]http://comments.gmane.org/gmane.comp.lang.c%2B%2B.isocpp.general/513

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 02 May '13

02 May '13

> Le 01/05/13 20:39, Niall Douglas a ?crit : > >> I don't see the term "central asynchronous dispatcher" used in any of > >> the links. Could you clarify what it is? > > I have to admit I'm struggling to see where your block is, but Dave Abrahams > > often found the same with me, so it must be me. > It is just that I don't know the term. > As I don't know the domain (the words) you are talking about we can stop > the exchange here if you prefer, or you could continue to explaining me > the things I don't know/understand. Don't worry, it's almost certainly me as native English speakers rarely understand me either. Besides when I lived in Spain I remember only too well the problem with domain terminology, like when a dentist told me I had a "del gasto" which I took to him wanting money because he had high rent :). I'll keep going as long as you need. We'll get there eventually. > > The central means one execution context does the dispatch. The asynchronous > > means that callbacks are processed by recipients asynchronous to the > > dispatcher. And dispatcher, well that dispatches. > In order to be sure I understand what you say could you tell me how a > decentralized asynchronous dispatcher behaves? What are the differences? A centralized dispatcher dispatches from one execution context to many. A decentralized dispatcher dispatches from many execution contexts to one or more contexts. An example of the latter is cloud apps actually, where millions of apps will dispatch events to a load balanced core cluster of servers i.e. many => few. By execution context I mean a thread, a fibre, a coroutine, a handler or even a closure. Generally if it's got its own distinct stack separate from other stacks, it's an execution context. > > I'd take a reasonable guess that MCAS will benefit centralized kernel-based > > threading primitives architectures such as Windows NT more than > > decentralized threading primitive architectures such as POSIX. That said, I > > could see Linux using TM for batch multi-kernel-futex ops, though I'd have > > to say implementing that without breakage would be daunting. > > > Are you saying that current TM technology should be much more useful for > centralized than decentralized asynchronous dispatchers? I'm saying my suspicion is that. Others on SG5 may disagree (they disagree with me about most of my opinions). It's still very early days for TM in C++. > Does this means that the whole application would improve its > performances using always centralized asynchronous dispatchers? I'm saying it's a likely optimization case. Other than a recompile, application need not know the difference. > > You may find N3562 Executors and schedulers coproposed March 2013 for > > Bristol by Google and Microsoft of use to you in understanding the relation > > between thread pools and Boost.ASIO > > (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3562.pdf) > I know this proposal. Could you explain me how it is related to > Boost.Asio? Could you point me where in the Asio documentation could I > find related information? I think your other post is more relevant, so I'll answer there. But agreed that Asio's documentation assumes the user already understands how it works. If you come from a NT kernel or VMS or libuv programming background, it's obvious. But much less so for everyone else. > > My > > proposed Boost.AFIO library is an implementation of that same N3562 idea, > > albeit I extend Boost.ASIO which is IMHO more C++-y whereas Google and > > Microsoft have gone with proprietary implementations. Also, they include > > timing and many other more general purpose features, and mine does not > > (currently) as it's mainly aimed at maximising input/ouput with highly > > jittery random latency storage. > > > Thanks Niall for all the explanations and sorry if all this is trivial > for you. These types of discussion always add to the collective good. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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[testing] run.py and cross compilation
by Niall Douglas 02 May '13

02 May '13

> Is there some possibility to compile sources on one platform (x86) and > then run compiled tests on other platform (ARM/Android) using run.py > script? > > This is required, because Android SDK exists only for x86 so there is > no way to compile tests on ARM Android device. I believe we have a related or similar problem with unit testing Boost on BB10. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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[gsoc2013] Proposal for Boost.Math Bernoulli numbers and special functions project
by Artemy Margaritov 02 May '13

02 May '13

Hi folks! I want to provide my proposal for Boost.Math Bernoulli numbers and special functions poject to the Boost community. Please, lets discuss it! I will be grateful for your advices. -- Best regards, Artemy Margaritov

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Re: [boost] [gsoc-13][proposal] Boost.uBLAS
by Aditya Avinash 02 May '13

02 May '13

On Thu, May 2, 2013 at 1:24 AM, Aditya Avinash <adityaavinash143(a)gmail.com>wrote: > I have updated the proposal. Here it is. > > > On Thu, May 2, 2013 at 1:21 AM, Aditya Avinash <adityaavinash143(a)gmail.com > > wrote: > >> Hi, this is my GSOC 13 proposal on Boost uBLAS. >> >> >> On Wed, May 1, 2013 at 3:15 PM, David Bellot <david.bellot(a)gmail.com>wrote: >> >>> Great. I'm looking forward to it. >>> >>> Best, >>> David >>> >>> >>> On Tue, Apr 30, 2013 at 11:06 PM, Aditya Avinash < >>> adityaavinash143(a)gmail.com >>> > wrote: >>> >>> > I'll upload in 16 hrs. >>> > >>> > On Wed, May 1, 2013 at 2:55 AM, David Bellot <david.bellot(a)gmail.com> >>> > wrote: >>> > >>> > > Hi Aditya, >>> > > >>> > > yes, please send me a written proposal, so that I can help you on >>> that. >>> > > It's definitively something we want to do for ublas. >>> > > >>> > > Best, >>> > > David >>> > > >>> > > >>> > > On Mon, Apr 29, 2013 at 6:56 PM, Aditya Avinash >>> > > <adityaavinash143(a)gmail.com>wrote: >>> > > >>> > > > Hi, I have a proposal for boost in gsoc-13 under boost.ublas >>> > > > >>> > > > *Proposal: SIMD abstraction for uBlas.* >>> > > > >>> > > > >>> > > > - I want to develop SIMD abstraction for uBlas. >>> > > > >>> > > > >>> > > > Goal 1: Develop the Intel SSE & AVX backend for SIMD abstraction in >>> > > uBLAS. >>> > > > >>> > > > Goal 2: Develop AMD SSE backend for SIMD abstraction in uBLAS. >>> > > > >>> > > > Goal 3: Develop frontend for SIMD abstraction in C++. >>> > > > >>> > > > Goal 4: Joining of frontend and backend, so the the code is >>> flexible to >>> > > > implement on both AMD and INTEL. >>> > > > >>> > > > Goal 5: Develop the ARM-NEON backend for SIMD abstraction in >>> uBLAS. >>> > (if >>> > > > time permits). >>> > > > >>> > > > -- >>> > > > ---------------- >>> > > > Atluri Aditya Avinash, >>> > > > India. >>> > > > >>> > > > _______________________________________________ >>> > > > Unsubscribe & other changes: >>> > > > http://lists.boost.org/mailman/listinfo.cgi/boost >>> > > > >>> > > >>> > > _______________________________________________ >>> > > Unsubscribe & other changes: >>> > > http://lists.boost.org/mailman/listinfo.cgi/boost >>> > > >>> > >>> > >>> > >>> > -- >>> > ---------------- >>> > Atluri Aditya Avinash, >>> > India. >>> > >>> > _______________________________________________ >>> > Unsubscribe & other changes: >>> > http://lists.boost.org/mailman/listinfo.cgi/boost >>> > >>> >>> _______________________________________________ >>> Unsubscribe & other changes: >>> http://lists.boost.org/mailman/listinfo.cgi/boost >>> >> >> >> >> -- >> ---------------- >> Atluri Aditya Avinash, >> India. >> > > > > -- > ---------------- > Atluri Aditya Avinash, > India. > -- ---------------- Atluri Aditya Avinash, India.

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[gsoc 2013] draft proposal for chrono::date
by Anurag Kalia 02 May '13

02 May '13

I have prepared a draft proposal for Boost.chrono/date implementation. Could you kindly go through it and tell me of any errors and suggestions? Regards, Anurag Kalia.

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Proposal for Bernoulli numbers
by Gaurav Deshmukh 02 May '13

02 May '13

Mentors for Boost.Math, please review my proposal at the melange site. http://www.google-melange.com/gsoc/proposal/review/google/gsoc2013/gaurav42… Shall I include details about the templates of functions I will have to implement? Or are there any corrections or details needed? Thanking you, Gaurav Deshmukh

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[GSOC] Are we going to participate?
by Antony Polukhin 02 May '13

02 May '13

Hi all, Today starts Google Summer of Code. Is Boost community will become one of the mentoring organizations? What project ideas are we proposing? (As for me, I'd love to see unique_ptr+unique_array implemented using Boost.Move; C++11 features support for MPL, Fusion, Graph, Bind, Optional; BTree library; library for getting system info) -- Best regards, Antony Polukhin

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[Log] Plans to use std::thread?
by Rich E 01 May '13

01 May '13

Hi all, As I've been testing out the newly added Boost.Log library, I noticed it is relying on Boost.Thread even when the C++11 <thread> library is present. Are there any plans to allow the native <thread> library to be used when it is available? I think this can be done with Boost.Config's BOOST_NO_CXX11_HDR_THREAD macro. Thanks, Rich

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Re: [boost] GSoC Boost.Multiprecision project
by Jyotesh Choudhari 01 May '13

01 May '13

Hello, > Hi Jyotesh. >>>> Looking at the project description, I think >>>> I have understood what needs to be implemented >>>> in this project. > Yes, you seem to have a good grasp of the issues. > Good work. >>>> I have also gone through the current >>>> code cpp_bin_float.hpp and I have understood some >>>> part of it. I want to know how >>>> detailed should my proposal be? What details >>>> should I include in my proposal? >>>> What should be the deliverables for the project? > Go ahead and add some details from cpp_bin_float > if you like. You can mention that this is a potential > solution method. Thank you for your valuable feedback. I have written project proposal for the first time in my life. So, I did not know what details to include. I have made some changes to my proposal as per your suggestions. > Other than that, I believe you have found > the right level of detail, with a few more suggestions > from my side below. >> I have attached my proposal with this mail. >> Please have a look at it and let me know your feedback. >> Thanks and regards, > I suggest you move the FFT algorithms to an optional > part, add a bit more time for the elementary transcendental > functions, and add some time for testing the various > milestones in the project. > After that, you should start submitting your proposal. > As far as I know, you can modify your proposal up > to May 03. I have written FFT algorithm as an optional algorithm now and made some changes to schedule. Please let me know if it is fine now. > Keep up the good work. > Sincerely, Chris I was studying the code for cpp_bin_float and I have some doubts in my mind. 1. What are eval_ops_signed_type, eval_ops_unsigned_type and eval_ops_float_type? 2. What is the use of following lines? typedef mpl::list<eval_ops_signed_type> signed_types; typedef mpl::list<eval_ops_unsigned_type> unsigned_types; typedef mpl::list<eval_ops_float_type> float_types; These are not used in the class elsewhere. Similar lines are present in cpp_dec_float.hpp also and not used elsewhere in the class. 3. In the function from_float_type, I think the variable number_of_digits should be initialized to zero before using it in while loop. Lastly, I have seen on mailing list, that some of the students are submitting code samples. As I am busy with my end-semester exams and R&D project, I am not able to send any sample code. As soon as I get free, I will send it. Thanks and regards, Jyotesh Choudhari

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[gsoc-13][proposal] Boost.uBLAS
by Aditya Avinash 01 May '13

01 May '13

Hi, I have a proposal for boost in gsoc-13 under boost.ublas *Proposal: SIMD abstraction for uBlas.* - I want to develop SIMD abstraction for uBlas. Goal 1: Develop the Intel SSE & AVX backend for SIMD abstraction in uBLAS. Goal 2: Develop AMD SSE backend for SIMD abstraction in uBLAS. Goal 3: Develop frontend for SIMD abstraction in C++. Goal 4: Joining of frontend and backend, so the the code is flexible to implement on both AMD and INTEL. Goal 5: Develop the ARM-NEON backend for SIMD abstraction in uBLAS. (if time permits). -- ---------------- Atluri Aditya Avinash, India.

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 01 May '13

01 May '13

> Le 29/04/13 21:35, Niall Douglas a ?crit : > > No major changes to the C++11 futures API is needed. Rather that a > > different, but compatible, optimized implementation of future<> gets > > returned when used from a central asynchronous dispatcher. So the C++ > > standard remains in force, only the underlying implementation is more > > optimal. > > Could you explain me what a central asynchronous dispatcher is? An asynchronous procedure call implementation. Here's Microsoft's: http://msdn.microsoft.com/en-us/library/windows/desktop/ms681951(v=vs.85).as px. Here's QNX's: http://www.qnx.com/developers/articles/article_870_1.html. Boost.ASIO is the same thing for Boost and C++ but implemented by application code. It is *not* like asynchronous POSIX signals which are a nearly useless subset of APCs. > If not, please could you elaborate what kind of optimizations can be > obtained? If you have transactional memory in particular, you gain multi-CAS and the ability to (un)lock large ranges of CAS locks atomically, and a central dispatcher design can create batch lists of threading primitive operations and execute the batch at once as a transaction. Without TM, you really need the kernel to provide a batch syscall for threading primitives to see large performance gains. > > Futures come in because you'd naturally use std::packaged_task<> with > > Boost.ASIO. It returns a future. > Could you point me to the Networking paper proposal that has > packaged_task<> on its user interface. I would expect this to be an > implementation detail. You misunderstand me. *If* you want Boost.ASIO to dispatch unknown std::function<>, *then* std::packaged_task<> is the most obvious route forwards. And the correct way to pass a value from one execution context to another is std::future<>. This includes the single threaded case e.g. when going through a C++ -> C -> C++ transition as a stack unwinds. > > For reference, the AFSIO/AFIO project is *not* a threadpool. It's a batch > > asynchronous execution engine based on Boost.ASIO that lets you chain, in > > vast numbers, huge arrays of std::function<> whose returns are fetched using > > std::future<> to be executed asynchronously according to specified > > dependencies e.g. if A and B and C, then D, then E-G. That sort of thing. > So the thread pool you need is an internal one that is adapted to you > particular needs, isn't it? I think you don't understand what Boost.ASIO is or how it works. Boost.ASIO's core is boost::asio::io_service. That is its dispatcher implementation which each dispatch execution context being executed via boost::asio::io_service::run() which is effectively an event loop. Third parties then enqueue items to be dispatched using boost::asio::io_service::post(). You don't have to run Boost.ASIO using multiple threads: it can be single threaded. So is my thread pool an internal one adapted to my particular needs? In the sense I need not use threads at all, yes. In the sense that boost::asio::io_service's use scenario is inviolate, no. Boost.ASIO has its API, and you have to use it. And Boost.ASIO's API will be similar to the TR2 networking API. There is nothing stopping a person merging a Boost.ASIO managed thread pool with a traditional thread pool. I would struggle to see the use case though - this would an excellent thought project actually which would benefit any Boost.ThreadPool. > > One thing presently implemented on that engine is asynchronous file i/o, but > > in the next month or two you'll hopefully see batch parallel SHA256 using > > 4-SHA256 SSE2 and NEON implementations also added to the asynchronous > > engine. The idea is that the engine is fairly generic for anywhere where you > > do need to chain lots of coroutine type items together (not that it supports > > Boost.Coroutine yet). v1 isn't particularly generic nor optimal, but I'm > > hoping with feedback from Boost that v2 in a few years' time would be much > > improved. > > > As Oliver noted you could take a look at Boost.Fiber and Boost.Task. Right now anything Boost.Context based can't have multiple contexts simultaneously entering the kernel apart from on QNX and possibly Hurd. Therefore, for the time being, full fat threads are the only thing being considered. If kernel support ever includes coroutines or fibres, that will be eagerly added (I like coroutines, I use them a lot on Python). Note that on async i/o capable platforms multiple threads are solely used for non-async APIs like batch directory creation and batch chmod. Normal i/o gets multiplexed using completion handlers. Currently on Windows for example, threads are barely used at all. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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Re: [boost] [operators] moving forward use return by reference for compilers with proper support?
by Andrew Ho 01 May '13

01 May '13

> They do NOT apply to this scenario: > > X&& func(X&& x) { return std::move(x); } > const X& r3 = func(temporary()); // DANGLING REFERENCE > X&& r4 = func(temporary()); // DANGLING REFERENCE Hmm, I see. sub-clause of 12.2 clause 5: > The lifetime of a temporary bound to the returned value in a function return statement (6.6.3) is not extended; the temporary is destroyed at the end of the full-expression in the return statement. I presume there must be some implementation detail on why a returned temporaries' lifetime can't be extended. Too bad, looks like return by value is the best option available.

1 0

[operators] moving forward use return by reference for compilers with proper support?
by Andrew Ho 01 May '13

01 May '13

Following some feedback I got from MS about the disparity between VS2012 and GCC/Clang in how some the lifetimes of temporaries are handled, it appears that going forward (possibly C++14) overloading operators in the same fashion as Dfrey operators should be safe. For reference, these overloads for a single argument commutative operator are: T operator OP(const T&, const T&); T&& operator OP( T&& lhs, const T& rhs); T&& operator OP( const T& lhs, T&& rhs); T&& operator OP( T&& lhs, T&& rhs); They referred me to http://www.open- std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf (draft of C++ standard), which in section 12.2, clause 5 says that a temporary's lifetime is extended to the lifetime of the reference it is bound to. I checked draft n3376 (latest publicly available draft as of today), and the same clause was present. This is the current behavior in VS2012 and it's likely that future compilers will support this as well. Should we start tracking which compilers do exhibit this behavior in Boost.Config and use the return by rvalue ref code if proper compiler support is available? I know these are just working drafts and can change in the future, but I can't think of a reason why they would remove this clause from the C++14 standard, or of any test cases which would cause a program to fail assuming this clause is properly implemented. We'll have to provide an implementation which supports return by value as well for compilers which don't support this clause, and possibly a third implementation for compilers which don't support move semantics at all, though I have demonstrated that Boost.Move can be used to merge these latter cases.

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GSoC 2013
by Anoop C S 30 Apr '13

30 Apr '13

I wish to participate in GSoC 2013 along with the Boost C++ libraries. I plan to take up the problem of Unified Representation of Vector and Matrix into a unique matrix class. Which of the Boost libraries are to be studied thoroughly inorder to achieve the goal. I already started reading Boost Documentation.

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[GSoC 2013] Boost.Math Bernoulli Numbers and Applications to Special Functions
by Łukasz Marecik 30 Apr '13

30 Apr '13

Hi, My name is Lukasz Marecik, I am fifth year student of Mathematics and fourth year student of Computer Science at Warsaw University. I would like to apply to Google Summer of Code 2013 project. I am interested in Bernoulli Numbers and their applications. While thinking about this project and doing some research, I collected some questions and issues, which I would like to discuss with my (potential) mentors. The answers can have strong influence at my official proposal. 1. Is (one of) the goal of this project to implement FROM SCRATCH completely new boost library, which will calculate Bernoulli Numbers ? I have already found two great C++ open-source programs: - http://www.bernoulli.org/ - http://web.maths.unsw.edu.au/~davidharvey/papers/bernmm/ They are already extremely efficient and fast (the funny thing is that they use completely different approach). Can boost project include and adapt one of them ? Why not ? 2. Are we going to implement only precise calculation of Bernoulli numbers or also Bernoulli numbers modulo p (where p is prime) ? 3. How the implementation of method of computing Bernoulli numbers will look like? Will it be a big template which works with all (reasonable) types (built-in, multiprecision) in the same way ? I was thinking for a while about this and I think it would be better to implement separately computing rational Bernoulli numbers (e.g. gmp_rational type) in a modern way: compute B_n modulo a lot of small primes and then reconstruct B_n via Chinese Remainder Theorem. This algorithm is one of the faster for this concrete type: precise rational numbers, but (in my opinion) it will be inefficient, when we want the output be built-in types. I do not know if I express precise what I want. For example: naive Akiyama–Tanigawa algorithm does not assume the type of output: the calculation can be performed at any type. Will our library work with all types in the same manner, or will our library run different algorithms and choose which one is better in this concrete case ? 4. Do I need to make my own research, reads papers about Bernoulli numbers, find the best practical algorithm and then propose it to my mentor or my mentor will help me to find and choose algorithm ? (so: Can I rely on myself only ?). Until now I have found three interesting approach: - use Chinese Remainder Theorem (described above) - use Euler's formula and the zeta-function algorithm - use completely new subquadratic algorithm (the paper was "submitted to publication", but it was not published in magazine until now ; it is online) The first two of them all already implemented and work (I think) in O(n^(2+eps)) time (it is good to mention that we need \theta(n log n) bits to represent precise number). The third one had (asymptotically) better complexity, but it goes throw a lot of complicated Maths, p-adic numbers etc and it has been not implemented yet - so it can turn out that the constant hidden in Big O notation is so big, that it is unpractical. But who knows. Do I need to discuss in my proposal different approach ? 5. Do I need to include in my proposal some words about applications to boost function: - theoretical view: where bernoulli numbers appear - practical view: how those functions are implemented now and how there will be implemented - and why they will be better ? I am sorry, that I am writing so late, but I was not sure for a long time if I want to apply ; I hope I finish my proposal in time. Kind regards, Lukasz Marecik

2 1

[type_traits] boost::decay vs std::decay
by Agustín K-ballo Bergé 30 Apr '13

30 Apr '13

Hello, It has been pointed out before that `boost::decay` and `std::decay` are not exactly the same. The standard does remove CV qualifiers while boost doesn't. See https://svn.boost.org/trac/boost/ticket/7760 I would like to know if there is a resolution on this issue. If the difference is intentional, then I suggest a note be added to the documentation. I could prepare a patch either way. Regards, -- Agustín K-ballo Bergé.- http://talesofcpp.fusionfenix.com

1 0

GAL (Generic Audio Library) based on GIL
by Brendon Costa 30 Apr '13

30 Apr '13

I am looking into the possibility of developing a library based on the same concepts and a similar interface to Boost.GIL call Boost.GAL. The idea is simply to define something very similar to GIL but for audio processing instead of image processing. Most of the concepts in GIL map almost 1 to 1 to audio processing as well. What are peoples thoughts on such a project? Is there anything in Boost.GIL that we have learn't from that should be done differently? --- Basic Premise --- The base concepts for GAL are described below and shown are the direct equivalents in the GIL library: * GAL.Sample ~= GIL.Channel Represents the amplitude of a single audio sample (float32, int16, ...) * GAL.SampleTime ~= GIL.Point Identifies the "time" a sample was taken (in units of the SampleRate) * GAL.Channel ~= GIL.Colour Identifies an audio channel location (FRONT_LEFT, or FRONT_RIGHT might be a channel for example) * GAL.ChannelMapping ~= GIL.Colour-space Maps channels to specific layout in memory (offset 0 is FRONT_LEFT, ...) * GAL.Frame ~= GIL.Pixel Identifies a single time slice (multiple channels for single sample point in time) * GAL.Block ~= GIL.Image Identifies a 1D sequence of Frame's * GAL.SampleRate ~= GIL.PPI I don't think GIL has this concept at the moment, but would be similar to Pixels Per Inch in the image world * GAL.Layout ~= GIL.?? This is the same in GIL and GAL the memory layout can be interleaved or not (planar for GIL) * GAL.Format ~= GIL.?? I don't think GIL has this concept at the moment but it represents the format of data without actually storing any data. It contains: - Sample type - ChannelMapping (implicitly identifies count of channels) - SampleRate - Layout

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[Boost.FixedPoint] Choose notation
by Dmitriy Gorbel 30 Apr '13

30 Apr '13

Hello, community! I propose extending the Boost Libraries to provide binary fixed-point arithmetic, within GSOC project. Fixed-point library will provide nonnegative and negatable class templates for fractional arithmetic, and cardinal and integral for integer arithmetic. In total, four class templates. Fixed-point arithmetic use more than one notation, and I want to provide several notation to make happy all. Now I plan to implement two notations - Q notation and notation from C++1y proposal. Examples: C++1y proposal notation: cardinal<16> 0 <= n < 65536 integral<4> -16 < n < 16 nonnegative<8,-4> 0 <= n < 256 in increments of 2^-4 = 1/16 negatable<16,-8> -65536 < n < 65536 in increments of 2^-8 = 1/256 Q notation: cardinal<16> 0 <= n < 65536 integral<4> -16 < n < 16 nonnegative<8, 4> 0 <= n < 256 has 4 bit for fractional part negatable<16, 8> -65536 < n < 65536 has 8 bit for fractional part Please, help me to choose default notation, propose other notation, or just make any feedback. Sincerely, Dmitriy. -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-FixedPoint-Choose-notation-tp46462… Sent from the Boost - Dev mailing list archive at Nabble.com.

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[GSoC 2013] Moving to Boost to Boost.Move
by Vicente J. Botet Escriba 30 Apr '13

30 Apr '13

Hi, In case there are some students that are looking for a last idea. There a re a lot of Boost libraries that don't support move semantics. It would be nice if one student propose to adapt the some of the existing libraries. The idea is to use Boost.Move so that an emulation is provided for compilers not supporting rvalue references. Some of the libraries (let me know if I'm wrong are). My priority is given between [], lower numbers means higher priority. Of course others would have others priorities: C++11 * [0] Tuple or * Fusion/tuple (it seems that it support or will support c++11 move semantics but don't use Boost.Move) * [0] Bind * [1] Function * [2] SmartPtr * [8] Array ? Accepted for C++14 * [5] optional Having an active proposal for C++1y * [3] Heaps * [6] Any * [7] Variant Other * [4] LockFree * [9] Parameters * [10] Signals? Please help me to complete this list. Adding constexpre and noexcept would be welcome also. Best, Vicente

3 4

Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 30 Apr '13

30 Apr '13

> > There are many ways systemically of implementing futures. The way you > > and Anthony have taken to date is a non-intrusive approach such that > > futures stand alone. This is great for not forcing design onto third > > parties and is a decentralised POSIX-y approach, but it comes with > > significant performance and memory costs because it's hard to get > > standalone, non-intrusive futures to batch themselves without > > sacrificing performance. > > I have no merit here. This is the approach the standard has defined futures. No major changes to the C++11 futures API is needed. Rather that a different, but compatible, optimized implementation of future<> gets returned when used from a central asynchronous dispatcher. So the C++ standard remains in force, only the underlying implementation is more optimal. > > An alternative approach is to assume a central dispatcher/event loop > > which can optimize then() chaining because it knows of all futures and > > their relationships currently in flight (this is a much more > > centralized statist NT-y approach, and it you can see that philosophy > > clearly in Microsoft's N3428). You can see an example of this approach > > to implementing future chaining with multiple dependencies which > > extends Boost.ASIO in > > https://github.com/ned14/TripleGit/blob/master/triplegit/include/async > > _file_ io.hpp#L785. I also went ahead and implemented N3428's > > when_all() which returns a future chained to multiple input futures, > > not that I claim the implementation mature yet. > > I don't know ASIO enough to understand the advantages or liabilities. > While a central dispatcher/event loop could be useful for some applications > other need more concurrency. > I'll need to take a deep look at ASIO when I would have enough time. I know you'll have studied Microsoft's N3428 in depth. Their proposal is quite trivial to implement when you have an NT kernel to hand where the kernel directly manages all multithreading primitives and there is a top quality APC implementation. Implementing N3428 without a NT kernel to hand is very considerably harder, indeed there are many, many gotchas as I know you know. Even then() is tricky, because code called from then() needs two main call forms, asynchronous and synchronous (i.e. the original object completes only after type B then() completes, whereas type A then() lets the original complete first). Not introducing race conditions is quite hard (for me at least). > > My concern with Boost.ThreadPool right now is that it could get in the > > way of the latter approach. I have zero objection to a formulation > > which embraces both approaches, but when you ask why a thread pool > > isn't in the standard, I think it's because until we've fixed futures > > implementation and all the composibility and chaining we're sure we > > need, and made sure that interops smoothly with the forthcoming TR2 > > networking proposal, then and only then is it wise to proceed with > > threadpool design. > > I'm not aware of the TR2 networking proposal needs respect to futures or > thread pool. Again I'll take a look to the current proposals. Futures come in because you'd naturally use std::packaged_task<> with Boost.ASIO. It returns a future. > > All that said, this is purely a cautious opinion of mine. You're one > > of the Boost.Thread maintainers, so I happily defer to your judgment > > on this. If you think we need a threadpool now, you'll find no > > opposition from me. > > If IIUC you are not suggesting that the student uses the ASIO approach, but that > it is not time to solve the thread_pool now. Could you confirm? > If yes, could you tell me what is blocking that we can not try to solve? We ought to finish N3428 for pure POSIX first. During implementation, you will find many areas where significant optimization using a central dispatcher become possible. Specialisations of N3428 for some arbitrary central dispatcher might be worth prototyping as a thought exercise. After that I see no reason to hesitate on thread_pool as it now has the type inferences available to it to have an optimal design. > I was not aware that there was a AFSIO GSoC project as described here > https://svn.boost.org/trac/boost/wiki/SoC2013#Boost.ASIO and that this > project propose also thread pool. I understand better now your concerns. I hadn't announced it to this list for various reasons. Hopefully I'll have news there soon. For reference, the AFSIO/AFIO project is *not* a threadpool. It's a batch asynchronous execution engine based on Boost.ASIO that lets you chain, in vast numbers, huge arrays of std::function<> whose returns are fetched using std::future<> to be executed asynchronously according to specified dependencies e.g. if A and B and C, then D, then E-G. That sort of thing. One thing presently implemented on that engine is asynchronous file i/o, but in the next month or two you'll hopefully see batch parallel SHA256 using 4-SHA256 SSE2 and NEON implementations also added to the asynchronous engine. The idea is that the engine is fairly generic for anywhere where you do need to chain lots of coroutine type items together (not that it supports Boost.Coroutine yet). v1 isn't particularly generic nor optimal, but I'm hoping with feedback from Boost that v2 in a few years' time would be much improved. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

3 2

[iterator] Is there general const_iterator adaptor?
by TONGARI 30 Apr '13

30 Apr '13

Hi folks, I wonder if there's a general const_iterator adaptor that transforms any iterator to a const one: template<class Iterator> struct const_iterator : iterator_adaptor < const_iterator<Iterator>, Iterator , typename iterator_value<Iterator>::type const > { const_iterator() {} const_iterator(Iterator const& base) : const_iterator::iterator_adaptor_(base) {} }; Which is simple but handy for use in that we don't have to make 2 versions for both const & non-const iterators each time we make a container. Does Boost offer this which I missed somewhere, or would you think it's a good idea to add? Thanks

3 5

GSOC 2013
by Razvan Florea 29 Apr '13

29 Apr '13

Hello, I'm a student interested in working on odeint project this summer in GSOC. In the last weeks I spoke with Mario Mulansky about my ideas. After he gave me a task in order to accustom with odeint project, I started building my proposal. He suggested me to put my first version of proposal on the mailing list to get feedback or some advice about what should I change. Is this the right mailing list to share my proposal? If yes, how should I share my proposal with you? Should I put on melange or can I put it on a google doc and give you a link to it? Have a nice day, Razvan

3 3

Re: [boost] hi
by dominic ibeme 29 Apr '13

29 Apr '13

http://expecthead.com/wp-content/plugins/wp-plugin-repo-stats/china.php?ygf… \\\\\\ The improver of knowledge absolutely refuses to acknowledge authority, as such. For him, skepticism is the highest of duties, blind faith the one unpardonable sin. -- Thomas Huxley (1866)

1 0

Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 29 Apr '13

29 Apr '13

> > I'm not ruling out the merit of a Boost.Thread threadpool. For me > > personally though, the hurdle is very significantly raised: you need > > to strongly prove to me why your proposed thread pool is much superior > > to a Boost.ASIO based threadpool. Otherwise I will zero score the GSoC > > proposal, because in the end we need other proposed projects more. > This is your right, but I don't know how the fact you can write easily the thread > pool you need to diminish a generic thread pool working well with futures. > [snip] > Hopping this helps you to understand the project I'm looking for. There are many ways systemically of implementing futures. The way you and Anthony have taken to date is a non-intrusive approach such that futures stand alone. This is great for not forcing design onto third parties and is a decentralised POSIX-y approach, but it comes with significant performance and memory costs because it's hard to get standalone, non-intrusive futures to batch themselves without sacrificing performance. An alternative approach is to assume a central dispatcher/event loop which can optimize then() chaining because it knows of all futures and their relationships currently in flight (this is a much more centralized statist NT-y approach, and it you can see that philosophy clearly in Microsoft's N3428). You can see an example of this approach to implementing future chaining with multiple dependencies which extends Boost.ASIO in https://github.com/ned14/TripleGit/blob/master/triplegit/include/async_file_ io.hpp#L785. I also went ahead and implemented N3428's when_all() which returns a future chained to multiple input futures, not that I claim the implementation mature yet. My concern with Boost.ThreadPool right now is that it could get in the way of the latter approach. I have zero objection to a formulation which embraces both approaches, but when you ask why a thread pool isn't in the standard, I think it's because until we've fixed futures implementation and all the composibility and chaining we're sure we need, and made sure that interops smoothly with the forthcoming TR2 networking proposal, then and only then is it wise to proceed with threadpool design. All that said, this is purely a cautious opinion of mine. You're one of the Boost.Thread maintainers, so I happily defer to your judgment on this. If you think we need a threadpool now, you'll find no opposition from me. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

3 2

[interprocess] [container] Can iterator hold raw-pointer instead of offset_ptr?
by TONGARI 29 Apr '13

29 Apr '13

Hi there, When putting containers in shared memory, offset_ptr is used internally, and IIUC, the iterator of the container will also use offset_ptr. But it seems to me that in most cases we only use iterator locally rather than putting those iterators in shared memory as well, so the plain-old-raw-pointer is sufficient and hopefully more efficient for iterator's usage. What do you think?

3 4

[gsoc 2013] Approximate string matching
by Jan Strnad 29 Apr '13

29 Apr '13

Hi, I'm Jan Strnad, currently a Master's student at CTU in Prague, Czech Republic. This summer, I would like to participate in GSOC and I believe that approximate string matching is a good match for me, since my background i this area is quite strong. Now more specifically. I would like to implement approximate string matching algorithm(s) based on the NFA. I would like to support various approximate distances, such as Hamming distance [1], Levenstein distance [2], Damerau-Levenstein distance [3], Delta distance, Gamma distance and finally (delta, gamma) distance. Sorry no explanation of the last three found on the Web, but I can provide one if interested. In the matter of NFA implementation, I would probably choose dynamic programming approach, but I'm thinking of shift-or algorithm as well. Can I ask you for any kind of thoughts or feedback regarding this topic? Best regards, Jan Strnad [1] http://en.wikipedia.org/wiki/Hamming_distance [2] http://en.wikipedia.org/wiki/Levenstein_distance [3] http://en.wikipedia.org/wiki/Damerau%E2%80%93Levenshtein_distance

7 19

[Property Map] put_get_helper, keys are passed by value
by ilker 29 Apr '13

29 Apr '13

Hello, I require a pm which returns passed key (itself or a 'part' of it) as mapped value. For this purpose I wrote another helper since boost::put_get_helper's put function passes keys by value. // Pasted as a reminder template <class PropertyMap, class Reference, class K, class V> inline void put(const put_get_helper<Reference, PropertyMap>& pa, K k, const V& v) { static_cast<const PropertyMap&>(pa)[k] = v; } Is there any way to accomplish this by not introducing another custom helper ? (may be there already something similar exists in boost) Thanks. -- View this message in context: http://boost.2283326.n4.nabble.com/Property-Map-put-get-helper-keys-are-pas… Sent from the Boost - Dev mailing list archive at Nabble.com.

1 0

[operators] What is the correct overload set for a binary operator?
by Daniel Frey 28 Apr '13

28 Apr '13

Hi, after some more experiments, I convinced myself that I should explore the option of returning an rvalue (not an rvalue reference) in all cases when implementing operator+ based on operator+= (as an example). But I wonder what the most efficient overload set would look like. With this post I'll concentrate on same-type operations (T+T). Given a class T with operator+= like this: T& T::operator+=( const T& ); T& T::operator+=( T&& ); // if useful the class provides it and it should be used if applicable I think the following is currently the best overload set for operators: T operator+( T lhs, const T& rhs ) { lhs += rhs; return lhs; // no std::move needed } T operator+( T&& lhs, T&& rhs ) { lhs += std::move( rhs ); return std::move( lhs ); } T operator+( const T& lhs, T&& rhs ) { #ifdef COMMUTATIVE rhs += lhs; return std::move( rhs ); #else T nrv( lhs ); nrv += std::move( rhs ); return nrv; #endif } I tested this with the following expressions with both COMMUTATIVE defined and not defined: T a, b, c; // initialized to something T r1 = a + b + c; T r2 = a + ( b + c ); T r3 = ( a + b ) + ( b + c ); and with both GCC 4.7.3 and Clang 3.2. Could someone please test this with VC++? (complete code below) Generally: Any thoughts? Examples of expressions where and how it could be improved? Theoretical improvements are also welcome, but please mark them as such and always test your code to prevent pessimizations in practice! One remarks about the proposed full version of operators2.hpp: Andrew, I really appreciate your work and enthusiasm, but please understand that IMHO this needs to be done step-by-step and much more slowly than you probably hope for. Let's figure out the proper overload set for T+T first, then T+U/U+T (again both commutative and non-commutative), noexpect-specifier for all overloads, etc. After that, we need to decide on whether or not to improve the existing operator library or to provide an independent V2. This might include rethinking the grouped templates. Using Boost.Move might help with the implementation or not, depending on what overload set we want/need. It all needs tests and documentation and it will be quite some work… hope you and others are still with me on this :) Best regards, Daniel Here's the complete test code I used: #include <iostream> #include <utility> struct MyClass { MyClass() { std::cout << "MyClass::MyClass()" << std::endl; } MyClass( const MyClass& ) { std::cout << "MyClass::MyClass( const MyClass& ) COPY" << std::endl; } MyClass( MyClass&& ) { std::cout << "MyClass::MyClass( MyClass&& ) move" << std::endl; } ~MyClass() { std::cout << "MyClass::~MyClass()" << std::endl; } MyClass& operator+=( const MyClass& ) { std::cout << "MyClass::operator+=( const MyClass& ) +=" << std::endl; return *this; } MyClass& operator+=( MyClass&& ) { std::cout << "MyClass::operator+=( MyClass&& ) += &&" << std::endl; return *this; } }; MyClass operator+( MyClass lhs, const MyClass& rhs ) { lhs += rhs; return lhs; } MyClass operator+( MyClass&& lhs, MyClass&& rhs ) { lhs += std::move( rhs ); return std::move( lhs ); } // #define COMMUTATIVE MyClass operator+( const MyClass& lhs, MyClass&& rhs ) { #ifdef COMMUTATIVE rhs += lhs; return std::move( rhs ); #else MyClass nrv( lhs ); nrv += std::move( rhs ); return nrv; #endif } int main() { MyClass a, b, c; std::cout << "--- r1" << std::endl; MyClass r1 = a + b + c; std::cout << "--- r2" << std::endl; MyClass r2 = a + ( b + c ); std::cout << "--- r3" << std::endl; MyClass r3 = ( a + b ) + ( b + c ); std::cout << "--- done" << std::endl; }

3 8

GSOC 2013
by Dmitriy 28 Apr '13

28 Apr '13

Hi folks! I am Dmitriy Gorbel, a computer science student at the Kharkiv Polytechnic University from Ukraine. I browsed Boost C++ Libraries home page for GSoC and I want to propose a project to implement of a Fixed Point library. I read open standard on open-std.org http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3352.html and tried implementation by Vicente J. Botet Escriba at the https://svn.boost.org/svn/boost/sandbox/fixed_point/ Now I prepare my proposal. So I will take implementation by Vicente J. Botet Escriba in the first place, and I found few more simple implementations, but can anyone advise me other implementations of Fixed Point arithmetic, which I must pay attention? Not necessarily in C++, pure C also would be good. Thanks

5 29

Re: [boost] [GSOC] XML library of Boost
by Amos Ji 28 Apr '13

28 Apr '13

On Apr 28, 2013, at 12:11 PM, Andrey Semashev <andrey.semashev(a)gmail.com> wrote: > On Monday 29 April 2013 02:08:01 Amos Ji wrote: >> Hi All, >> >> I'm a graduate student from Fudan University in China. And I hope to >> contribute some code to Boost during the GSOC. >> >> I've scanned the idea page. The ideas in the page are all very interesting >> and challenging. But what I'm interested in most is XML library, which is >> at the bottom of page. I think the XML format is the most popular standard >> for storing information so it's important for Boost to have a good XML >> library. > > Agreed, a good and fast XML library would be most useful. >> In my opinion, an XML parser must be able to do these things: >> >> 1. To Iterate over DOM nodes tree; >> 2. To access the values of nodes and their attributes quickly; >> 3. To insert or delete nodes or attribute of an exact node easily; >> 4. To generate new XML from the structure which stores XML in the >> library. > > IMHO, support for SAX is also mandatory. I would even say that SAX should be > the first and the primary thing to be implemented in Boost.XML, as DOM can be > added later on top of it if the time for GSOC allows. > I agree. SAX parser will use less memory than DOM parser. I'll add it into my proposal. > You also listed support for encodings in the optional features. I agree with > it being optional with exception for Unicode. At least UTF-8 should be > supported from the very start. But that should not be a problem now that we > have Boost.Locale. I know little about Boost.Locale. I'll see how it can help support other encodings when I need. Thanks a lot for your suggestions. _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

1 0

Google Summer of Code 2013
by sskytyba＠gmail.com 28 Apr '13

28 Apr '13

I’m student from Ukraine. My name is Skytyba Sergij. I want to get some information. I’m interested in such projects as Boost.uBLAS, Boost.Math Bernoulli Numbers and Applications to Special Functions (very) , Boost.Multiprecision (very) , Boost.Thread/SyncQueue, Moving Boost to Boost.Move. To whom can I send my proposal and how can I contact with mentors of these projects?

2 1

[GSoC] Boost.Multiprecision project
by Віталій Мельник 28 Apr '13

28 Apr '13

Hi! I am a second year student in Computer Science and I`m very interested in Boost.Multiprecision project on GSoC. What can I do to be invited to this project? I have some achievements in sport programming, so I can tell you that I know algorithms and I like to solve algorithmic problems. -- Vitalii Melnyk

2 1

Re: [boost] GSoC Boost.Multiprecision project
by Jyotesh Choudhari 28 Apr '13

28 Apr '13

> 2013/4/21 Jyotesh Choudhari <jyoteshrc_at_[hidden]>: > <...> >> Looking at the project description, I think I have understood what needs to >> be implemented in this project. I have also gone through the current code >> cpp_bin_float.hpp and I have understood some part of it. I want to know how >> detailed should my proposal be? What details should I include in my >> proposal? What should be the deliverables for the project? > Hi, and welcome! > Start from writing a proposal according to this link > https://svn.boost.org/trac/boost/wiki/SoCSubmissionTemplate<https://svn.boost.org/trac/boost/wiki/SoCSubmissionTemplate>. > This link may also help https://svn.boost.org/trac/boost/wiki/SoCHints I have attached my proposal with this mail. Please have a look at it and let me know your feedback. Thanks and regards, Jyotesh Choudhari > After it is done, mail it ti this mailing list with title starting > from [boost] GSOC. > I also recommend to read this mailing list first, because there is a > lot of interesting discussions and useful information about GSOC and > some comments about Boost.Multiprecision. > One more advice: there are already two or three students that want to > work on Boost.Multiprecision. Try to describe in your proposal why do > you suit for that task better than others. > -- > Best regards, > Antony Polukhin

2 1

[GSOC-2013]-boost.odeint implicit routines
by preethamsreenivas 28 Apr '13

28 Apr '13

Hi all, I am preetham sreenivas, a sophomore at computer science and engineering, IIT Bombay(Indian Institute of Technology, Bombay). I am very much interested in the project of adding support to implicit routines to the boost.odeint library. I have recently completed a course on numerical analysis and i've used all the common numerical methods as part of the course including euler methods , runge-kutta routines etc. I've also used the boost.odeint for algorithmic analysis assignments for this course. I've gone through the articles linked from the project description and also snippets of odeint code at codeproject.com I would like to get through to mario mulansky or Karsten Ahnert , the mentors for this project to provide me with further pointers and any assignments they would like to give me. I am sorry that i couldn't start on it earlier as i've just completed my exams for the spring semester. please reply as soon as possible. kindly oblige, regards, preetham sreenivas, sophomore, CSE IIT Bombay -- View this message in context: http://boost.2283326.n4.nabble.com/GSOC-2013-boost-odeint-implicit-routines… Sent from the Boost - Dev mailing list archive at Nabble.com.

2 1

GSoC uBLAS algorithms for derterminants, inversion and decomposition
by Ganesh Prasad 28 Apr '13

28 Apr '13

As inversion involves steps that use the determinant of the matrix, it's better to develop an algorithm that evaluates the determinant of the matrix faster than the conventional recursive way. I think extending the rule of Sarrus does the trick. So far we have used rule of sarrus as a light weight formula for evaluating determinants of 2x2 and 3x3 matrices. But extending it in the following way makes it applicable for higher order matrices too. And this algorithm has a time complexity O(2*n^2) for nxn matrices. // a is a n x n matrix Det_a=0 Sum1=0 Sum2=0 For count=0 to n-1 do For i=1 to n do J=i+count Val=(j>n)?n:0 j-=val product*=a[i][j] sum1+=product For count=0 to n-1 do For i=1 to n do J=n-count-(i+1) Val=(j<1)?n:0 J+=val product*=a[i][j] sum2+=product det_a=sum1-sum2 return det_a I want to use this algorithm in my GSoC project to evaluate determinants, and based on this implementation I'll develop algorithms for inversion and decomposition. But I think if we can make some changes to this algorithm, this may run faster. As you can see, this thing traverses the matrix twice. If we can achieve the goal in only one traversal calculating sum1 and sum2 simultaneously, then it'd be a bit faster, but here I lack ideas. So please provide me with some help in this regard. ~Ganesh Prasad

1 0

[Boost][GSOC] proposal for Trie
by Hardy Huang 28 Apr '13

28 Apr '13

Hi, this is my proposal for GSOC 2013, please read it and give me some useful information on it, thanks == Personal Details == * Name: Zhe(Hardy) Huang * College/University: Peking University * Course/Major: Computer Science * Degree Program: M.Sc. * Email: hzithlony(a)gmail.com * Homepage: not yet * Availability: * How much time do you plan to spend on your GSoC? I will spend the most part time of the semester(till late June), and then the whole summer on my GSoC project. * What are your intended start and end dates? I basically will obey the rules of GSoC, and I will also listen to mentor’s advice on it. * What other factors affect your availability (exams, courses, moving, work, etc.)? I am having my courses now, and I will have my final exams in June. Since I am not having many courses, I have enough time to do something for the project before exams. And in summer I could almost work full time on it. == Background Information == Please summarize your educational background (degrees earned, courses taken, etc.). I majored in Computer Science in Zhongshan University from 2008 to 2012, by which I earned my bachelor’s degree. During the four years, I learned many basic courses on Computer Science, like algebra, logic, data structure, algorithms, operating system, Compilers, databases, networks. >From 2012 till now, I am studying Computer Science in Peking University pursuing my master’s degree. My research field is information retrieval. Please summarize your programming background (OSS projects, internships, jobs, etc.). GSoC is the first time that I get involved with a real and large OSS project. Besides, I’ve developed many things in C and C++. I developed a simplified B-tree data structure in C during my intership for a small company. Later a system in C to extract and evaluate the content of webpages for my research, and I am still on it. An implementation of a search system in C++. A webpage template system in C for my lab to generating webpages in order to do some research on them. Please tell us a little about your programming interests. I like to write codes for the basic and general use. I am pursuing well-framework of design and code, and high reusability when I think of develop the project. Please tell us why you are interested in contributing to the Boost C++ Libraries. Boost is widely used by programmers and famous for its powerful and efficient. It is an honor to contribute to such a lib, and have my codes used and reviewed by so many programmers. I like the reusability of well-designed lib, so it also will be a good chance for me to improve my skill of design and programming. And a good chance to communicate with good guys as well. I want to be a good programmer with many good programmers as my friends. What is your interest in the project you are proposing? Because I have participated in many competitions of algorithm, I have a good knowledge of algorithms and data structures. I have also implement many, but for the sake of winning, the codes usually can not be well-reused. Meanwhile the STL in C++, which I’ve used many times during the competitions, such as set, map, priority_queue, sort are good examples of well-reused algorithms and data structures. So I’ve been expecting to develop some general libraries of algorithms and data structures. Boost is a well-formed organization, and Boost lib is a widely-used lib, so I also want to learn some skills to develop a good lib from developing the project with mentors in Boost. Have you done any previous work in this area before or on similar projects? I am good at data structure and algorithm, and I wrote codes of various algorithms and data structures for many times. I am very familiar with the Trie data structure, and as I list above, I've develop a simplified general B-tree data structure in C, which is a good experience when I develop Trie for Boost. What are your plans beyond this Summer of Code time frame for your proposed work?. I will dedicate my summer to my work. And taking the experience as a good beginning, I will be feeling happy to contribute more to Boost, and other OSS projects. Please rate, from 0 to 5 (0 being no experience, 5 being expert), your knowledge of the following languages, technologies, or tools: - C++ 3 - C++ Standard Library 3 - Boost C++ Libraries 2 - Subversion 3 What software development environments are you most familiar with (Visual Studio, Eclipse, KDevelop, etc.)? I use Visual Studio in my lab, and vim + gcc for myself. What software documentation tool are you most familiar with (Doxygen, !DocBook, Quickbook, etc.)? I’ve used Doxygen before, it is simple and efficient. == Project Proposal == Please provide a description of your proposed work. Trie(Radix Tree) is an efficient in memory data structure to deal with string storing and searching. It can be used in many applications, and in comparison to hashtables, it has better expandability and stability. It will be an data structure of great importance and wide usage. == Proposed Milestones and Schedule == Please provide estimated milestones and schedule for completing the proposed work. Before May 27: To familiarize with the Boost lib, with reading the codes and discussing about it in mailing list. To have a better knowledge of lib, with reading some books of STL and Boost, and comparing Boost with STL. To setup us a proper environment for development. Study deep into Trie, reading some others’ good implementations. May 27 – June 17: Keep in touch with the Boost organization and have good communications with my mentor. Get involved with the development of boost. Try some toys about Boost, and discuss them with mentor, in order to know better about mentor and how the development goes on. June 17 – July 15(Coding period begins): Discuss the detail of the design with mento, develop an alpha version of Trie, and have it tested in small scale. July 15 – July 29(To mid-term evaluation): Refine my alpha codes, analyze the performance, and try to improve it. Write an initial report of the project and document of Trie. July 29 – September 23: Refine my codes, and have some thorough tests on it, make it robust. Reorganize codes and improve documents.

5 27

[result_of] Allow result_of to work with C++11 lambdas
by Nathan Crookston 27 Apr '13

27 Apr '13

Hi all, Using C++11 lambda functions with several boost components. For example, the following code snippet will not work with VC10, nor with g++ up to 4.8: #include <boost/assign.hpp> #include <boost/range/adaptors.hpp> #include <boost/range/algorithm.hpp> #include <iostream> int main() { std::vector<int> v; for(int i = 0; i < 10; ++i) v.push_back(i); boost::for_each(v | boost::adaptors::transformed([](int i) { return i * 2; }), [](int i) { std::cout << i << std::endl; }); } g++4.5 gives around 34k of error messages, while VC10 has a mere 22k. The root of these problems is that lambda functions don't conform to the tr1::result_of protocol -- there is no nested result_type member, nor nested result struct. The standard doesn't mandate this case since decltype may be used to deduce the return type on C++11-conforming compilers. boost::result_of disables the use of decltype on many compilers in favor of tr1-style deduction due to weaknesses in the implementation of decltype. While it is important to use tr1-protocol result_of to allow code involving incomplete types to compile, it would be very convenient to fall back to a decltype approach when it's detected that the tr1 protocol is not being followed. Jeff Hellrung suggested[1] a fallback to decltype *only* for compilers which had nonconforming decltype operators. Thus the only behavioral change would be that some code which before would produce an error would now compile and run correctly. A ticket[1] with a patch (including tests and docs) was created. Daniel Walker suggested further discussion on the list, which this attempts to provoke. I think this would be a nice improvement for a set of often-used compilers -- the list of boost-users questions whose problems could be addressed by this patch is extensive (and can be provided, if desired). Thanks, Nate [1] http://boost.2283326.n4.nabble.com/Range-amp-c-0x-Lambdas-Can-this-be-done-…<http://boost.2283326.n4.nabble.com/Range-amp-c-0x-Lambdas-Can-this-be-done-…> [2] https://svn.boost.org/trac/boost/ticket/7753

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[type_erasure] Using any with iterator Concept.
by Adam Wulkiewicz 27 Apr '13

27 Apr '13

Hi, I'm trying to use type-erased iterator in STL algorithms, e.g. copy but get errors like this one: error C2039: 'iterator_category' : is not a member of 'boost::type_erasure::any<Concept>' c:\program files (x86)\microsoft visual studio 10.0\vc\include\xutility 373 of course any doesn't define iterator_category. I'm using MSVC2010 and doing something like this: typedef boost::type_erasure::any< boost::type_erasure::iterator< boost::single_pass_traversal_tag > > iterator; // ... iterator first = return_some_iterator(...); iterator last = return_some_iterator(...); // BAM! std::copy(first, last, std::back_inserter(result)); // BAM! typedef iterator::iterator_category C; I simply tried to add it to the iterator<> Concept defined in iterator.hpp but this didn't help: template<...> struct iterator< ::boost::single_pass_traversal_tag, ...> : iterator< ::boost::incrementable_traversal_tag, ...> { typedef ValueType value_type; typedef typename iterator_reference< Reference, ValueType >::type reference; typedef DifferenceType difference_type; typedef std::input_iterator_tag iterator_category; }; Am I doing something wrong or is it an error in Boost.TypeErasure? Regards, Adam Wulkiewicz

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Bernoulli Numbers Implementation With More Precision and Boost.Test
by Gaurav Deshmukh 27 Apr '13

27 Apr '13

I have further improved the implementation of 'bernoulli' function for Math.Bernoulli project idea of GSoC-2013. In my previous update, I made the return type generic. But, there was lack of precision as I had mentioned. For achieving greater accuracy, I implemented the Akiyama-Tanigawa algorithm using 'cpp_rational' data type. As there is no approximation in intermediate steps, it gives best accuracy. It can be casted to the data types of 'cpp_dec_float'. But, I think this implementation may be slower than the previous implementations. So, there is trade-off between running time and precision. We may implement 'bernoulli' function in two ways. If priority is running time than the accuracy of precision, then we can use previous implementation. If priority is the precision, then we can use this implementation. I have attached the 3 files. 1) bernoulli.hpp : It contains the function fr calculating bernoulli number. 2) example.cpp : It contains the program to test bernoulli.hpp 3) test.cpp : This is the Boost.Test comparing the values calculated by benoulli.hpp with some of the published values.

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[gsoc 2013] Approximate string matching proposal
by Jan Strnad 27 Apr '13

27 Apr '13

Hi, I've already posted this but it probably got buried. My proposal for GSOC 2013 is also available at http://webdev.fit.cvut.cz/~strnaj11/gsoc/. Regards, Jan Strnad GSOC 2013 Proposal - Approximate string pattern matching ======================================================== Abstract -------- My name is Jan Strnad and this is my proposal for GSOC 2013. I would like to implement a set of approximate string matching algorithms. There are two categories of these algorithms. A representative of the first category takes two strings and computes so-called distance between those two strings. A member of the second category takes some text and a pattern and finds all approximate matches of the pattern in the text according to some given distance. I'm planning to support various distances, such as Hamming, Levenstein, Damerau–Levenshtein, Jaro, Delta, Gamma ... I'm proposing to implement a general solution that supports multiple string containers, not only std::string. There are many possible applications such as spell checking. Personal Details ---------------- Name: Jan Strnad University: Czech Technical University in Prague, Faculty of Information Technology, The Czech Republic Major: Theoretical Informatics / System Programming - studying both in parallel Degree program: MSc. Email/XMPP: hanny.strnad(a)gmail.com ICQ: 335127474 homepage: none Mailing address: Okružní 508, 788 13 Vikýřovice, Czech Republic Availability: * Start: at worse by 17th June but probably earlier * End: 21st September * I have no other duties during this period but I may take a one week vacation. * I'm planning to spend 40-45 hours per week. Background ---------- Please summarize your educational background I'm first year master's student at CTU in Prague with major in Theoretical Informatics and System Programming. At this university I also gained my BSc. degree (Software Engineering, with honors) in June 2012. Here's an incomplete list of courses I have taken so far: Data structures and algorithms, Graph theory, Complexity theory, Automata and grammar theory, Compiler design course, Software engineering courses (including practical ones), various programming languages (C, C++, Java, Scala, Common Lisp, Haskell, Erlang, SML), various programming paradigms (imperative, object-oriented, functional, logical), math & statistics courses, Data compression, String pattern matching course, Computer architecture related courses, Parallel algorithms course and many others. I also spent 4 months as an exchange student in Uppsala University, Sweden where I took Constraint programming and Software verification courses. Please summarize your programming background I'm able to code in many languages, but I'm most experienced in C++ (5 years) and Scala languages (1.5 years). My C++ experience is gained mostly from school's projects an my small own projects (usually some kind of small tweaks of third party programs). I have an experience with C++ templates, multi-threading using both POSIX threads and openMP, STL and with some of the Boost libraries (Program Options, Smart Ptr). I definitely not know everything that would be needed for my GSOC project, but I'm quick learner. Please tell us a little about your programming interests. Please tell us why you are interested in contributing to the Boost C++ Libraries. What is your interest in the project you are proposing? As you may have guested, my professional interests are programming languages (especially their paradigms), concurrent & parallel programming and finally everything related to theoretical informatics. That includes things such as data compression or pattern matching. This is also one of the reasons why I want to contribute to Boost. I want to share my knowledge of pattern matching algorithms and I believe that the Boost project is the right place. I'm seeking for an off the school programming experience. Another reason is that since I'm a long time user of various open source software, I believe that it is time to start to contribute to community as well. From this program I mostly expecting gaining some real world experience. My C++ and especially Boost knowledge should improve significantly. Have you done any previous work in this area before or on similar projects? I think I have everything that is needed to successfully complete this project. I have a theoretical foundations of approximate string matching algorithms from my university courses as well as I'm able to implement them using C++ without any major issues. What are your plans beyond this Summer of Code time frame for your proposed work?. I know that it may take a long time for a project to become a part of Boost library. So, if selected, my intentions after the summer is over are: 1. Release my project as an open-source, not necessary as a standard part of Boost library. 2. Do everything necessary to include my work as a part of standard part of Boost library eventually. 3. Further development: adding support of more distances, implementing another string algorithms such as repetitions searching. This heavily depends on users' interest. I know that my work won't end by the end of summer. I'm willing to spend a couple of hours per week (say 2 or 3) to keep my project updated and most importantly alive. Languages, technologies, tools My regular C++ development environment is consisted of Linux, git, CMake, Sublime text, gdb and valgrind. I have also used Eclipse and svn before. For documentation purposes I'm most familiar with Doxygen. Here is a self-evaluation of desired skills: C++ 3 STL 4 Boost libraries 1 Subversion 3 Proposal -------- Approximate string matching is used in many areas. To name some of them, there are spell checking and DNA processing. I can also imagine many applications in human-to-computer interaction. I'm proposing an extension of Boost String algorithms library. I would like to implement algorithms of two categories: 1. Compute distance of two strings. Imagine a function that takes two strings a returns a number describing their distance (various distances are described below). 2. Find all approximate matches of a pattern in some text using given distance. Example of this can be found in API interface usage example. Distance is defined as a number (or a tuple of numbers) describing similarity of two strings. Here is a list of all distances I'm planning to implement: 1. Hamming - a number of replace (single character only) operations needed so that the strings match exactly. 2. Levenstein - a number of insert, delete and replace operations. 3. Generalized Levenstein (Weighted Levenstein) - same as before but each operation may have different cost. 4. Damerau-Levenstein - a number of insert, delete, replace and transpose (of two adjacent characters) operations. 5. Weigted Damerau-Levenstein - same as before but each operation may have different cost. 6. Jaro - please see [1] 7. Jaro-Winkler - also see [1] (following assumes we can compute distance of two characters, eg. c - a = 2) 8. Delta - the maximum number of distance between two characters, eg. Delta(aaa,bbb) = Delta(aaa,aab) = 1. 9. Gamma - a cumulative distance between two characters, Gamma(aaa,bbb) = 3. 10. (Delta, Gamma) - a combination of two preceding distances. Distance 10 is not exactly needed, but I included it because it is quite common to compute both Delta and Gamma distances at the same time, so I provided efficient algorithm for this. As noted, when using distances 8-10 we must be able to compute distance between two characters. This behavior should be customizable as well. Simple API definition follows. It's very immature and it will change but it should give you general idea: ~~~~ {.cpp} namespace boost{ template <typename TRange> std::size_t hamming_dist(TRange first, TRange second); template <typename TRange> std::size_t levenstein_dist(TRange first, TRange second); template <typename TRange, typename Type> Type weighted_levenstein_dist(TRange first, TRange second, Type replace_cost, Type insert_cost, Type delete_cost); template <typename TRange> std::size_t damerau_levenstein_dist(TRange first, TRange second); template <typename TRange, typename Type> Type weighted_damerau_levenstein_dist(TRange first, TRange second, Type replace_cost, Type insert_cost, Type delete_cost, Type transpose_cost); template <typename TRange> std::size_t delta_dist(TRange first, TRange second); template <typename TRange> std::size_t gamma_dist(TRange first, TRange second); template <typename TRange> float jaro_dist(TRange first, TRange second); template <typename TRange> float jaro_winkler_dist(TRange first, TRange second, float weight); template <typename TRange> std::pair<std::size_t, std::size_t> deltagamma_dist(TRange first, TRange second); template <typename Type> class approximate_distance { // ... }; class hamming_distance : public approximate_distance<std::size_t>{}; template <typename Type, typename TRange> class approx_pattern { public: approx_pattern(approximate_distance<Type>& distance, Type max_allowed, TRange pattern); }; template <typename Type, typename TRange> class sapprox_match_iterator { public: sapprox_match_iterator(TRange text, approx_pattern<Type, TRange>); // overloaded ++ and * operators }; template <typename Type, typename TRange> class sapprox_match_result { public: Type distance() const; std::size_t startIndex() const; std::size_t endIndex() const; TRange str() const; }; } ~~~~ Here is an example of usage: ~~~~ {.cpp} string a = "aaabc"; string b = "aaacb"; cout << boost::hamming_dist(a, b) << endl; // prints 2 cout << boost::damerau_levenstein_dist(a, b) << endl; // prints 1 string pattern = "acbdef"; string text = "aacdefbcdefabccef"; boost::approx_pattern ap(boost::hamming_distance, 1, pattern ); boost::sapprox_match_iterator begin( text, ap ); boost::sapprox_match_iterator end; std::for_each( begin, end, []( const boost::sapprox_match_result& what ) { cout << what.str() << " starting at " << what.startIndex() << endl; } ); // aacdef at 0 , fbcdef at 5, abccef at 11 ~~~~ As you can see, I would like my implementation to be general so that other string containers can be used instead of std::string. A will also take care of proper design in a way that further distances can be easily added later. There are multiple implementation approaches that can be used: NFA simulation, Shift-or algorithm and dynamic programming approach. I will probably choose the dynamic programming - it has low time and space complexity as well as it does not require any kind of preprocessing. Thus searching all occurrences of pattern in a text has O(m*n) complexity, m is length of pattern, n is length of text. Related work There is currently only one C++ library I know of: Flamingo [2]. From my point of view, its usage is a kind of complicated. You can also find implementations of single functions on-line, but they lack of multiple distances support as well as they are not general (eg. designed for C-like strings only). Another related project is stringmetrics [3]. This project is written in Scala so it is not related to C++ programmers. Schedule -------- This is an approximate schedule I would like to keep on. Since I will probably hit many unexpected issues I have reserved some time for it. 17th June : start 17th June - 27th June : prototyping and designing API interface as well as auxiliary functions / classes 28th June - 30th June : setting up testing environment, writing basic unit tests 1st July - 14th July : implementation of general dynamic programming model that will be used by most distances 15th July - 28th July : implementation of distances 1 - 5 29th July - 4th August : implementation of distances 8 - 10 5th August - 11th August : implementation of distances 6,7 12th August - 1st September : implementation of approximate pattern search in a text for all distances 2nd September - 15th September : wrapping up, end user documentation 16th September - 21st September : reserved During all implementation phases I'll be also performing testing and source code documentation. References ---------- [1] http://en.wikipedia.org/wiki/Jaro-Winkler_distance [2] http://flamingo.ics.uci.edu/releases/4.1/ [3] http://rockymadden.com/stringmetric/

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[gsoc 2013] chrono::date
by Anurag Kalia 27 Apr '13

27 Apr '13

After going through related docs and general information, I have some questions regarding the chrono::date library. What is the origin of the name 'chrono'? I have assumed till now, it has something to do with chronology, but I am not sure.Why is date a part of 'chrono' at all? As I understand, chrono::date library is supposed to be based on the counts of sunrises. I am in favour of it because it elegantly circumvents the complications of leap seconds which are unnecessary with date-related arithmetic. But if we want it to be compatible with the rest of chrono library, complications arise:If we use a definition in line with principles of chrono (i.e. not using sunrises for a moment), a date really becomes a time-interval defined by the 00:00:00 of that date + a duration of 1 day, if we follow the rules of chrono library. But the length of a day can be changed today due to insertion/deletion of leap seconds to the conventional 24-hour day, if needed. Moreover, this change is arbitrary, since leap seconds are used to keep the time in sync with earth's rotations, which changes without a fixed pattern.The length of month and year similarly are complicated, not only by the length of days in it (see above) but also by the variable number of days. For example January has 31 days, April has 30 days and February has 28 or 29 days depending upon common year or leap year respectively. Due to the latter, length of year also varies between 365 and 366 days.In essence, there is no fixed duration of day, month or year; unlike the rest of chrono library which fundamentally is based on 'duration' class.Now if we revert to our original definition, our library basically becomes a count of sunrises since epoch. Aren't we forming an independent library from chrono then?What does one mean when one says the chrono::date library interoperates with rest of chrono library? This question is an offshoot of previous question. I am confused as to how far can both parts interoperate given the above-mentioned complications. Subtraction of dates yields us theoretically a duration of a number of days. But since actual time duration of a day is ill-defined (see above), we have to return the answer in resolution of seconds, if we use 'duration' at all. I am unable to think of more possibilities of cross-pollination between the two parts. Am I correct in my reasoning? I am genuinely stuck at this clubbing up of unrelated (to me) classes. Even more so because Boost already supplies such a vast number of header files with least number of interdependencies. A smaller self-contained date library seems (to me) more in line with its principles. Thanks,Anurag Kalia.

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 27 Apr '13

27 Apr '13

> > [1] http://danlincan.3owl.com/gsoc/Proposal.pdf > > > I have some questions: > > * Why the submit function of all the thread pools doesn't returns the same? > * What is the advantage of returning future from submit call? > .... My personal big issue with a Boost.Thread threadpool is why adding one is necessary when forty lines of C++11 code using Boost.ASIO implements you one: /*! \class thread_pool \brief A very simple thread pool based on Boost.ASIO and std::thread */ class thread_pool { class worker { thread_pool *pool; public: explicit worker(thread_pool *p) : pool(p) { } void operator()() { pool->service.run(); } }; friend class worker; std::vector< std::unique_ptr<thread> > workers; boost::asio::io_service service; boost::asio::io_service::work working; public: //! Constructs a thread pool of \em no workers explicit thread_pool(size_t no) : working(service) { workers.reserve(no); for(size_t n=0; n<no; n++) workers.push_back(std::unique_ptr<thread>(new thread(worker(this)))); } ~thread_pool() { service.stop(); for(auto &i : workers) i->join(); } //! Returns the underlying io_service boost::asio::io_service &io_service() { return service; } //! Sends some callable entity to the thread pool for execution template<class F> future<typename std::result_of<F()>::type> enqueue(F f) { typedef typename std::result_of<F()>::type R; // Somewhat annoyingly, io_service.post() needs its parameter to be copy constructible, // and packaged_task is only move constructible, so ... auto task=std::make_shared<boost::packaged_task<R>>(std::move(f)); // NOTE to self later: this ought to go to std::packaged_task<R()> service.post(std::bind([](std::shared_ptr<boost::packaged_task<R>> t) { (*t)(); }, task)); return task->get_future(); } }; ... and you're done. Moreover, this thread pool integrates seamlessly with Boost.ASIO ioservice callback dispatch which is a huge plus. I took that example from some page on the internet, so I don't claim I wrote most of the above. Do bear in mind before you respond that parts of Boost.ASIO are scheduled to enter the standard in TR2, therefore no you won't need Boost.ASIO as a dependency soon. I'm not ruling out the merit of a Boost.Thread threadpool. For me personally though, the hurdle is very significantly raised: you need to strongly prove to me why your proposed thread pool is much superior to a Boost.ASIO based threadpool. Otherwise I will zero score the GSoC proposal, because in the end we need other proposed projects more. By the way, I actually don't object at all if your proposed Boost.Thread threadpool is a thin wrapper of Boost.ASIO. That, actually, is just fine with me, though I'd doubt Google would feel it substantial enough for GSoC funding seeing as it would be finished within a week. Niall

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[operators] v2 test code
by Andrew Ho 26 Apr '13

26 Apr '13

I took a some time re-working the operators header based on previous feedback provided. Hopefully this will allow us to get a rough base worked out and we can work through some of the details. Most of the general idea is the same as v1, but there are a few changes and in general is not backwards-compatible. As far as I know this should be usable and support at least all of the features provided by v1 or something equivalent (see notes). codepad link: http://codepad.org/F2LrIUD2 notes: 1. Rather than using op1/op2, this version uses template specialization to make the distinction between the two. 2. All math operators have commutative and non-commutative versions, as well as left versions. Distinction is made by struct name, i.e. op is non- commutative, op_commutative is commutative, and op_left is the left variation. Note that there isn't any hard checks to prevent op_left<T, T> (which obviously makes no sense, may even result in a compiler error regardless), but the internal composite operators all use template partial specialization which don't have op_left if U = T. 3. I opted for the return-by-value only method to safely handle move semantics (see other discussion Daniel started for why). Changing this to the unsafe version is as simple as replacing the basic operator definition macro (I have that code, too. Let me know if I should post this, too). 4. Pretty much all code which alluded to a specific compiler bug/support has been removed. This includes NRVO code. I'm still not sure what level of backwards-compatibility or specific compiler code we wanted so I just code to C++03/C++11. 5. I haven't added noexcept yet (mainly because I haven't had the time to learn more about noexcept yet). My testing has nearly all so far been done in VS2012 which has an "illustrious reputation" with standards compliance. I also have access to VS2010 and MinGW (GCC 4.7.2) so I'll try testing these later, but I don't have a setup for testing compilers in Linux/Unix/Mac or any other compilers we may want to support (Clang, Intel, Embarcadero/Borland, etc.). A few questions I have: 1. In v1 operators were always considered commutative/non-commutative. The composite operators take advantage of this fact, and I have the composite operators implemented with the same assumptions. Are there any composite operators we want to provide which make different assumptions (for example, a matrix has commutative add/subtract, but non-commutative multiply)? 2. I'm a little unsure if the <boost/iterator.hpp> include is still required. It compiled fine without it, but I haven't tried out all the features to see if it is indeed required. Anyone know why we should keep this include in v2? Feedback would be appreciated, thanks.

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GSoC : Boost.Math Bernoulli Numbers
by Gaurav Deshmukh 26 Apr '13

26 Apr '13

Hi, I am Gaurav Deshmukh, CSE second year student. I am interested in the idea of adding support to Bernoulli's number to special functions in Boost.Math for GSoC-2013. I have the experience of using Boost libraries and generics in C++. I have experience to use git. I have also learned to use Boost Test upto some extent. I have tried to implement naive Akiyama–Tanigawa algorithm for second Bernoulli numbers using multi-precision boost class *'number' (cpp_dec_float_50**)*. I have attached two files. The header file *bernoulli.hpp* contains the function to calculate second bernoulli number for n<3000. *exampe.cpp *is made to test the bernoulli.hpp .

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[gsoc-2013]Approximate string matching
by Yu Jiang 26 Apr '13

26 Apr '13

Hello, I'm Yu Jiang, currently a master student from Tsinghua University in China. I'm attracted by the idea of "approximate string matching" since it's highly related about my research and also my interest. I have seen in a previous discussion, another student proposed to implement some basic matching functions such as "edit distance" for boost. He said by using dynamic programming, the time complexity is O(m*n). However, if we give a threshold T and only report the exact edit distance if it's no larger than T, the complexity can be O(T * min(m,n)). I think sometimes we just need to decide whether the edit distance is small enough. Furthermore, I'm also interested in approximate string search. That is, given a query string word Q and a candidate word set S, find all the strings in S who have the edit distance no larger than a threshold T with the query string. This is very useful in many area such as data integration, and I have strong knowledge in fast algorithms to solve this. So, is it compatible for gsoc 2013 and for boost? Looking forward to your opinions. Thanks, Yu

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[operators] The future of Boost.Operators
by Daniel Frey 26 Apr '13

26 Apr '13

Hello, for a long time there hasn't been any significant update of Boost.Operators and I had an easy job being its maintainer for the past 10+ years. I guess that will change soon. :) I would like to discuss the future of Boost.Operators, as several issues and options have piled up in the past. Here are some points to take into account: 1) Support for rvalue references to generate fewer temporaries. (where available) 2) Support for noexcept. (where available) 3) Support for constexpr if this is applicable at all. I haven't found the time to properly research it yet. 4) Allow dedicated commutative and non-commutative versions for several operators, leading to fewer temporaries for commutative versions in several cases. 5) Remove work-arounds for ancient compilers, general cleanup. I worked on a clean rewrite (called df.operators) which supports 1), 2) and 4) (and obviously 5)) and published it a few weeks ago on GitHub, see <http://github.org/d-frey/operators/>. It is meant to show one option, but it is not a suitable replacement for Boost.Operators in its current form. If it turns out to be useful as a test-bed for the next version of Boost.Operators, I will be glad to improve it into this direction but the future of Boost.Operators does not depend on it. That said, I'd like to invite anyone interested to have a look. If applicable to the future of Boost.Operators, please provide feedback on this mailing list. If feedback only concerns df.operators but not Boost, please don't spam the list and write to my private email, thanks! Some issues which need to be discussed/solved for Boost.Operators' future: 1.1) Which implementation should be used for maximum performance/compatibility? 1.1.1) Pass-By-Value as suggested by Dave Abrahams' article. (<http://cpp-next.com/archive/2009/08/want-speed-pass-by-value/>) 1.1.2) Overloads for Pass-By-Const-LValue-Reference and Pass-By-RValue-Reference. (as in df.operators) See below for why I decided to create 1.1.2) as an alternative to 1.1.1). 4.1) Decide for a default. 4.1.1) Commutative by default (as the current version of Boost.Operators assumes), non-commutative if explicitly requested by the user. 4.1.2) Non-commutative per default, commutative versions need to be explicitly requested by the user. (as in df.operators) 5.1) The main issue is probably the base-class-chaining. 5.1.1) Keep base-class-chaining, makes VC++ happy. (apply EBO and keep the object size small) 5.1.2) Drop base-class-chaining, stop punishing the rest of the world for VC++'s inability to apply the EBO for multiple inheritance. (I might be a bit biased here…) 5.1.3) Any other option I fail to see? (If a MS-employee would like to provide some information on if/when the EBO-problem will be fixed (here or in private email), I'd be grateful. If it is already fixed, I apologize, but the last information I got about VS2012 suggests EBO is not applied for multiple inheritance.) I think this should be enough to get some discussion going… Best regards, Daniel Why 1.1.2) as an alternative to 1.1.1)? Consider the following test program: #include <iostream> #include <utility> struct A { A() { std::cout << "A::A()" << std::endl; } A( const A& ) { std::cout << "A::A(const A&)" << std::endl; } A( A&& ) { std::cout << "A::A(A&&)" << std::endl; } ~A() { std::cout << "A::~A()" << std::endl; } A& operator+=( const A& ) { std::cout << "+=" << std::endl; return *this; } }; // #define BY_VALUE #ifdef BY_VALUE A operator+( A lhs, const A& rhs ) { lhs += rhs; return lhs; } #else A operator+( const A& lhs, const A& rhs ) { A nrv( lhs ); nrv += rhs; return nrv; } A&& operator+( A&& lhs, const A& rhs ) { lhs += rhs; return std::move( lhs ); } #endif int main() { A a, b, c, d; A r = a + b + c + d; } The above code, compiled with G++ or Clang prints: A::A() A::A() A::A() A::A() A::A(const A&) += += += A::A(A&&) A::~A() A::~A() A::~A() A::~A() A::~A() A::~A() If you define BY_VALUE, it prints: A::A() A::A() A::A() A::A() A::A(const A&) += A::A(A&&) += A::A(A&&) += A::A(A&&) A::~A() A::~A() A::~A() A::~A() A::~A() A::~A() A::~A() A::~A()

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 26 Apr '13

26 Apr '13

> > I'm not ruling out the merit of a Boost.Thread threadpool. For me personally > > though, the hurdle is very significantly raised: you need to strongly prove > > to me why your proposed thread pool is much superior to a Boost.ASIO based > > threadpool. Otherwise I will zero score the GSoC proposal, because in the > > end we need other proposed projects more. > > Superior in what way? Performance-wise, interface-wise? What advanced > features would you want from a thread pool to make it superior to the > presented implementation? That's for the applicant to decide. Any proposal needs to be very significantly better than something based on existing features to pass muster not just with Boost, but with Google themselves. There is always an assumption against duplication of existing functionality just for the sake of it. Niall

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[type_erasure] error in type-erased iterators
by Adam Wulkiewicz 26 Apr '13

26 Apr '13

Hi, iterator< ::boost::no_traversal_tag, ...> defines constructible<T()> requirement. This however musn't be meet in the case of incrementable and single-pass iterators. It should probably be moved to the iterator< ::boost::forward_traversal_tag, ...> Patch attached. Regards, Adam Wulkiewicz

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Fwd: [gsoc 2013] boost.multiprecision
by Sagar Massand 26 Apr '13

26 Apr '13

Hi, I wanted to submit a proposal but I am not sure right now if I am going in the right direction.It would be great if you could guide me here. I was thinking of implementing karatsuba multiplication in the initial stages, complete with a testing of the implementation, and then move on to Schonhage-Strassen and other fast-fourier transform algorithms in the last one and half months seeing that our primary requirement is for numbers uptil 1000 digits. I was also thinking of the implementation of some other division algorithms like Goldschmidt, Newton-Raphson etc. A complete link to my proposal can be found below: https://docs.google.com/file/d/0B5iapFjtoO7GTVR2eGhJd2dXZHM/edit It would be great if you could give suggestions to improve this.Thanks. Regards, Sagar Massand

1 0

[gsoc-2013] Boost.Thread/ThreadPool project
by Dan Lincan 26 Apr '13

26 Apr '13

Hello, My name is Dan Lincan. I'm a 4th year undergratuate student in Computer Science at the "Politehnica" University of Bucharest and I'm interested in the project "Boost.Thread/ThreadPool". I have studied the documents provided as resouces and I would really appreciate if you helped me better understand this project. Are there any tasks that are meant to get solved for the proposal? How do I start? I am aware that it will not be an easy task at all, especially because I don't have much experience with boost, but I'm willing to learn and work as much as it is needed to get it done. Thank you for your time, Dan Lincan

3 15

[Runtime Parameters Reference]Command Line Argument
by Hemanth Choudary M V (RBEI/ETA1) 26 Apr '13

26 Apr '13

Hi, I would like to run selected test cases from multiple tests suits. Pl let me know the command line argument to be passed. Mit freundlichen Grüßen / Best Regards, Hemanth Choudary MV RBEI/ETA1

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Re: [boost] Live read-only GIT mirrors of Boost trunk SVN
by Niall Douglas 25 Apr '13

25 Apr '13

> >The live GIT mirrors of Boost trunk SVN have become a bit stale in recent > >months [...] > > I tried making a mercurial mirror of the Boost trunk SVN and found > that it took so long to do the conversion process, that I could never > get it to complete on my home computer with cable modem internet > access, but I could get it to complete on a shell account with faster > trunk access. I simply allocated an OpenVZ container on my cloud with 64Mb of RAM and 128Mb of swap. > I also found the resulting repository was *huge* because I had *every* > revision of boost ever recorded in the svn repository. Github reckons the entire mirror consumes 700.40Mb. No idea if that's good or bad. > I'm curious if you had different experiences when making a git > repository. To be honest, the process was very straightforward. I configured it as per subgit's instructions. I set it running. It OOMed a few times, but hardly unsurprising with 64Mb of RAM for the VM. I simply restarted when it did. And after a day or two it completed (note that the cloud hardware is a 2Ghz Core 2 without SSD). Better hardware would be far faster. > I am more familiar with mercurial than git, and I wanted to make a > local mercurial repository so that I could work on my changes locally > and checkpoint them using the version control system instead of manual > backups. AFAIK, there's no way to record local changes with > versioning using subversion, there's only committing to the remote > server. Ah, getting subversion commits to match git commits that's subgit's problem :). Subgit gives you three sync options, "safe", "somewhat safe" and "not safe". "safe" locks both subversion and git repos during the sync, however long that takes, and during which no pushes nor pulls nor checkouts may happen. So long as you can live with that (I can), the live two way mirroring works well, but it could be frustrating for users of busy repos. Niall

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Re: [boost] [operators] The future of Boost.Operators
by Andrew Ho 25 Apr '13

25 Apr '13

> Maybe we're talking past each other. I have 3 overload set variants in > mind: > > (A) > T operator?(T, T); > > (B) > T operator?(T const &, T const &); > ... > T operator?(T&&, T&&); > > (C) > T operator?(T const &, T const &); > ... > T&& operator?(T&&, T&&); > > AFAICT, neither (A) nor (B) have any safety issues. Oh, but now I see the > problem with (C): T&&'s are implicitly convertible to T&'s...that's what I > was missing before. Sorry for being dense. > > So if you do > > T& a = b + c; > This succeeds in VS2012 with all (no compile or runtime problems, oddly VS2012 extends the lifetime of ref returned by C to be valid), and fails with all in gcc 4.7.2 (compiler error) :P > invalid initialization of non-const reference of type 'T&' from type 'T&&' Yep, this is what happens in gcc for me. > > I swear I just tried a T& y = static_cast<T&&>(x) on gcc and finding it > compiled fine. This gave a compiler error for me. > Now you can ask the same question with T const& instead... Compile succeeds, with only two operands the called overload returns a T, not T&& so there's no problems. If you had: const T& r = a + b + c; (A) and (B) are perfectly safe, but (C) will have runtime issues. Same goes for: T&& a = b + c; T&& r = a + b + c; First line doesn't have any problems with (A), (B), or (C) because of which overload is used. The second line (A) and (B) have no problems but (C) will have runtime issues. Of course, (C) will have a few extra temporaries created (which may or may not be optimized away). The question originally posed is do we: 1. Ignore this problem with (C) to get better performance and just document the problem? 2. Implement (B) to take advantage of move semantics with no internal problems, albeit with a few temporaries being created (if they aren't optimized away by the compiler)? 3. Implement a user-accessible macro switch to let the user decide globally As Jeff said, (3) is ugly especially when linking different codes together, but does provide the most options to the user. (2) isn't necessarily the most efficient but is completely safe. It may also end up being just as efficient as (1) if compilers support the optimization to remove unnecessary temporaries. Daniel's argument is that the problems which occur with (C) are typically a result of user error, and (C) in general guarantees the least amount of temporaries being used. Are there any cases where the problems described above with (C) would be a result of intended behavior with no acceptable work-around? Hopefully we're on the same page now.

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Google Summer of Code Proposal Feedback
by Niall Douglas 25 Apr '13

25 Apr '13

> aware of GSOC until recently. I had strongly considered writing a proposal > for Boos.ASIO, but I fear my lack of experience with Linux, POSIX, and > concurrency in general might prove to be too great of an obstacle. If the > subject matter can be learned relatively quickly, I would love to discuss > what such a project would require with the mentor, Niall Douglas, or a > community member who has is familiar with the project. I'm hardly "the" mentor in Boost.ASIO. I'm probably just the only one to have registered as a potential mentor so far. It's still early days. A lot more potential mentors will register in time, then depending on project scoring and people's availability and of course Google's preferences, we'll see what turns out. > My original proposal probably isn't unique, and much to my chagrin as I > read the hints for successful proposals it seems a popular topic. I am of > course suggesting a project dealing with Trees. Rather than suggest > building a generic tree, I am suggesting the start of a tree library, or > the addition of several types of trees to existing libraries, as I am not > sure which is more appropriate. An awful lot of students expose their ignorance of what Boost, or indeed the C++ standard library, provides during GSoC. It really doesn't help them to be scored well which is why Boost strongly recommends that students discuss their ideas here first before submission. 95% of the time their idea is already implemented. For example, there are multiple tree implementations in the C++ STL and Boost. Look into Boost.Intrusive for example. > Because trees are such a fundamental data type in computer science, I have > found it difficult to understand why there are no explicit tree classes in > the c++ standard. They generally don't have "tree" in their name ;) > tested in an afternoon, while implementing a Red Black Tree would take > considerably longer, yet the C++ standard has linked lists and not Red > Black Trees. Red-black trees are called std::map<>, std::set<> et al. in C++ since 1998. Of course std::map<> et al. doesn't *have* to be implemented as red-black, but most implementations do since the SGI STL defined std::map<> using stl_tree<>. > The library I am proposing should eventually be able to satisfy almost > anyone requiring the use of a tree. It should have many different types of > trees, Binary trees, AVL Trees, Red Black Trees, Treeps, B-Trees, > Skip-Lists, etc. It should support common methods of traversal, inorder, > preorder, postorder, and user defined traversal methods. Eventually, the > library should support an n-ary trees and their operations. Trees in the > library should also be performant, fail gracefully, be well documented, > unit and integration tested, as exception safe as possible, and, someday, Look into Boost.Intrusive. They're the most appropriate category for what you propose. Niall

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Discussion Policy
by Rob Stewart 25 Apr '13

25 Apr '13

If you're relatively new to this list, you may not have taken the time to read Boost's discussion policies[1]. Even if you've been on the list for a while, reviewing the policies may be educational. Thanks for your efforts to make discussions easier and more consistent for all. ___ Rob (Sent from my portable computation engine) [1] http://www.boost.org/community/policy.html

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Re: [boost] Going forward with Boost.SIMD
by Niall Douglas 25 Apr '13

25 Apr '13

> A GPU is an accelerator for large regular computations, and requiring sending > memory and receiving it back. It's also programmed with a very constrained > programming model that cannot express efficiently all kinds of operations. > > A CPU, on the other hand, is a very flexible processor and all memory is already > there. You can make it do a lot of complex computations, irregular, sparse or > iterative, can do dynamic scheduling and work stealing, and have fine-grained > control on all components and how they work together. :) You're actually wrong on that, and it's one of the first big surprises anyone who sits on ISO committees experiences: the change in scope of definitions. When you're coming at things from the level of international engineering standards, a computer's CPU is not defined as anything approximating what any of us use on a regular basis. It includes large NUMA clusters, it includes Cray supercomputers all of which don't do SIMD anything like how a PC does. It *also* includes tiny embedded 8-bit CPUs, the kind you find in watches, inlined in wiring, that sort of thing. Some of those tiny CPUs, believe it or not, do SIMD and have done SIMD for donkey's years, but it's in a very primitive way. Some of those CPUs, for example, work in SIMD 3 x 8 bit = 24-bit or even 3 x 9 bit = 27-bit not 32-bit integers, that sort of thing. Yet international engineering standards must *always* target the conservative majority, and PCs or even CPUs designed more recently than the 1990s are always in a minority in that frame of reference. Don't get me wrong: you could standardize desktop class SIMD on its own. But generally you need to hear noise complaining about the costs of lack of standardization, and I'm not aware of much regarding SIMD on CPUs (it's different on GPUs where hedge funds and oil/gas frackers regularly battle lack of interop). > However, SIMD has been here for 25 years and is still in the roadmap of future > processors. Across all this time it has mostly stayed the same. > > On the other hand GPU computing is relatively new and is evolving a lot. > It's also quite trendy and buzzword-y, and is in reality not as fast and versatile as > marketing makes it out to be. > A lot of people seem to be intent on standardizing GPU technology rather than > SIMD technology; that's quite a shame. Thing is, had Intel decided Larrabee was worth pushing to the mass market - and it was a close thing - PC based SIMD would look completely different now and we wouldn't be using SSE/NEON/AVX which is really an explicit prefetch opcode set for directly programming the ALUs and bypassing the out of order logic, not true SIMD (these are Intel's own words, not mine). As it is, convergence will simply take longer. Some of those new ARM dense cluster servers look awfully like Larrabee actually, 1000+ NUMA ARM Cortex A9's in a single rack, and their density appears to be growing exponentially for now. Given all this change going on, I'd still wait and see. Niall

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Google Summer of Code Proposal Feedback
by Paul Kirth 25 Apr '13

25 Apr '13

Hello Boost community, I am a student interested in the Google Summer of Code (GSOC), and have a few proposals in mind. If I have posted this in the wrong place, my apologies, but applicants are encouraged to post to the mailing list, and after some research this seemed like the best list to post to. I have an original proposal for Boost, and strong interest in the Boost.ASIO idea. I've decided to seek some feedback from the community on their feelings about my idea, in the hopes that I can better define them, and increase my chances of success in being selected for the GSOC. I realize it is a bit late to begin discussing proposals, but I wasn't really aware of GSOC until recently. I had strongly considered writing a proposal for Boos.ASIO, but I fear my lack of experience with Linux, POSIX, and concurrency in general might prove to be too great of an obstacle. If the subject matter can be learned relatively quickly, I would love to discuss what such a project would require with the mentor, Niall Douglas, or a community member who has is familiar with the project. *About Me* First, let me begin with a bit about myself. My name is Paul Kirth, and I am currently pursuing a masters in Computer Science. This statement may be a bit misleading, however, as I received my BS in Civil Engineering from UCLA in 2005, and have only recently decided to pursue a course of study in Computer Science. I have for the last two years taken CS classes to prepare for Masters level courses, but am still a bit of a novice in CS. I would say that I am at about a 3rd year level in CS, proficient in C++ and python, and competent in Java, with a limited amount of assembly, and very little work in concurrency. I have not spent much time doing engineering work in the last few years, as my focus has been on my education, but I was fairly good at solving linear systems, and had a good amount of experience with design and collaboration. As an undergraduate I made the mistake of not pursuing summer internships or jobs, and as a result I found that many of my peers had a much easier time with our courses as a result of their work experience. After all, 20-30 hours a week solving engineering problems will generally make you more proficient at solving them than someone who doesn't. I do not wish to make the same mistake with my new career path, and desperately want to gain experience in professional software design, and in working on a collaborative project. I am keenly aware of my lack of experience, and really wish to use this opportunity to push myself, and gain as much expertise as possible during the few months of the summer. *Original Proposal* My original proposal probably isn't unique, and much to my chagrin as I read the hints for successful proposals it seems a popular topic. I am of course suggesting a project dealing with Trees. Rather than suggest building a generic tree, I am suggesting the start of a tree library, or the addition of several types of trees to existing libraries, as I am not sure which is more appropriate. Because trees are such a fundamental data type in computer science, I have found it difficult to understand why there are no explicit tree classes in the c++ standard. I have read the arguments that there is no standard use for a tree, and as such it cannot be made to satisfy enough users. I have read more arguments stating that std::sets and std::map use tree structures underneath their interface. Furthermore I have read in several places that it is common to use Boost.graph to make trees. Trees have myriad uses, and a library implementation should consider this heavily when designing the data structure, but trees are common enough to warrant a standard implementation in the same way as lists, queues, and stacks. I will concede that trees can be considered, and in fact are, graphs, and that many graph algorithms are very powerful tools. But trees don't always need those algorithms, and graphs don't always maintain the tree in the way we wish. Using an std::set or std::map is not the same thing as using a tree, regardless of how they are implemented. Conservatively, a linked list can be fully implemented and tested in an afternoon, while implementing a Red Black Tree would take considerably longer, yet the C++ standard has linked lists and not Red Black Trees. This seems a bit counter intuitive. We have a relativity simple data structure in the standard, and a more complex one is not. I'm sure that linked lists are more common than red black trees, but by how much? If self balancing binary trees are considered a fundamental data structure by every computer science curriculum, why aren't comprehensive, reliable implementations of them part of the standard, or widely available in 3rd party libraries like Boost? The library I am proposing should eventually be able to satisfy almost anyone requiring the use of a tree. It should have many different types of trees, Binary trees, AVL Trees, Red Black Trees, Treeps, B-Trees, Skip-Lists, etc. It should support common methods of traversal, inorder, preorder, postorder, and user defined traversal methods. Eventually, the library should support an n-ary trees and their operations. Trees in the library should also be performant, fail gracefully, be well documented, unit and integration tested, as exception safe as possible, and, someday, concurrency safe/compatible. I'm unsure of the Boost stance on inheritance is, but my initial feeling is that users should be able to use tree classes as base classes if they desire. Proposing a large library as a summer project is ridiculous, hence I am proposing a start to this library, containing a few tree classes that can be implemented, tested, and documented within a few months, and a set of standards for new entries in the library. I don't expect the whole library to immediately be accepted into Boost, but the project will aim to meet those standards, with a long term goal of eventually being included into Boost. My research has found several projects that implement single tree classes, or groups of tree classes, but no tree library. A good c++ example is the rbrees project at https://code.google.com/p/rbtrees/ , or python has a few implementations of trees, such as bintrees 0.3.0, https://pypi.python.org/pypi/bintrees/0.3.0, which is a binary tree library, containing BinaryTree, AVLTree, and RBTree classes. I feel that bintrees 0.3.0 is a good project to mimic in the early stages, as binary trees are fairly easy to implement, test, and maintain with AVL and RB Trees. I am comfortable with binary, AVL and Red Black Trees, and feel very confident in my ability to implement them. I would like to do more, and push myself this summer, but I am not sure how much work unit and integration testing are, how long they take, and how much extra time is required for classes/libraries to be refined to Boost standards. I am sure that this time is non trivial, but as a student I'm very unsure about how much time things take, or how much time they should take. In general I would like to work on a project that would expose me to more new ideas, but I really think the world deserves access to a C++ tree library that can have some guarantees for performance, and is part of a larger, well documented, highly respected library. I understand that this project is virtually guaranteed to take more that one summer's worth of effort, and I am comfortable with staying involved in the project beyond the length of GSOC, or having the work done absorbed into another library/project. Whether or not this project is accepted into GSOC, if there is support for this effort in the community I would love to help as I am able. Obviously if I am working this summer my commitment will not be able to be as substantial, but I do feel strongly about the need for standard, performant, reliable tree classes in c++. Thank you for reading my lengthy first post to the mailing list. I hope to have more discussions with this community in the future, and I am eager to hear your thoughts about how this proposal could be improved. -- Paul Kirth (310) 709-2516

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proposal for date_time implementation
by Shamsher Siddiqui 25 Apr '13

25 Apr '13

hi mentors plz review my project and give me suggestion to improve to my proposal Name :Shamsher Ahmed College/University:University Insititute of Engineering &Technology,Chandigarh,India Course/Major:Computer Science & Engineering Degree Program:Bachelor of Engineering Email:mail.shamshersiddiqui@gmail.com Homepage:Not yet Availability: How much time do you plan to spend on your GSoC? I can work full time to complete this project. What are your intended start and end dates? I will start the project according to GSOC 2013 schedule but i will try to finish the project 2 weeks before so that I can have the necessary time for debugging and for unforeseen situation it occurs. What other factors affect your availability (exams, courses, moving, work, etc.) ? My semester exam will get start from 18 may and it will end on 28 may .So I will have complete time to dedicate. I don’t have any course or work during this summer . Background Information: • Please summarize your educational background (degrees earned, courses ,taken, etc.) I passed out 10+2 from Indian School Certificate in 2010 and I am currently pursing bachelor of engineering from university institute of Engineering & Technology, Chandigarh Till now I mainly focused in learning programming language (C,C++,Java). I have mastered over Java and c++ but scratchy in C.I have also taken course on Algebra, Calculus, Data Structure & Algorithm ,database etc etc. • Please summarize your programming background (OSS projects, internships,jobs, etc.) This will be my first OSS project at such large level. I have developed many things in c++ & Java. During my last summer I have done my internship in slr infotech ,a small software firm . • Please tell us a little about your programming interests : I am programming from 8th grade .In 10 and +2 board exam I obtained 96 and 97 respectively in my computer science subject. I love to code for hours .And most important thing about open-source I like about is sharing, helping and hacking code . • Please tell us why you are interested in contributing to the Boost C++ Libraries? Boost c++ Libraries are one most powerful libraries of c++ used by many well known organizations .It is cross platform library which has high efficiency And it goes together with standard template library in c++. I will get support from boost community and it is documented very well which makes it very easy to understand and if any bugs comes than it is easily recognized and eliminated , lastly while working with bright minds I will be able to learn from them and impart my experience , knowledge to other developers • What is your interest in the project you are proposing? Libraries were mystery for me when I started learning my first programming language c but after some time I was able to perform the same task without using library but there was increase in time and length of code for doing the same program.I want to develop this project because it will increase the reusability of code and in Boost community best minds works together to give the one of the best libraries of c++. Date library will be always used in every development project whether big or small and When I read this project https://svn.boost.org/svn/boost/sandbox/chr ono_date/libs/date/doc/date.html .This is small library but will be most efficient and will be able to perform all task and save time ,reusability of code is very high. • Have you done any previous work in this area before or on similar projects? No ,I haven’t done any project regarding libraries but I am using libraries in my other project. But me and my friend are developing a tagging software which creates a folder on the basis of album,artist,track number etc. We have implemented internal structure but GUI part is left which my friend is working on. and developed small games in c++ as my project assignment. • What are your plans beyond this Summer of Code time frame for your proposed work? After Summer of code ,I will remain involve with the boost c++ community and I would like to add more feature to current project.Secondly I will work with the boost community in building in their library because I love coding for long hour. I enjoy this work. • Please rate, from 0 to 5 (0 being no experience, 5 being expert), your knowledge of the following languages, technologies, or tools:  C++: 4  C++ Standard Library: 3  Boost C++ Libraries: 2  Subversion :2 • What software development environments are you most familiar with (Visual Studio, Eclipse, KDevelop, etc.) I generally use Qt creater or Visual studio depending on the operating system I am using . • What software documentation tool are you most familiar with (Doxygen, DocBook, Quickbook, etc.)? I am familiar with Doxygen Project Proposal Goals & Implemenatations 1) Construction of Date: • Date can be represented in two ways field representation or as an serial representation . In field based representation(YMD) date value is constructed from individual year,month,and day value in three integral value. In serial reprensentation(SERIAL) data values are stroed in intergral number of days from an implementation defiend epoch date, there is third hybrid version to represent the date which implemantd the both representation and it is named HH_YMD_SERIAL_X where x represents the size of types in byte. • Providing support for entering the date in form YDM(year,day,month) which is lacking currently in chrono:date library • No invalid dates can be entered considering range cheaking ,non existent date if entered bad_date exception is thrown . • Constructing constant object for day,week_day. Eg. last/may/2000 represents 31 may 2000 • Construction of meta data for date 1) Leap year flag 2) Nth day of month 3) Nth weekday month 2) Arithematic Operation On date Date airthematic can be done on three units i.e day,month,year.In chrono date ::calendar(Gregorian calendar) length of month and year is not fixed : • day arithematic 1) Adding number of days to date until range doesn’t exceed 2) Implementing last day arithmetic to avoid the bad date excepti Eg. aug/last/2011 +months(1)= sep/30/2011 aug/31/2000 +months(1)=sep/31/2000 //invalid date bad date excep thrown • month arithmetic Month arithmetic is quite complex compared to day arithmetic since number of are not fixed . 1) (month day <=28 || month day =last day ) always add month 2) month day =29 cheak for leap year and than add month 3) Month day>=30 add but don’t add if resulting month is feb 4) Using constant objects for month arithmetic. • year arithematic 1) Always add year to date considering the condition of leap year 2) Reversal of date back to original date 3) Usage of last day during year arithematic During any of the airthematic operation result should not be an invalid date if it occurs than bad_date exception is thrown. 3) InterConversion field representation & serial representation Some operation are quite fast on field but airthematic operation are much faster on serial campared field representation .So it is necessary to provide the inter-coversion so that it can be easily converted from one representation to another. 1) Constructing bi-directional conversion of serial and field by making use of static cache to optimize conversion 4) Building function for week days & date formatting 1) weekday of a date used. 2) nextweek day of date used. 3) previous weekday of date used. 4) finding number of weeks in month 5) formatting of date according of all types 5)Interoperability with other calendar Current chrono::calendar is Gregorian calendar which exist everywhere in date & time library of every programming language.(c,c++,java) and ISO 8601 and POSIX. This section provides conversion of chrono calendar to client calendar. 1) Conversion of chrono ::calendar to Julian Calendar 2) Conversion of chrono :: calendar to Hebrew calendar 3) Conversion of chrono :: calendar to hindu calendar 4) Conversion of chrono :: calendar to Chinese calendar 5) Conversion of chrono :: calendar to Buddhist calendar 6) Conversion of chrono :: calendar to Islamic calendar Hindu ,Chinese ,Buddhist ,Hebrew(Jewish ) calendars are lunisolar calendar with a very little difference. Julian, Gregorian are very much similar except the method of finding the leap year. Islamic calendar is lunar calendar(totally dependent on moon ) which is quite unpredicatable. Hence accurate conversion is rare. TimeLine Until 17 June :Community bonding , understanding boost c++ libraries ,discussing with mentor about the details of proposal . 17 June to 27 June: Construction of date 28 June to 12 july : testing &debugging of construction of date and implementing date arithemetic 13 july to 29 july (Mid term evaluation) : implementation of interconversion of serial and field representation and testing ,debugging and making more efficient the previous code develop. 30 july to 15 August :Implementation of date formatting and developing function on weekday. 16 August to 30 August: testing ,debugging and aadding more feature to weekday and implementation of interconversion of calendar. 31 August to 23 Sept:testing ,debugging ,making efficient the whole code .

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Fwd: [asio]Extension for audio device service
by adrien courdavault 24 Apr '13

24 Apr '13

Hello. I make this new thread to be clearer. There is currently no way to manage audio endpoints cconnection easily. It looks like some people might find this usefull (as I do), and I've been suggested on the boost dev list to try to detail this, as an extension to Boost.ASIO. For this reason I create this thread. I'm trying to make a very basic first draft of the concepts and see if this may be a good idea. I attached here the first things I've written. This is very short and general. I would like to know: * do you think I'm going in the right direction by seing this as Boost.ASIO extension. * do you have suggestions * would someone like to participate ? Thank you

2 3

[gsoc-2013]Boost.multiprecision project
by Sagar Massand 24 Apr '13

24 Apr '13

Hi, I wanted to submit a proposal for the boost.multiprecision project. Please find attached the files:1)Proposal for the project 2)Naive code for karatsuba multiplcation in C. It would be very kind of you if you could give me suggestions, point out flaws etc. in this. Regards, Sagar Massand

1 0

Going forward with Boost.SIMD
by Mathias Gaunard 24 Apr '13

24 Apr '13

Hi, This week I presented a proposal to the C++ standards committee to provide a standard library component for SIMD computation based on the library in development Boost.SIMD (not yet a Boost library). I was hoping to get feedback on the interface and establish an API that would satisfy hardware and compiler vendors. Unfortunately the concurrency/parallelism group has decided that they do not want C++ to provide types representing SIMD registers. I'm afraid I don't quite understand the rationale for such a refusal; proposing more high-level constructs similar to valarray (or to our own library NT2) was suggested, but that's obviously a more complex and limited API, not a basic building block to program portably a specific processor unit. Development of Boost.SIMD will still proceed, aiming for integration in Boost, but standardization appears to be definitely out of the question. Any feedback of the API presented in the proposal is welcome. <http://open-std.org/JTC1/SC22/WG21/docs/papers/2013/n3571.pdf>

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[Runtime parameters reference]Regarding Call Stack Trace
by Hemanth Choudary M V (RBEI/ETA1) 24 Apr '13

24 Apr '13

Hello, We are running a boost unit test using command line (cmd). The command is: C:\> /c "D:\MyExecutable.exe" --run_test=testcase1,testcase2,testcase3, --report_format=xml --report_level=detailed --log_format=xml --log_level=all >test_log.xml 2>test_report.xml The output format is in XML. I would like to have the call stack for the failed test cases. Is it possible to write the call stack trace in test_report.xml or test_log.xml ? Is there any macro or Boost API can help me achieve this? Mit freundlichen Grüßen / Best Regards, Hemanth Choudary MV RBEI/ETA1

1 0

'XPath error : Undefined namespace prefix' when building boost.test docs
by legalize+jeeves＠mail.xmission.com 24 Apr '13

24 Apr '13

[Please do not mail me a copy of your followup] I get this error when I try to build the boost.test documentation and I'm not sure where it's coming from or what to do about it. Since the HTML files are commmitted to the repository, I can't tell if the documentation was actually generated or not. D:\Code\boost\svn-boost-trunk\libs\test\doc>b2 standalone ...found 39 targets... ...updating 1 target... xslt-xsltproc-dir.windows html\standalone_HTML.manifest XPath error : Undefined namespace prefix set XML_CATALOG_FILES=../../../bin.v2/boostbook_catalog.xml "d:/code/boost/boost-tools/bin/xsltproc.exe" --stringparam boost.defaults "Boos t" --stringparam chunk.toc "/D:/Code/boost/svn-boost-trunk/libs/test/doc/src/btl -toc.xml" --stringparam example.dir "file:///D:/Code/boost/svn-boost-trunk/libs/ test/doc/src/examples" --stringparam manifest "standalone_HTML.manifest" --strin gparam manual.toc "/D:/Code/boost/svn-boost-trunk/libs/test/doc/src/btl-toc.xml" --stringparam snippet.dir "file:///D:/Code/boost/svn-boost-trunk/libs/test/doc/ src/snippet" --path "D:\Code\boost\svn-boost-trunk\libs\test\doc/src" --xinclude -o "html/" "D:\Code\boost\svn-boost-trunk\libs\test\doc\src\xsl\html.xsl" "..\. .\..\bin.v2\libs\test\doc\msvc-11.0\debug\utf-boostbook-on\src\btl.docbook" ...failed xslt-xsltproc-dir.windows html\standalone_HTML.manifest... ...failed updating 1 target... D:\Code\boost\svn-boost-trunk\libs\test\doc> Any suggestions? -- "The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline> The Computer Graphics Museum <http://computergraphicsmuseum.org> The Terminals Wiki <http://terminals.classiccmp.org> Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

2 7

Re: [boost] GSOC - Boost.SQL and Boost.Thread interest
by Guillaume Nuel 23 Apr '13

23 Apr '13

Hi Vicente ! > if you are interested on one of these projects, please send as soon as possible to this ML a concrete proposal.> If both subject interest you, you can make two proposals. My main choice for Thread is: Thread.Pool (Proposal n°2 on my homepage: http://immortal-pc.info/Boost.html )General idea: ( Syntax highlighting at: http://immortal-pc.info/Boost.html#threadPool_idea ) int f1( const char* i ) { std::cout << i << ':'; // ... return 'f'+1; } int f2( const char* i ) { //... return 'f'+2; } int f3( const char* i ) { //... return 'f'+3; } int f4() { //... return 20+20+2;// 42 Power ! ^^ } int f5() { //... return 'f'+5; } int main() { // I want 5 threads for my job. Boost::Pool bp(5); // Note: A great option would be to use the "main thread" for calculations. (OpenMP like) // With this idea, 5 threads needed => 4 new theads + the main thread // // Another interesting option would be to provide switch between thread and process (fork) // I love Python multiprocessing: // http://docs.python.org/2/library/multiprocessing.html#using-a-pool-of-worke… // Note: Using, C++11 Brace-Initialization => std::initializer_list // Map function will call f1("Data1"), f1("Data2"), ... // >> ONE CALL PER parameter bp.map(f1, {"Data1","Data2","Data3","Data4","Data5","Data6","Data7"} );//!< WAITING function // "apply_async" will call {f1} with the parameter "Test" five times. // >> 1 CALL for f1 ! // >> 1 CALL for f2 ! // >> 1 CALL for f3 ! // >> f1 // f2 // f3 // -> // = paralell bp.apply_async(f1, "Test"); bp.apply_async(f2, "Test"); bp.apply_async(f3, "Test"); bp.execute();//!< WAINTING function // Or maybe a function who provide a result list for each function // Like this: std::array<int> functionsReturns = bp.get_result<int>();//!< WAITING function // And another great things from https://svn.boost.org/svn/boost/sandbox/async/libs/async/doc/html/toward_bo… // Multi-function without parameter // >> 1 CALL for f4 // >> 1 CALL for f5 // >> f4 // f5 // -> // = paralell // NOTE: same as: // bp.apply_async(f4); // bp.apply_async(f5); // bp.execute();//!< WAITING function bp.call_all(f4, f5);//!< WAITING function // Maybe a function who provide a result list for each function // Like this: std::array<int> functionsReturns = bp.get_result<int>(); return 0; } > The link doesn't worksOups. Sorry for the typo. http://immortal-pc.info/Boost.html Do you keep my proposal for Boost.SQL? Best,Guillaume

2 1

GSoC: Student applications can now be submitted
by Boris Schaeling 23 Apr '13

23 Apr '13

Student applications can now be submitted to <https://google-melange.appspot.com/gsoc/homepage/google/gsoc2013>. The deadline is 3 May. Boris

3 3

[iterator] Code/documentation mismatch in iterator_facade
by Gabriel Redner 23 Apr '13

23 Apr '13

Hi folks, I've stumbled upon an issue with iterator_facade. When creating a random access facade, one must implement the distance_to member function in order for std::distance to work. However, it looks like the arguments passed to this method are reversed from what the documentation states. Specifically, the docs [1] say (paraphrased): a.distance_to(b) is equivalent to distance(a, b). However, when I call std::distance(a, b), I find that b.distance_to(a) is invoked in the facade - the mirror image of what the docs say! This is not a problem if just wrapping some other random access iterator, but in my case the calculation of distance is nontrivial and this issue led to a rather tiresome debugging session and the solution (negating before returning from distance_to, knowing that iterator_facade will re-negate my response) is annoying to explain. Should I file a bug? A test case is appended to this message. -Gabe [1] http://www.boost.org/doc/libs/1_53_0/libs/iterator/doc/iterator_facade.html… ==================== #include <boost/iterator/iterator_facade.hpp> #include <vector> #include <iterator> #include <iostream> class vector_iterator : public boost::iterator_facade< vector_iterator, int, boost::random_access_traversal_tag> { public: vector_iterator(char tag, std::vector<int>::iterator it) : _tag(tag), _it(it) {} private: friend class boost::iterator_core_access; int& dereference() const { return *_it; } bool equal(vector_iterator const& other) const { return _it == other._it; } void increment() { ++_it; } void decrement() { --_it; } void advance(int n) { std::advance(_it, n); } std::vector<int>::iterator::difference_type distance_to(const vector_iterator& other) const { std::cerr << _tag << ".distance_to(" << other._tag << ")\n"; std::vector<int>::iterator::difference_type result = std::distance(_it, other._it); std::cerr << "result = " << result << '\n'; return result; } private: const char _tag; std::vector<int>::iterator _it; }; int main() { std::vector<int> v; v.push_back(1); v.push_back(2); vector_iterator a('a', v.begin()); vector_iterator b('b', v.end()); std::cerr << std::distance(a, b) << '\n'; } ====================

2 2

[REVIEW] Boost.Predef
by Joel Falcou 23 Apr '13

23 Apr '13

Hi all, first, I want to apologize for the delay in getting this review results out. Looks like my last email get lost at some point. Anyway, after the initial review of Rene Riviera Boost.Predef, my decision was to Conditionnally Accept Boost.Predef under the request that the comments raised during the review period were addressed. Since then, Rene worked hard on actually making those changes so I now feel confident to announce that Boost.Predef is ACCEPTED as a Boost library. Regards

1 0

GSOC 2013
by Computer Vision 23 Apr '13

23 Apr '13

Hello, I was very busy with my studies, am I late? Are there any free projects left? Kind Regards

3 2

Going forward with Boost.SIMD
by Niall Douglas 23 Apr '13

23 Apr '13

> Unfortunately the concurrency/parallelism group has decided that they do > not want C++ to provide types representing SIMD registers. > I'm afraid I don't quite understand the rationale for such a refusal; > proposing more high-level constructs similar to valarray (or to our own > library NT2) was suggested, but that's obviously a more complex and > limited API, not a basic building block to program portably a specific > processor unit. As much as a refusal can be heartbreaking, trust me when I say that indecision or indifference is worse. The fact they gave you a definite refusal is actually one of the least worst outcomes from an ISO standards proposal, because you can now move on without uncertainty. > Development of Boost.SIMD will still proceed, aiming for integration in > Boost, but standardization appears to be definitely out of the question. > Any feedback of the API presented in the proposal is welcome. > <http://open-std.org/JTC1/SC22/WG21/docs/papers/2013/n3571.pdf> If I were still part of ISO standards, I'd observe the following: 1. GPU and CPU stream computation technologies are still merging. In other words, it's too soon to standardize this technology lest we accidentally break some novel form of new convergence. Happy to reconsider post-C++14. 2. It's hard to standardize current CPU SIMD implementations due to extremely irritating inconsistencies between vendors. For example, a generic straight port of SSE2 to NEON will have awful performance because SSE2 code does a lot of flipping between SIMD and non-SIMD, and because NEON is a coprocessor on ARM that generates poor performance. Another bug bear of mine on NEON is the lack of an equivalent to _mm_movemask_epi8(), which can be emulated in about eight NEON instructions, but in so doing you'll make code which was very speedy on SSE2 pretty slow in most cases on NEON. My point here is you cannot standardize such non-uniform behavior in a universally performant way, because you'll just get lowest common denominator performance across all SIMD implementations which kinda defeats its purpose. If all vendors were like NEON, or like SSE2, then we still have to see how CUDA and OpenCL pan out long run. 3. I am unsure if C++ is the appropriate language for SIMD standardization when perhaps a meta-form of JIT compiled C++ would be much superior (i.e. you supply LLVM bytecode, and it gets delivered to a GPU/CPU/whatever). We'll have those on the table with LLVM-type compilers. In other words, I would vote to wait and see what the market throws up. I appreciate that none of these three rationale are what you want to hear. Still, I hope my observations are useful to you. None of them suggests you shouldn't proceed with Boost.SIMD. Boost has a much wider remit than just as a testing ground for future C++ standard library features. But I suspect that if SIMD ever does get standardized, it won't look like your library or proposal because it will be based on technologies which don't exist yet. Hope that helps, Niall

3 2

[log] Patch: rotating file collector (Was: Boost.Log: Any Comments?)
by Alexander Arhipenko 23 Apr '13

23 Apr '13

Hi, Just to remind the context, I'm pasting content from previous mail thread. On Tuesday 09 April 2013 18:43:05 Alexander Arhipenko wrote: >> ... >> [snip] >> ... >> >> It would be very nice to have rotation feature work the same way as in e.g. >> python logging library or Apache web server: >> * latest file has the name filename.log >> * previous file has the name filename.log.1 or filename.log.YYYY-MM-DD >> AFAIK, it's impossible to achieve in current implementation. >> >> Andrey, what do you think about this? >The library does not provide this behavior out of the box. But the file sink >uses a file collector object to collect rotated files. This collector can be >implemented by the user (it should derive from sinks::file::collector >interface) and it should be possible to implement it the way you describe. >Would you like to submit such implementation? I've added implementation of rotating file collector - the patch against boost log trunk attached. This is not the final version, I'm going at least to finish most of the TODOs. However, it would be nice to receive feedback and questions from library author as well as from people interested in this feature. Andrey, could you please find several minutes to review the attached patch? Also, I would like to discuss following question with you : rotate_file invocation in ~text_file_backend - I would prefer to have this call during text_file_backend construction phase. Regards

1 0

std::optional<T>
by Fernando Cacciola 23 Apr '13

23 Apr '13

Hi People, I'm pleased to announce that thanks to the outstanding effort of Andrzej Krzemienski who wrote the standard papers, and Ville Voutilainen who champion it during the meetings, we now have std::optional<T> in C++14! Cheers -- Fernando Cacciola www.scisoft-consulting.com

11 15

Plugin/Extension : DLL/so loading?
by Mathias Gaunard 23 Apr '13

23 Apr '13

I remember there were a couple of projects (Boost.Plugin or Boost.Extension) to support dynamic loading of a DLL/so plugin in a portable fashion in Boost. What has happened to these, and is there some code I can use somewhere?

3 4

Boost Graph Library: why are `source()`/`target()` non-member functions?
by Max Moroz 22 Apr '13

22 Apr '13

Why is `source()` not a member function of the graph class? (See http://www.boost.org/doc/libs/1_53_0/libs/graph/doc/index.html for description, and boost/graph/adjacency_list.hpp and boost/graph/adjacency_matrix.hpp for implementation.) I thought the reason was that it was a generic algorithm. But it's not. There's no interface (beyond `source()` itself) exposed by an edge descriptor that would allow `source()` to avoid digging into the implementation. If I interpret the code correctly, `source()` reads directly from the internal data structure of the edge descriptor (`detail::edge_base.m_source`), which I am pretty sure is the implementation detail (`m_source`, despite being strangely exposed as a public member, is not the standard interface; otherwise it would have been defined as such, and `source()` would have been entirely redundant.) I think I'm missing something, but what?

2 3

GSOC
by Flórián Deé 22 Apr '13

22 Apr '13

Personal Details: Name: Flórián Deé University: Budapest University of Technology and Economics Major: Engineering Information Technology Degree Program: B.Sc. Email: deeflorian(a)gmail.com Availability: -starting after the exams, best case: June 10, worst case: June 21 -ending on at the 2nd week at the university: Sept. 15 -planned time spent on GSoC: 32 to 56 hours per week, as needed -other factors: two 3-day long trips - would catch up afterwards with extra work Background information: During my B.Sc. studies I'll already have finished all courses that are related to calculus, linear algebra, number theory, combinatorics and digital technology until summer, so in my opinion, all the educational background needed is present with the exception of the Signals and Systems course in next semester, which would cover digital Fourier transforms in detail. I'd gladly make up for this by reading the needed material. As for my programming background, I've fallen in love with C and C++, which now I consider to be my main languages. I'm currently working on a project as an outsider member of the dorm's Coder team (a poker framework for AIs), and I'm also a "consultant" for students with their C/C++ assignments. As a result, I've seen, written and debugged lots of different (admittedly not so enormous) projects with different coding styles. I'm interested in contributing to the Boost Libraries because two of my friends used a quite a lot of them while researching, and their feedback was always positive. The C++11 implementations also sounded nice, so adding to this codebase as a summer project would be an honor. I wanted to do a Solar System simulator during secondary school because I thought that I could calculate the acceleration (and approximate path) of a pen somehow shot near Earth. Then after the first console-based C++ implementation I realized that doubles aren't sufficiently precise to determine if an object is near or inside a planet, so I tried to write a "double double" class - which was too childish to work both code and mathematicalwise. Since then I know that I'd needed a precise mathematical library, and that radix-2 is my best friend when calculating on CPU-s, so I think that this project would be an ideal fit. Rating of knowledge: C++ - 4 C++ Standard Template Library - 4 Boost C++ Libraries - 2 Subversion - 3 Development environments: Eclipse, Visual Studio Documentation tools: Doxygen Project proposal, schedule and milestones: I'd like to work on the Boost.Multiprecision project described on the wiki page. As the description there is more than detailed, I wouldn't like to copy all that text here, but I'd follow the main steps described. I think that the I/O and the +, - operators should be finished, and the multiplication already started by the end of July. The *, / operators should be finished by the end of August at least with the Karatsuba multiplication, interoperable with Boost.Math, and the FFT multiplication should also be started by then. The final goal would be FFT multiplication, with passed correctness tests of wide variety from the beginning of the project.

1 0

shared_ptr ordering
by Matt Bergin 22 Apr '13

22 Apr '13

Back in 2008, changing shared_ptr operator< to compare by pointer value rather than owner was discussed: http://lists.boost.org/Archives/boost/2008/10/143175.php There seem to be convincing arguments for both implementations (aliasing, consistency with equality operator etc). Is boost::shared_ptr intended to be a compliant C++11 std::shared_ptr? If so, will shared_ptr be changed to comply with [util.smartptr.shared.cmp] or is the ensuing breakage too high a price to pay for 100% compliance? Thanks Matt

2 1

[ublas] GSoC 2013 Proposal - uBLAS Math Library and Performance Optimization
by Sathyam Vellal 22 Apr '13

22 Apr '13

Hello everyone. I've been in touch with Mr. David Bellot and Mr. Nasos Iliopoulos and with their guidance and support I've written this proposal for Boost.uBLAS. The proposal can be viewed here -http://goo.gl/Qo7Ry. (This is a link to a google doc; a pdf version of the proposal). Thank you -- Sathyam M Vellal P.E.S. Institute of Technology, Bangalore, india

1 0

[config][mpl][type_traits][integer] BOOST_STATIC_CONSTANT should use constexpr
by Vicente J. Botet Escriba 22 Apr '13

22 Apr '13

Hi, BOOST_STATIC_CONSTANT could be improved to make use of constexpr. This is needed for instance to make integral_constant compliant with C++11. The patch consists in changing const by BOOST_CONSTEXPR_OR_CONST in boost/config/suffix.hpp // BOOST_STATIC_CONSTANT workaround --------------------------------------- // // On compilers which don't allow in-class initialization of static integral // constant members, we must use enums as a workaround if we want the constants // to be available at compile-time. This macro gives us a convenient way to // declare such constants. # ifdef BOOST_NO_INCLASS_MEMBER_INITIALIZATION # define BOOST_STATIC_CONSTANT(type, assignment) enum { assignment } # else # define BOOST_STATIC_CONSTANT(type, assignment) static *BOOST_CONSTEXPR_OR_CONST* type assignment # endif and in each out of line static constant definition as in template <int b1, int b2> bool *BOOST_CONSTEXPR_OR_CONST* ice_eq<b1,b2>::value; The main problem is that this is a *breaking change*: the list of concerned libraries is quite big (mpl, type_traits/integer_traits, ...) and users of BOOST_STATIC_CONSTANT would need to make this modification also. An alternative is to define a BOOST_STATIC_CONSTANT_11 that includes this modification and update the Boost libraries that could make use of the new macro without introducing a breaking change. Library providing a template class containing a field with such a change that can be specialized by the user would need to either announce a breaking change or just don't use the new macro. While this mean more changes the backward compatibility can be mastered. What do you think, it is worth try to fixing this? Best, Vicente

4 17

GSOC - Boost.SQL and Boost.Thread interest
by Guillaume Nuel 22 Apr '13

22 Apr '13

Hi Boost C++ Team ! My name is Guillaume NUEL. I'm a French student in computer security (fourth year in computer science). I'm actually making a game witch uses Boost (Thread, Signal,...). I also use CouchBase for database. I really would like mixing my game development and Boost development. My project proposal Idea : I'm mainly interesting in adding a new module: Boost.SQL for managing database: MySQL, Couchbase, … If the project proposal is not suitable, I have others interests. I would also be interesting in adding new functions to Thread abilities. So I am interested in the following topics : - Boost.Thread/SyncQueue: Provide boost::sync_bounded/unbounded_queue implementations base on the C++ Concurrent Queues proposal. Trying an adaptation of the Boost.LockFree queues to follow the same interface. - Boost.Thread/ThreadPool:Provide a boost::thread_pool class scheduling arbitrary functions based on Toward Boost Async 0.2 and extend the boost::async function to manage with this new class. Projects mentored by Vicente J. Botet Escriba I'm an expert in C++ and I have good skills in OpenMP and Cuda ( GPU ) and so in parallelization of code. Homepage: http://immmortal-pc.info/Boost.html My CV is available at http://immortal-pc.info/cv.html Thank you for taking the time to read my e-mail, I look forward to receive a response from you. With regards, NUEL Guillaume

2 1

GSoC: More mentors?
by Boris Schaeling 22 Apr '13

22 Apr '13

From Monday on students can apply for GSoC projects. Mentors can already apply at <https://google-melange.appspot.com/gsoc/homepage/google/gsoc2013>. So far we have four possible mentors (for uBLAS, odeint, graph and benchmark). Are there others who would like to mentor? Then please pick a project from <https://svn.boost.org/trac/boost/wiki/SoC2013> or propose your own (like I did a few days ago: <http://article.gmane.org/gmane.comp.lib.boost.devel/240251>). Applying as a mentor doesn't mean that you must mentor a student. Among others it all depends on if and how many student applications we will receive. But having a few more mentors just in case would be nice. :) Thank you, Boris

4 6

media > audio project (gsoc or future boost)
by adrien courdavault 22 Apr '13

22 Apr '13

Hi everyone. I read the project list for the GSOC 2013 and in Ideas I've seen the mention of Audio. I would like to know who is interested in this and if someone could give some details about this line : 'Audio library (OpenAL/FMOD/etc)' see here :https://svn.boost.org/trac/boost/wiki/SoC2013#Media I would like to know if this might be related to this: http://comments.gmane.org/gmane.comp.lang.c%2B%2B.isocpp.proposals/310 Thank you in advance. Adrien

6 11

Writing timer output to file
by Mohamed Nemri 22 Apr '13

22 Apr '13

Hi, I want customize boost::timer::auto_cpu_timer to put results in a logging stream(file, console,...). What is the best way to do that? Thanks --

1 0

[GSoC] Boost.Multiprecision project
by Jyotesh Choudhari 22 Apr '13

22 Apr '13

Hello, My name is Jyotesh Choudhari and I am from India. I am pursuing my Masters in Computer Science and Technology from Indian Institute of Technology (IIT) Bombay. I went through the ideas page for GSoc 2013 and would like to work on Boost.Multiprecision (cpp_bin_float) project. Looking at the project description, I think I have understood what needs to be implemented in this project. I have also gone through the current code cpp_bin_float.hpp and I have understood some part of it. I want to know how detailed should my proposal be? What details should I include in my proposal? What should be the deliverables for the project? Thanking you. Regards, Jyotesh Choudhari

2 1

[GSoC] Boost.multiprecision project
by Flórián Deé 22 Apr '13

22 Apr '13

Hello, I'm Florián Deé from Hungary, studying at Budapest University of Technology and Economics. I'm really interested in the Boost.Multiprecision project for GSoC 2013. A little background on myself, I'm an undergraduate software engineering student mostly into C and C++, with interests in low level programming and maths. I'm currently working on a project as an outsider member of the dorm's Coder team (a poker framework for AIs), and I'm also a "consultant" for students with their C/C++/Maths assignments (mostly calculus and linear algebra). As a result, I don't really have much free time till the exams, but I've planned, seen, written and debugged lots of different projects with different coding styles. Going through the project description, I think my skill set and interests would fit in nicely, with the exception of fast Fourier transforms, which I'm only mildly familiar with, but I'd gladly read any needed extra material till summer. So I kindly seek your guidance to help me go about my application for the GSoC 2013. Looking forward to your reply. Regards, Flórián

2 1

[ublas] bugfix for matrix operation /
by Mario Mulansky 22 Apr '13

22 Apr '13

Hi, I wanted to add an elementwise divide operations for ublas matrices using operator / Unfortunately, there is operator/ defined for matrix and integral types which hides any other operator definition (matrix_expression.hpp l. 3388) and thus makes it impossible to add this functionality. I would like to add an enable_if statement there that checks if the second argument is convertible to matrix::value_type, as is done for other operators. Who would be responsible for this small change? I can provide the according patch, it's almost trivial. Mario

4 7

[gsoc-2013] Physics Library Abstraction Layer
by Preston Hamlin 22 Apr '13

22 Apr '13

I am working on putting together a draft proposal for the project. Is there a preferred format desired? I was going to use a PDF since they are quite portable. I am somewhat confused as to the scope of the project, due to the previous posts in this thread. Is the library to be built upon a specific physics library (PhysX for instance) by utilizing existing code in the respective SDK to abstract away much of the object management? Or is it meant to be built from the ground up to create generic objects, which can then be translated into an arbitrary format for an existing library? Thank-you, -Preston

2 3

library to support async/await pattern
by Valentin Milea 21 Apr '13

21 Apr '13

Is there interest for a coroutine-based library to make asynchronous APIs easier to deal with? Typically, for each task there is cruft: chaining callbacks, managing intermediate state and error codes (since exceptions don't fit this model). The code flow get inverted and becomes difficult to follow. Recent versions of F# and C# solve this problem. They implement an await operator that effectively suspends the executing method until a task completes. The compiler takes care of transforming subsequent code into a continuation. Everything runs on the main thread, with asynchronous methods spending most time awaiting. N3328 proposes resumable functions of this kind in C++. For an immediate solution we could leverage the Boost.Context/Coroutine library. The resulting code may look like this: try { task = do_a_async(...) // yield until task done task.await(); } catch (const some_exception& e) { // exceptions arrive in awaiting context } // normal code flow for (auto& task : tasks1) { task.await(); } taskAny = await_any(tasks2); taskAny.await(); ... There needs to be a representation for Awaitable tasks (similar to std::future but non-blocking). The other requirement is to have a Scheduler (run loop) in order to weave between coroutines. Benefits: - normal code flow: plain conditionals, loops, exceptions, RAII - algorithm state tracked on coroutine stack - async tasks are composable - any async API can be wrapped Cons: - must wrap async APIs (e.g. Boost.Asio) - needs std::exception_ptr to dispatch exceptions - stackful coroutines are sometimes difficult to debug I wrote an open-source library that does this: https://github.com/vmilea/CppAwait. It's far from Boost style but the concept looks sane. For a comparison between async patterns please see: https://github.com/vmilea/CppAwait/blob/master/Examples/ex_stockClient.cpp Making a Boost version would involve serious redesign. So is this worth pursuing? Thanks!

5 9

Re: [boost] GSoC: More mentors?
by Christopher Kormanyos 21 Apr '13

21 Apr '13

> From Monday on students can apply for GSoC projects. > Mentors can already apply at > <https://google-melange.appspot.com/gsoc/homepage/google/gsoc2013>. > So far we have four possible mentors (for uBLAS, odeint, > graph and benchmark). Are there others who would like > to mentor? Then please pick a project from > <https://svn.boost.org/trac/boost/wiki/SoC2013> or propose > your own. > Thank you, Boris Hello, Christopher Kormanyos (who is me) just signed up as a potential mentor for the GSoC projects with Boost.Math and Boost.Multiprecision. We have already had contact with some good candidates. Thank you. Sincerely, Chris.

1 0

GSOC - Boost.uBLAS interest
by deck léa 21 Apr '13

21 Apr '13

Hi Boost C++ Team ! My name is Lea Deck, I'm French and I study in fourth year in computer science (security in computer science), but I really like mathematics. So I look for projects that mix the two. I would be interesting in adding new mathematics properties to your uBLAS libraries, like Hadamard, Toeplitz and Block matrices, the generation of matrices, Strassen multiplications and possibly new algorithms. You also alluded to the Bernoulli numbers, but I don't see any mention in the list of new features. Is the project still available? If so, should its implementation also contain the Bernoulli polynomials? About the question of optimisation, I have some skills in Cuda (GPU) and OpenMP and so in parallelization of code. So I am able to produce a correct parallelized code. Also, my knowledge of C++ is beginning to spread to the use of C++11 ( including unordered structure map). One last question, what do you mean by "Pretty display" in your list of new features? My CV is available here <http://dla.immortal-pc.info/>. ( http://dla.immortal-pc.info/) Thank you for taking the time to read my e-mail, and I look forward to receive a response from you. With regards, DECK Léa

1 0

[GSoC 2013] SVN?
by Vicente J. Botet Escriba 21 Apr '13

21 Apr '13

Hi, would all the GSoC projects be stored under SVN? Best, Vicente

3 5

Qustion about GSOC Project
by Hardy Huang 20 Apr '13

20 Apr '13

Hi, there. I am a graduate student in Peking University. I have known Boost library for long. And I used it for several times. This year I wanted to get involved in GSOC, and I was happy when I see Boost in the list, it is my dream and it will be honor to contribute to such a powerful library. Since I am good at algorithm and data structure, knowing that there are some idea projects relative with algorithm and data structure, like radix sort, trie, I want to know something detail about the plan to develop algorithm and data structure. Thanks, I am expecting to receive some useful replies.

4 6

Re: [boost] [config][mpl][type_traits][integer] BOOST_STATIC_CONSTANT should use constexpr
by Vicente J. Botet Escriba 20 Apr '13

20 Apr '13

Le 20/04/13 14:33, Vicente J. Botet Escriba a écrit : > Le 20/04/13 13:18, Antony Polukhin a écrit : >> 2013/4/20 John Maddock<boost.regex(a)virgin.net>: >> <...> >>> No that's correct as is: >>> >>> * if BOOST_NO_INCLASS_MEMBER_INITIALIZATION is defined, then the constant is >>> really an enum and there should be no out-of-line definitions. >>> * if BOOST_NO_INCLASS_MEMBER_INITIALIZATION is *not* defined, then the >>> constant *should* have the out-of-line definition in case it's address is >>> taken/used. >> Oh, now I see, thanks. >> >>> As for the original question, this is such a pervasive breaking change, I >>> think a new macro is inevitable I'm afraid :-( >> New macro will do exactly what the old macro did, but using C++11 >> feature. Code in all Boost libraries will be changed to use new macro. >> So the old macro will be required only for users code that use macro >> and attempts to take address of constant... >> >> To me, it looks less obscuring to have one macro and a note for users >> to use BOOST_CONSTEXPR_OR_CONST for out-of-line definition; than two >> macro (which one shall be used by default?) that do the same thing but >> very slightly differ in details. >> > Just to add some information about some uses > > grep -r BOOST_NO_INCLASS_MEMBER_INITIALIZATION * | wc -l > 113 > grep -r BOOST_STATIC_CONST * | wc -l > 6598 > The figures are a little bit better :) grep -r BOOST_STATIC_CONSTANT * | grep -v svn | wc -l 3030 grep -r BOOST_NO_INCLASS_MEMBER_INITIALIZATION * | grep -v svn | wc -l 57 Best, Vicente

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Trac: Add ref library
by Vicente J. Botet Escriba 20 Apr '13

20 Apr '13

Hi, Boost.Ref is not included as a library on the Trac system. Coul dit be added? Best, Vicente

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[log] Permission to merge to trunk
by Andrey Semashev 20 Apr '13

20 Apr '13

Hi, I'd like to ask for permission to merge Boost.Log v2 to Boost trunk. The library has passed the review back in 2010 and was provisionally accepted [1]. It has been reworked since then, and in a few recent posts I described the changes [2][3]. [1] http://lists.boost.org/boost-announce/2010/03/0256.php [2] http://thread.gmane.org/gmane.comp.lib.boost.devel/237748 [3] http://thread.gmane.org/gmane.comp.lib.boost.devel/239313

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Google Summer of Code - 2013: Boost C++ Libraries
by Ketan Akade 20 Apr '13

20 Apr '13

Hi, I am Ketan Akade, Graduate student at University of Southern California. I am majoring in Computer Science. I went through the project ideas of Boost C++ Libraries, and would like to work on it. I am particularly interested in the *Boost.uBLAS* project idea which is unifying representation of vector and matrices into a unique matrix class. Could you please let me know further details of the same? What steps should I take to start on this? PFA project proposal in which I have mentioned my academic and technical background. Thanks and regards, Ketan Akade Graduate Student, University of Southern California.

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[gsoc 2013] chrono::date
by Anurag Kalia 19 Apr '13

19 Apr '13

I saw the chrono::date library proposal in the ideas page of gsoc 2013. It already seems quite solid and fleshed out; I am confident that I have understood it and can carry it out. Here it is for reference: <http://tinyurl.com/ct4tc3m> I have a few questions though. 1) Is this proposal in its final stages? The Boost chrono library docs mention in appendices that they intend to implement it in later releases. What I want to ask is if I am allowed to propose changes in the library if I want to. For example, the proposal proposes that adding a year to 'Feb 29' (leap year) should result in 'Feb 28 of next year' (non-leap year). I tend to think this is counter-intuitive. The author already gives the excellent idea of using a syntax like "last/february/2013" which also covers the case of anniversaries falling on 'Feb 29' pretty well. Moreover, it is a pretty big assumption that a person would want to celebrate the 'Feb 29' anniversaries on 'Feb 28' and not on 'Mar 1'. Moreover, adding a month to '31 January' results in an invalid date (31 February). Why shouldn't we mirror the behaviour for years? We can just make a library function to cover this issue. In short, am I allowed to propose such changes? 2) How should I apply for gsoc now that I have found my area of interest? What is the last date of application? Shall I post a draft of my application here first for review before submitting it officially? Am I allowed to? 3) I have my final examinations scheduled during three weeks in the coming month of May after which I am totally free to pursue gsoc internship. Though I will use this time to research for design and implementations of other similar libraries, I would still need to channel much time into my examinations. How am I supposed to circumvent this conflict, given that I do have ample time to dedicate to my internship later on? Thanks.Anurag.

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[fusion] [range] Interest in unified functions
by Antony Polukhin 19 Apr '13

19 Apr '13

Hi, I was playing with Boost.Fusion and wrote this simple function: template <class Sequence> std::string stringize(const Sequence& seq) { std::string result; boost::fusion::for_each(seq, stringize_functor(result)); return result; } Which allows to convert many types to strings: boost::fusion::vector<cat, int, std::string> tup1(cat(), 0, "_0"); boost::tuple<cat, int, std::string> tup2(cat(), 0, "_0"); std::pair<cat, cat> cats; std::cout << stringize(tup1) << '\n' << stringize(tup2) << '\n' << stringize(cats) << '\n' But this example fails to convert the following : std::vector<cat> too_many_cats(20); All we need to do to allow conversions, is just add the following: #include <boost/range/algorithm/for_each.hpp> namespace boost { namespace fusion { template <typename Sequence, typename F> inline typename disable_if< traits::is_sequence<Sequence> , void >::type for_each(Sequence const& seq, F const& f) { ::boost::range::for_each(seq, f); } }} So now std::cout << stringize(too_many_cats) << '\n'; works and boost::fusion::for_each may work with any type, runtime length or compile time. We may also make a lot of other algorithms to make no difference between runtime and compile time classes: accumulate, find, find_if, count, all, none, begin, end, advance, distance, dereference, empty and others... The questions are: Is there interest in such features? Is there interest in adopting other algorithms and which ones? To what library shall those methods belong? -- Best regards, Antony Polukhin

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[signals2] Uncombined signal
by Ivan Le Lann 19 Apr '13

19 Apr '13

Hi, I have a project where I use boost::signals2 in the spirit of the "Signal Return Values (Advanced)" section of the tutorial. That is, I have signals roughly equivalent to : boost::signals2::signal<float (), maximum<float> > sig; // slots produce values accumulated by the combiner Problem comes when I want multiple combiners on the same slots. Especially combiners of different types : You need to duplicate signals, and you need your connection setup code to know about used combiners. IMHO, having a basic signal class with no combiner makes sense. Attached is a POC patch to version 1.50, to add to boost::signals2::signal the method : slot_call_range all (BOOST_SIGNALS2_SIGNATURE_FULL_ARGS(BOOST_SIGNALS2_NUM_ARGS)) const (in boost/signals2/detail/signal_template.hpp) >From there, I think one could use any algorithm/accumulator directly on the signal.all() result. Implementation left aside, any feedback on this ? Regards, Ivan

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GSoC project idea: Directory monitor for Boost.Asio (student wanted)
by Boris Schaeling 18 Apr '13

18 Apr '13

Here's another idea for a GSoC project: Turn the directory monitor from <http://www.highscore.de/boost/dir_monitor.zip> into a full-featured Boost.Asio extension. This includes understanding the source code of the existing directory monitor, getting familiar with Boost.Asio internals, enhancing the current interface, implementing the directory monitor on multiple operating systems, writing test cases and a documentation. This is a project which can be completed within a summer. It could be the right project for a student who is interested in Boost.Asio and wants to go through all steps from designing to documenting. Boris

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bug in boost::container ??
by Olaf Peter 18 Apr '13

18 Apr '13

Hi, the attached example confuses me, I've got: $ g++ -Wall boost_container_bug.cpp -o boost_container_bug && ./boost_container_bug (size=4 [1, 2, 3, 4, 0, 4]) $ LANG=en g++ --version g++ (GCC) 4.6.3 20120306 (Red Hat 4.6.3-2) Copyright (C) 2011 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Did I miss something or is it a bug? Thanks, Olaf

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[variant] Multivisitation patch
by Antony Polukhin 18 Apr '13

18 Apr '13

Hi, There is a ticket #8459 that adds boost::apply_visitor for arbitrary amount of arguments. If there will be no objections and comments, I'll commit it to trunk at the end of next week. -- Best regards, Antony Polukhin

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Using both boost 64 and 32 bit on Windows with CMake
by Klaim - Joël Lamotte 18 Apr '13

18 Apr '13

It appear that this mailing list don't accept cross messages so I'm posting a link to a discussion related to both boost and cmake. Basically I'm looking for guidance to help improving development of one application using boost in 64 and 32 bit modes by finding a way to make the FindBoost cmake module find the right binaries depending on either mode. Currently you have to specify an undocumented CMake variable manually to do this. See the full discussion: http://cmake.3232098.n2.nabble.com/boost-b2-Differenciate-32bit-and-64-bit-… Joel Lamotte

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Interested in working on a project for Boost
by Ganesh Prasad 18 Apr '13

18 Apr '13

I am a Student of 2nd Semester, B.Tech in Computer Science and Engineering from National Institute of Technology, Rourkela, India. I am interested in working on a project on “ Developing Data Structures and related algorithms for a generalized Matrix and Vector Class” for the Boost Libraries as a participant of GSoC. I have some experience in working on algorithm development in C++. And I am positive that I have pretty good knowledge in advanced C/C++.I have participated in various coding contests too. Though I am just a student of Second Semester, I can assure you that I'll be working up to the requirements and expectations. But I am new to this GSoC program. I need advice and help to go on with this project. So, requesting advice and help before I start discussing about my project ideas. :) -Ganesh Prasad

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[range] location of numeric algorithms
by Nathan Ridge 18 Apr '13

18 Apr '13

Hi, Is there any reason the numeric algorithms in Boost.Range (accumulate(), inner_product(), etc.) are located in boost/range/numeric.hpp rather than in files named boost/range/algorithm/<algorithm-name>.hpp like every other algorithm? I think it's confusing for users who expect the uniform file naming convention that Boost.Range applies to other algorithms, to apply to these ones too. Thanks, Nate

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[iostreams] Doc errors
by Richard Hadsell 18 Apr '13

18 Apr '13

I'm just starting to read the Boost.Iostreams documentation and found a couple of minor errors. Perhaps someone would like to make these trivial corrections to help other novices in the future. (1) 2.1.4. In the implementation of container_device::write, the block that writes remaining characters at the end of the container ("if (result < n) { ... }") should insert characters from 's + result', not from 's': "container_.insert(container_.end(), s + result, s + n);". (2) 2.1.4. In the implementation of container_device::seek, there are 3 uses of "ios_bas" instead of "ios_base". -- Dick Hadsell 203-992-6320 Fax: 203-992-6001 Reply-to: hadsell(a)blueskystudios.com Blue Sky Studioshttp://www.blueskystudios.com 1 American Lane, Greenwich, CT 06831-2560 Follow Blue Sky Studios on Facebook <http://www.facebook.com/BlueSkyStudios> and Twitter <http://twitter.com/#%21/blueskystudios>

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GOOGLE sUMMER OF CODE
by kashish jajodia 17 Apr '13

17 Apr '13

Dear sir/ma'am, I am really interested in your project(making libraries for C++) mentioned in google summer of code . I am good in algorithm and acquainted well with c++. What else do you require me to know for being a favourable candidate for this project??? & Do you Have any website/blog where I can get to know about the Boost libraries were included in C++11 standard library Thank you Yours kashish Jajodia B.tech computer science and engineering(second year) National Institute of technology , Trichy India

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About
by Hasit Bhatt 17 Apr '13

17 Apr '13

I am 3rd year student of Computer Science and Engineering from Institute Of Technology, Nirma University, Ahmedabad, one of the best Engineering colleges in Gujarat. I was going through GSoC ideas page and, as I like algorithms, I wish to work on algorithms. So, I just wanted to ask, how can I start working on it. ~ Hasit Bhatt

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