October 2009 - Boost - lists.preview.boost.org

C# LINQ-like library: Boost.Qlang.
by Germán Diago 16 Oct '09

16 Oct '09

IMPORTANT: Sorry I forgot to attach the code. This is the correct mail, ignore the other one. Hello. I'm working on a library that is very early in its development, but I wanted to share it to get some feedback and to know if someone would be interested in it. I have named the library Boost.Qlang, and, over the time, maybe I could launch it. Now about the library. Boost.Qlang is a library inspired in C#'s linq extensions. For now, as this is an early prototype, Boost.Qlang is implemented ONLY for c++0x making use of lambdas and variadic templates. The plan is to make it compatible with c++98 , but as I'm not very familiar with Boost.Preprocessor library, I sticked to c++0x to test the ideas. Now for the library, by example. The library uses this struct (for testing) and this vector: struct Person { std::string name_; std::string surname_; int age_; public: Person(const std::string & name, const std::string & surname, int age) : name_(name), surname_(surname), age_(age) {} }; vector<Person> persons = { {"German", "Gallardone", 23}, {"Pedro", "Ruiz", 28}, {"Hilario", "Pinose", 34}, {"Manolito", "Gafotas", 29}, {"Tomas", "Todonte", 56}, {"Tomas", "Ruiz", 33}}; Example 1: auto query = from(persons).where([](const Person & d) { return d.surname_ == "Ruiz"; }). select(full_object); What does this do? It selects Persons with surname "Ruiz". The full_object in select is a placeholder that selects the full object. The query is NOT executed, instead, a select_<...> object is returned, which represents a query. A query models the Range concept, so if you want to evaluate the query, you can do it like this: for (auto it = query.begin(); it != query.end(); ++it) cout << person.surname_ << std::endl; Any struct can be used for queries without any kind of adaptation. The original range cannot be modified through the query. Everything returned is a new object. If you want to evaluate immediatly the query and store it, to_list() and to_vector() can be used from the query object: vector<Person> vec = query.to_vector(); Example 2. Selecting a subset of the fields in Person. Sometimes we want to select just a subset of the fields in a query. This is done like this: auto query2 = from(persons).where([](const Person & d) { return d.surname_ == "Ruiz"; }). select(&Person::surname_); The query returns elements of type boost::tuple<std::string> containing the surname. Maybe in the future a specialized tuple will be returned, in order to access the elements in a readable way, maybe something like: get<&Doctor::surname>(elem); For now just a field can be selected at the same time in select, but the plan is to be able to select as many as necessary. There are also plans to be able to use as placeholders in select unary member functions (for now it's just pointer to member data) and lambdas. For example something like this could be done: auto myquery = from(persons).where([](const Person & d) { return d.surname == "Ruiz";}). select([](const Person & p) { return std::string(p.name_ + " " + p.surname_; }); The return type would be that of the lambda. Example 3. Nested queries: auto query3 = from(query).where([](const Person & a) { return a.age_ == 28; }). select(&Person::name_); This query holds an object with a subquery inside it. You can traverse the query and will get the expected results. For now the library, in theory, can use any class that models the range concept in the from clause. The plan would be to add xml access (I don't know much about xml, though) and for databases and so on, to get a uniform interface for data access for every single data source you can imagine. The library has been tested with gcc svn, which includes lambdas. There is a file attached to this mail with a qlangtest.cpp file in the qlang folder. The boost folder contains all the implementation. Feedback is very welcome.

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Is there a web site?
by gmane 16 Oct '09

16 Oct '09

That can answer the question of "What's new or changed in 1.41?" before the 1.41 beta comes out? Thanks

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[1.41] Build files locations, try 3
by Vladimir Prus 15 Oct '09

15 Oct '09

Some time ago, I have raised the concern that CMakeList.txt files violate directory structure requirements. See: http://thread.gmane.org/gmane.comp.lib.boost.devel/189496/ I have pinged this a few times, see: http://permalink.gmane.org/gmane.comp.lib.boost.devel/193415 to no response. Now, with 1.41 going out soon, can we finally solve this issue? To rehash, the options we have are: 1. Move Jamfiles to the top-level directory of each lib 2. Move CMakeList.txt files to the build subdir 3. Adjust library guidelines. 4. Remove library guidelines, since they seem to be ignored. I hope we don't end up with option 4, of course. Thanks, Volodya

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How to get the size of an C-array?
by vicente.botet 15 Oct '09

15 Oct '09

Hi, On TBoost.STM, I need to do something before deleting an array on each one of the elements of the array, or more precissely with the address of each one of the elements. T* ptr = new T[3]; // in another file, the number of elements to which ptr points is unknown. // before deleting for (size_t i=0; i< 'ptr size'; ++i) { // do something with &ptr[i] } delete [] ptr; As the number of elemenst is unknow in the separated unit, I have no mean to iterate on ptr to get the address of the elements. The C++ compiler or the C++ standard library knows this number of elements as it needs to call the destructor of each element when deleting the pointer. Is there something in Boost or a portable way to recover the number of elements of the array, maybe overloading the new [] operator and prefixing the allocate storage with some information? But what information can be stored so the implementation is portable? Any hint is welcome. Best, _____________________ Vicente Juan Botet Escribá

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Re: [boost] [1.41] boost-cmake leaving svn
by pete＠pcbartlett.com 15 Oct '09

15 Oct '09

On Thu 15/10/09 07:00 , "troy d. straszheim" wrote: Eric Niebler wrote: > > Not only is it disruptive, but it's against policy to commit directly > to release. I know that, I was just trying to spin it. > My opinion: the cmake build system should be like other parts of > boost: polished, documented, tested, reviewed, accepted, merged to > trunk and then to release, and actively maintained. Please forgive me for saying this is a bit far-fetched. If I propose a library for inclusion and it gets rejected, fine, I still have a library. If I propose a build system (arguably more work than a typical library) and it gets rejected, I've got nothing. A new library doesn't typically require everybody to change the way they do business throughout the entire release cycle, from development to testing, and therefore doesn't encounter the inertia of the community. For that matter, I'm having trouble imagining how one would merge a build system from trunk to release. This is the same problem that provoked this discussion. > Distributing an experimental build system in an official boost > release was probably a mistake. Well we thought we would get some users, and we got lots of them on the end-users' side, but it didn't catch on with boost developers as I'd hoped. C'est la vie. I think the better way is: * A few notes in Getting Started with pointers to the cmake stuff * One root CMakeLists.txt that just prints a message on where to get boost-cmake * A link to some boost-cmake tarball area alongside the standard boost tarballs. That's the new proposal. > In that light, I must reluctantly agree that removing cmake from > trunk and release is probably the right thing. Beman? I doubt that it is necessary to agree at this point. That stuff either comes out of release or goes out broken. > My worry is that as a side project, the cmake build system will get > less use and less attention. It's been 2 years since the cmake effort > began, and where are we? I don't see it that way. We have 115 people on the boost-cmake list, and a bunch of them were really helpful (thanks guys) in tuning up the build for 1.40.0, and we'll do it again in a few weeks for 1.41.0. Participation has been signficantly wider than when it was just Doug and I. There are docs, happy users, all that stuff. > I *really* want our users to have a standard option for building > boost that integrates well with their chosen build environment. They've got that. It's done. -t _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost Links: ------ [1] http://lists.boost.org/mailman/listinfo.cgi/boost

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[graph] Include conflict when using spirit classic and graph libraries together
by Oliver Koenig 15 Oct '09

15 Oct '09

Hello, boost/graph/depth_first_search.hpp includes boost/spirit/home/phoenix.hpp. This include points to Phoenix2, what finally leads to conflicts if the spirit classic library (using Phoenix1) is used together with the Boost graph library. Is the spirit include in boost/graph/depth_first_search.hpp needed at all? I cannot see where something from phoenix is used in that header and in our code everything seems to work fine if I simply remove this include. Sincerely ok -- ---------------------------------------------------- Oliver Koenig EVEN - Evolutionary Engineering AG WWW : www.even-ag.ch ---------------------------------------------------- -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.

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[bind] bound object type introspection
by Gennadiy Rozental 14 Oct '09

14 Oct '09

Hi, Following the discussion on users list I came to conclusion it's impossible at the moment to deduce argument types of bound object passed to the function template. Is there any reason why this can't be added in the manner similar to the boost::function typedefs? Gennadiy

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math/tools/rational.hpp gcc 3.2 problem
by Ralf W. Grosse-Kunstleve 14 Oct '09

14 Oct '09

gcc 3.2 doesn't compile this code (works with gcc 3.3 and up): #include <boost/math/distributions.hpp> int main() { boost::math::students_t_distribution<double> dist(1.); dist.find_degrees_of_freedom(1.,2.,3.,4.,5.); return 0; } Reduced: template <unsigned N, class T, class V> inline V evaluate_polynomial(const T(&a)[N], const V& val) { return val * a[0] * static_cast<T>(N); } int main() { double a[3]; double val; double result = evaluate_polynomial(a, val); return static_cast<int>(result); } dbg2.cpp: In function `int main()': dbg2.cpp:12: no matching function for call to ` evaluate_polynomial(double[3], double&)' Does anyone have an idea for working around the problem? Ralf

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Formal Review Request: Generic Geometry Library (GGL).
by Barend Gehrels 14 Oct '09

14 Oct '09

Hi, We would like to ask for a formal review for the Generic Geometry Library (GGL). The GGL defines concepts for geometries and implements some algorithms on such geometries. GGL contains a dimension-agnostic, coordinate-system-agnostic and scalable kernel, based on concepts, meta-functions and tag-dispatching. On top of that kernel, algorithms are built: area, length, perimeter, centroid, convex hull, intersection (clipping), within (point in polygon), distance, envelope (bounding box), simplify, transform, convert, and more. The library is also designed to support high precision arithmetic numbers, such as GMP. GGL contains instantiable geometry classes, but library users can also use their own. Using registration macros or traits classes their geometries can be adapted to fulfil the GGL-concepts. The GGL might be used in all domains where geometry plays a role: mapping and GIS, gaming, computer graphics and widgets, robotics, astronomy... The core is designed to be as generic as possible and support those domains. However, for now the development has been mostly GIS-oriented. We propose the extension model, the same way as GIL also applies it. So we are going to help to organize development of GGL extensions, where an extension is (mostly) something more specific to domains like mentioned above. The proposed GGL has seen four previews, many discussions and many changes in design and implementation, based on those discussions. The last preview was in February '09. Since then the design of the library is stable and the library contains a variety of coherent functionality. So we feel that the library is matured enough for formal review. Therefore, I would like to request a formal review and the library placed into the review queue. It is put into the Boost.Sandbox: https://svn.boost.org/svn/boost/sandbox/ggl/formal_review_request We have a review manager. Regards, Barend Gehrels, Bruno Lalande, Mateusz Loskot

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[test] compile-fail tests with precise output
by Jean-Louis Leroy 14 Oct '09

14 Oct '09

I would like to create tests that check, not only that a file will not compile, but that the errors contain specific strings. More precisely, I want to make sure that wrong code fails on a MPL assertion and not deep inside the template instantiations. Is that feasible? Thanks, Jean-Louis

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[1.41.0] Beta planned for next week
by Beman Dawes 13 Oct '09

13 Oct '09

Looks like we are on schedule for a 1.41.0 beta next week. Now would be a good time for developers to: * Merge any stable changes from trunk to release. You can tell if there are unmerged trunk changes with the svn diff command, or use trunk/tools/release/unmerged.bat. * Check http://beta.boost.org/development/tests/release/developer/summary.html to make sure your library's tests are clean. Thanks, --Beman

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Name of namespace detail
by Mateusz Loskot 13 Oct '09

13 Oct '09

Hi, Inspired by Jean-Louis question about what to put to namespace detail, I would be interested learning about rationale of name of the namespace detail (sometimes details or impl too). Recently, I've participated in a very interesting discussion, on ACCU members mailing list, about prefixes and suffixes like Base or _base nad Impl or _impl, as misused, irrelevant and confusing, meaningless, etc. For example, how to properly name elements of PIMPL idiom and similar. During the discussion I suggested that 'detail' is a good name for namespace dedicated to implementation details being not a part of public interface of a component. I got answer that it as the same issues (it's meaningless) as Impl etc. It raised some questions for myself, being interested in improving my craft, I would like to learn better about the name of namespace detail. I use detail name myself. Any better names for bucket with implementation details? Best regards, -- Mateusz Loskot, http://mateusz.loskot.net Charter Member of OSGeo, http://osgeo.org

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[signals2] combiner + groups -> topmost only (missing code)
by Oliver Kowalke 13 Oct '09

13 Oct '09

Hello, I need a combiner which executes only the slots within the highest group. How to access to group in the combiner? What happens with the input iterators if signal::disconnect_all_slots() gest called within the combiner? someting like this: struct combiner { template< typename It > void operator( It i, It e) const { // iterate over slots // execute only slots of highest group } }; signal< void(), combiner, int, greater< int > > sig; sig.connect( 0, slot1); sig.connect( 1, slot2); sig(); // only slot2 gets called regards, Oliver -- Jetzt kostenlos herunterladen: Internet Explorer 8 und Mozilla Firefox 3.5 - sicherer, schneller und einfacher! http://portal.gmx.net/de/go/atbrowser

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Deciding what to put in `namespace detail`
by Jean-Louis Leroy 13 Oct '09

13 Oct '09

For my future Boost.RDB submission, I feel tempted to put everything except the names that are in the public (documented) interface in a nested `namespace detail`. Why not even put *everything* there and copy selected names in the public namespace by means of using-declarations. Has it been already done ? And what about having three namespaces : a "public" one for the user, a "protected" one for those extending the lib, and a "private" one for undocumented internals? Opinions and advise welcome... J-L

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Workaround request: boost::shared_ptr & Intel C++ Compiler
by Marat Abrarov 13 Oct '09

13 Oct '09

Hi! I wrote about my problem before (Boost-users Digest, Vol 2116, Issue 1: "boost::options, boost::shared_ptr with Intel C++ Compiler 11.x") but didn't received any response yet. So here's a copy: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I use boost 1.40. I have a project at http://sourceforge.net/projects/asio-samples/ (only SVN trunk is available now) It uses MS C++ Compiler (9.0 SP1 - MS Visual Studio 2008 SP1) and boost::program_options (+ boost::asio + boost::...). When I switched that project (I mean "echo_server") to Intel C++ Compiler 11.1.038 (I tried all 11.1.x) and built debug version (Debug Win32) (with addition of option /vmg to compiler command line - stupid Intel :) it works fine except shared_ptr-to-bool cast (for example: include/ma/echo/server/session_manager.hpp: 319). This issue I found only at "Debug Win32" build mode - at "Debug x64" all is fine and the built executable (echo_server.exe) works right. When I build "Release Win32" or "Release x64", the built executable don't work at all - it fails somewhere at the boost::program_options (I think at std::vector<std::string>::operator= or std::vector<std::string> copy-constructor). Does anybody: 1) tried to use boost::shared_ptr 2) tried to use boost::prorgam_options with Intel C++ Compiler 11.1.x? P.S. If I change boost_1_40_0\boost\smart_ptr\detail\operator_bool.hpp: 9 - add "|| defined (BOOST_INTEL)" - then shared_ptr-to-bool cast works fine (Win32/x64 Debug/Release) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Does anybody has similar problems with Intel C++ Compiler and boost::shared_ptr? Is anybody from boost community interested for Intel C++ Compiler support? Regards, Marat Abrarov.

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[signals2] combiner + groups -> topmost only
by Oliver Kowalke 12 Oct '09

12 Oct '09

Hello, I need a combiner which executes only the slots within the highest group. How to access to group in the combiner? What happens with the input iterators if signal::disconnect_all_slots() gest called within the combiner? someting like this: struct combiner { }; -- Neu: GMX DSL bis 50.000 kBit/s und 200,- Euro Startguthaben! http://portal.gmx.net/de/go/dsl02

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[rdb] 0.1.00 - prepared statements
by Jean-Louis Leroy 11 Oct '09

11 Oct '09

I have uploaded version 0.1.0 to the vault. It introduces prepared statements and placeholders. No doc on this yet but it's easy to use, e.g. BOOST_AUTO(st, db.prepare(insert_into(p)(p.id, p.first_name, p.name, p.age).values(_, _, _, _))); st.execute(3, "Bart", "Simpson", 9); st.execute(4, "Lisa", "Simpson", 7); st.execute(5, "Maggie", "Simpson", 0); It also works with update, delete and select. Placeholders are allowed in predicates as well. Parameters are type-safe, if they don't agree with the type of their corresponding placeholder (as deduced by the context in which it is used), you will get a compilation error. More examples in the test file here : http://code.google.com/p/boost-rdb/source/browse/libs/rdb/test/test_odbc.cpp J-L

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[wave] 1.40.0 build problem on recent intel
by troy d. straszheim 10 Oct '09

10 Oct '09

Over on the boost-cmake Justin Holewinski pointed out that wave doesn't build on recent intel compilers. Details and fix here: http://software.intel.com/en-us/articles/error-409-when-building-boost-libr… -t

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Re: [boost] threads: how to remotely kill a thread?
by David M. Cotter 10 Oct '09

10 Oct '09

yes i have seen the error of my ways, and am now using thread.interrupt () and i sprinkle interruption_point() in my inner loops of the thread thanks for the feedback. -dave On Oct 9, 2009, at 9:20 PM, Yigong Liu wrote: > It is kind of dangerous for one thread to kill another thread > forcefully or directly, since the 2nd thread may be in the middle of > holding a system resource or changing some state. Killing it may > left the system in corrupted state. better using "cooperative" > shutdown, the 1st thread sends the 2nd thread some notification, > either thru shared state or interrupt. For similar reasons, java > deprecated many thread api (http://java.sun.com/j2se/1.4.2/docs/guide/misc/threadPrimitiveDeprecation.h… > ). > > On Fri, Oct 2, 2009 at 9:16 AM, Andrey Semashev <andrey.semashev(a)gmail.com > > wrote: > David M. Cotter wrote: > say i'm on the main thread, and i've got a thread::id of some other > preemptive thread. i do not have the actual boost::thread object > any more. > > and i want to unceremoniously kill that thread. like right now. > > how do i kill it? i don't see a way to recover the actual > boost::thread from the thread::id. but even if i could, and then > call thread.interrupt(), that's more of a polite request which is > free to be ignored, rather than a you_must_die_now() thing. > > The main problem with killing threads is that it doesn't unwind the > stack and thus breaks RAII. Therefore the best "official" way to > terminate the thread in C++ is to interrupt it. If you want to do it > the hard way, you're in C world with pthread_kill and alikes.

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[fusion] accumulate vs. std::accumulate
by Christoph Heindl 10 Oct '09

10 Oct '09

Hi, I'm currently confronted with an issue raised before [1] on this list: boost::fusion::accumulate takes its arguments in reverse order compared to std::accumulate. The issue is still marked as 'new' on trac [2]. What are the chances to have this issue fixed for the next release? Kind regards, Christoph [1] http://lists.boost.org/Archives/boost/2008/09/142490.php [2] https://svn.boost.org/trac/boost/ticket/2355

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[trunk] Missing Jamfile in Boost Root Directory
by Dean Michael Berris 10 Oct '09

10 Oct '09

Hi everyone, I just did an SVN update to the latest in Boost's trunk and I don't see a Jamfile in the root directory anymore. I ask because I do this in my project Jamroot, which used to work: import os ; local BOOST_ROOT = [ os.environ BOOST_ROOT ] ; use-project /boost : $(BOOST_ROOT) ; But now when running bjam it complains that it can't see a Jamfile in the BOOST_ROOT directory. Any workarounds for this? TIA -- Dean Michael Berris blog.cplusplus-soup.com | twitter.com/mikhailberis linkedin.com/in/mikhailberis | facebook.com/dean.berris | deanberris.com

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[MPI?] which API should i use for this?
by David M. Cotter 10 Oct '09

10 Oct '09

I have a need to send an "event" to the "main thread's event loop". this may be done from a preemptive thread, a cooperative thread, a timer, or even the main thread itself. i want it to be posted into the event stream and handled in the order that events get processed on the main thread. would i use 'MPI'? or 'interprocess'? or is there a 'thread' way to do this? if it's MPI, what would be the right call? i'm coming from Mac land where i have traditionally used PostEventToQueue()

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[Boost.Units] non-integral unit exponents
by Belcourt, Kenneth 09 Oct '09

09 Oct '09

Hi, I'd like to use Boost.Units but am unsure whether I can declare a unit like this: W/m^2 Pa^0.25 K^1.523 In addition, I'd like the ability to change the pressure (Pa) and temperature (K) coefficients at runtime (user supplied input might change the default coefficients). Are these things possible with Boost.Units and, if so, could someone point me to an example? (I need this for nucleate boiling curves). Thanks. -- Noel

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threads: linking on OSX
by David M. Cotter 09 Oct '09

09 Oct '09

I followed the instructions from here: http://www.boost.org/doc/libs/1_40_0/more/getting_started/unix-variants.htm… and it spent a bunch of time compiling everything. no errors. yay. so then i go to link my program, i added <boost dir>/stage/lib/ libboost_thread.a to my project, cuz that's how you static link, right? where <boost dir> is the location of the boost installation but it says: <boost dir>/bin.v2/libs/thread/build/darwin-4.2.1/release/threading- multi/libboost_thread.dylib, file is not of required architecture Undefined symbols: <long list of all the boost symbols i used> interesting that even by adding the .a file, it went and found the dylib? is that normal? anyway, wrong architecture?? how do i make it build universal? (PPC plus intel? and what's with the missing symbols? i'm not really a n00b, i just appear to be one today.

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[parameter] Ticket #3114
by Jeremiah Willcock 09 Oct '09

09 Oct '09

Would it be possible to have the feature requested by ticket #3114 (https://svn.boost.org/trac/boost/ticket/3114) implemented? This would make the Boost.Parameter library much more useful for situations where default argument types do not always exist. Thank you. -- Jeremiah Willcock

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[Property map] 1.40.0 breaks boost.graph python bindings
by John Reid 09 Oct '09

09 Oct '09

I'm using gcc 4.2.4 on Ubuntu. The boost.graph python bindings (http://www.osl.iu.edu/~dgregor/bgl-python/) work fine with boost 1.39. When I try with boost 1.40 I get many errors such as the following: ./boost/graph/python/resizable_property_map.hpp:101: error: ‘class boost::vector_property_map< boost::default_color_type, boost::graph::python::basic_index_map< boost::graph::python::basic_descriptor<boost::detail::edge_desc_impl<boost::bidirectional_tag, void *>, boost::bidirectionalS>, boost::adj_list_edge_property_map< boost::bidirectional_tag, long unsigned int, const long unsigned int &, void *, const boost::property<boost::edge_index_t, long unsigned int, boost::no_property>, boost ::edge_index_t>>>’ has no member named ‘get_store’ Does anyone know what changed between 1.39 and 1.40 to break this? The Readme.txt that comes with boost 1.40 suggests that nothing was updated in the property map library. BTW it doesn't compile with gcc 4.3 either but then neither does it compile with boost 1.39 (albeit for different reasons). I can provide all of the error messages if needed. John.

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[1.41.0] Cleaning up inspection errors
by Beman Dawes 09 Oct '09

09 Oct '09

The Inspection Report is showing 1292 problems reported. I'd like to drive that number way lower for the 1.41.0 release. The "Worst Offenders" list is: test (254) regression (145) gil (140) build (116) proto (75) See http://boost.cowic.de/rc/inspect-trunk.html Developers, please fix any problems in your library. Thanks, --Beman

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[program-options] Ticket #1132, multitoken() and zero_token()
by Sascha Ochsenknecht 09 Oct '09

09 Oct '09

Hello, I would like to have an option which allows multi token but not multiple occurrences of the option or at least a way to distinguish the occurrences: E.g. something like: program.exe --option value1 value2 I tried the following: 1) desc.add_options()("option", value<string>()->multitoken(), "help"); With the above command line I get exception: multiple values not allowed 2) desc.add_options()("option", value<vector<string> >(), "help"); Command line is parsed without error but only value1 is stored in the vector -> ERROR, should report 3) desc.add_options()("option", value<vector<string> >()->multitoken(), "help"); Command line is parsed without error both values are stored in the vector, but program.exe --option value1 --option value2 and program.exe --option value1 value2 leads to the same vector contents. With the current version it isn't possible to distinguish to occurrences of a certain option and it is not possible to implement an option which has the multitoken attribute but isn't allowed to occur several times. I'm willing to work on a patch for this issue, but first I want to discuss how to solve this, i.e. how the library should behave. The problem is possibly that specifying a list or vector implies that an option can occur multiple times. I think maybe following solution could work: 1) desc.add_options()("option", value<vector<string> >(), "help"); multiple occurrences of the option are allowed and pushed to the vector but only one value per option occurrence (like it is implemented now) 2) desc.add_options()("option", value<vector<string> >()->multitoken(), "help"); multiple occurrences of the option are NOT allowed, the multiple tokens/values are pushed to the vector 3) desc.add_options()("option", value<vector<vector<string> > >()->multitoken(), "help"); multiple occurrences of the option are allowed, the multiple tokens/values are pushed to the inner vector E.g. program.exe --option value1 value2 --option value3 --option value4 value5 This would result in the following storage sheme: { { value1, value2 } { value3 } { value4 value5 } } I'm not sure if a could become a friend of this implementation ... but it would work at least. Another way would be to join the multitokens into a single string: { "value1 value2" "value3" "value4 value5" } .. but this I don't like :-(. What do you think? Thanks & regards, Sascha PS: Is somebody working on ticket #1132 ??

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[rdb] 0.11
by Jean-Louis Leroy 08 Oct '09

08 Oct '09

In this drop : * Everything related to SQL composition has been moved to namespace boost::rdb::odbc * Update syntax has changed, instead of .set().set() chains it is now closer to SQL syntax (an deasier to implement): update(p).set(p.id = 1, p.first_name = "Homer") * Qualified table names: person::qualified p; partner::qualified l; select(p.id).from(p, l).where(p.id == l.wife) gives: select person.id from person, partner where person.id = partner.wife * in predicate: select(p.id).from(p, l).where(p.id.in(select(l.husband).from(l))) select(p.id).from(p).where(p.id.in(p.age + 1, 2)) * NULL: insert_into(p)(p.id, p.age).values(1, null) update(p).set(p.age = null).where(p.id == 1) select(p.id).from(p).where(p.age == null) Whoa! This gives: select id from person where age is null I'm only 80% sure about this one. Like everybody I suppose I have tried one day to compare with NULL, only to realize that the result is always false. After a while, ahem...So I have implemented operator == to do the right thing. It could have been: select(p.id).from(p).where(p.age.is_null()) Does anyone has an example where it makes sense to truly compare (using =) with NULL ? As for returning the NULL indicator when reading results, I chose not to use Boost.Optional (although I will probably add support for optional as well) because: 1. it would cost one bool (most likely the size of an integer) per column 2. IMHO the automatic conversion to bool is a bad idea 3. the value inside an optional<> cannot be addressed Instead I have complemented a fusion::vector with a std::bitset. The tutorial shows how to use this. I am hesitating a bit about pushing fusion::vector inside the implementation (i.e. nullable<int, char...> instead of nullable< fusion::vector<int, char> >). * Result sets: execute(Select) now returns a ResultSet object that allows retrieval row by row: also see the tutorial here : http://yorel.be/boost/libs/rdb/doc/html/rdb/tutorial.html#retrieve_data There is also a "Jumbo select" at the bottom of the tutorial that recaps everything that is supported for the moment. J-L

5 10

[threads] wait() and signal() ?
by David M. Cotter 07 Oct '09

07 Oct '09

on the mac the notion of a semaphore is at a slightly higher level than a condition_variable. but it seems in boost::thread we must use the actual condition_variable. on the mac, with a semaphore, the value can be pre-set to signal, so that the next wait() is passed right thru, since the signal was sent ahead of time. eg: you could do this: Semaphore sem; // newly initialized semaphore, brand new, never waited upon sem.signal(); // you can pre-set the signal! // later in the code sem.wait(); // no wait, since signal was already sent // and later still sem.wait(); // now we wait in fact, actually, the way it actually happens on the mac is that a newly initialized semaphore comes IN WITH the semaphore pre-signaled. so you actually have to call wait() immediately to eat that signal. i've got lots of code that does this: Semaphore sem; sem.wait(); // eat the first signal i thought that was normal. trouble is,i've got lots of code that does NOT eat that first signal, depending on the first wait call to be passed thru immediately. this is the code that now breaks. in converting to boost::thread, there doesn't seem to be a way to pre- set the signal. or to reset the state of a semaphore from an unknown state to a known state, eg this code: sem.signal(); sem.signal(); sem.wait(); that guarantees that the next wait will actually wait, regardless of the state of the sem before hand. how can i do this with boost::thread ?

6 7

[rdb] Repository, contributing, copyright, etc
by Jean-Louis Leroy 07 Oct '09

07 Oct '09

* Respository I have set up a Mercurial repository for rdb. You can get a copy with this command: hg clone https://boost-rdb.googlecode.com/hg/ boost-rdb You can view the source without installing Mercurial at that URL. * Contributing For those who consider contributing: I would like to keep clear copyright on this work. I propose the following arrangement: if you send me a patch that touches any of my copyrighted files, and I decide to use it, then you agree to transfer the copyright on the entire patch content to me. In return, I guarantee: 1/ the files touched by the patch will remain available under the Boost license 2/ you will get credit for it in the "Acknowledgements" section of the doc. If you create a set of files that is independant from mine and wish to put it in the distributions or in the repository, then you retain the copyright on them and set the rules you want. What I have in mind here is a native binding to a database. I hope that by next year we will have native bindings for all the major databases and obviously I am not going to write them all by myself. * Please help I am looking for the sql 2003 syntax expressed as a graph, preferably available online. Books suggestions are welcome too. * Extensibility For a small touch of technical stuff in this mail: I am trying hard to make it easy to support the various dialects. Here is a proof of concept (add MySQL LIMIT clause): https://boost-rdb.googlecode.com/hg/libs/rdb/doc/examples.cpp J-L

1 0

[utility] auto_buffer v2
by Thorsten Ottosen 07 Oct '09

07 Oct '09

Dear All, Hereby an updated class. Thanks to all who contributed with comments to the first try. I have made the following changes: 1. push_back() overloads are now growing 2. added swap() (boy, was this nasty to implement). I assume the allocator can be wapped without throwing. How do other people copy with this problem? 3. added copy-constructor + copy-assignment 4. made the min capacity equal to N, the number of elements in the stack buffer 5. the size of the internal buffer is now controlled via two policies: template< unsigned N > struct store_n_objects; template< unsigned N > struct store_n_bytes; the default is store_n_objects<256>. The reason is that we don't want the capacity to change just because we compile on a different platform. 6. added comparison operators Comments most welcome! best regards -Thorsten

4 7

[asio] confused by multiple socket flavors
by Roland Schwarz 07 Oct '09

07 Oct '09

There is a stream_socket_service and a ip::tcp::socket class, with almost the same member functions. I do understand that the first "is_a" service while the second "has_a" service. Is there any rationale beyond just having both? When would I want to use which one? Do I have overlooked something in the documentaion? Any hints appreciated. Roland -- _________________________________________ _ _ | Roland Schwarz aka. speedsnail |_)(_ | sip:speedsnail@ekiga.net | \__) | mailto:roland.schwarz@chello.at ________| http://www.blackspace.at

1 0

custom async devices
by Roland Schwarz 07 Oct '09

07 Oct '09

Recently I had a question about how I could use asio for performing asynchroneous file IO. In the meantime I found that there are already some classes for doing async_read_at IO on handles, but only for windows. Since I need to address multiple platforms I am wondering how I would go about that. I am thinking of an emulation layer in user-space based on threads. I guess I could set up a thread-pool that will accept async call ins. The thread pool would know about an io_service and when a task, e.g. a file IO has completed, use the post function on the io_service to invoke the completion handler. Is this a reasonable design? Any pros/cons? Does anyone know of an example that I could use as a starter? Thank you, Roland -- _________________________________________ _ _ | Roland Schwarz aka. speedsnail |_)(_ | sip:speedsnail@ekiga.net | \__) | mailto:roland.schwarz@chello.at ________| http://www.blackspace.at

1 0

how to mark test as "expected fail" for some toolsets
by Gunter Winkler 07 Oct '09

07 Oct '09

Hello, I'd like to mark the begin_end test of uBLAS as compile-fail for MSVC 7.1 ([1]). However I was not able to figure out how this works. Does anyone have some insights (or maybe a patch) to do this? [1] http://www.boost.org/development/tests/trunk/developer/output/daw-msvc71-bo… mfg Gunter

3 3

Bjam outside Boost tree
by Jean-Louis Leroy 06 Oct '09

06 Oct '09

I am working on a lib that is laid out in typical boost fashion: a directory with boost/rdb/includes.hpp, libs/rdb/src/stuff.cpp. When I put these two directories right inside a Boost tree that builds properly with bjam, I can build my libs as well (via chdir to libs/rdb/test and run bjam). I managed to get that much working. Now I would like to build outside the boost tree. I have found this message:http://lists.boost.org/boost-build/2002/11/2221.php but the link it contains is broken. I have tried to locate the information in the doc for half an hour now, without success. I tried to set BOOST_BUILD_PATH AND BOOST_ROOT to point to the boost tree. And copied boost-build.jam to the root of my dir. Can someone help me with this please? TIA, J-L

3 14

simple range adapter
by Neal Becker 06 Oct '09

06 Oct '09

I'd be surprised if others haven't needed this. While range comes with an adapter for plain old C array, it doesn't come with an adapter from that other (probably more common!) kind of plain old C array: a pointer and length. This seems useful. Maybe add to examples?

3 6

svn.boost.org has invalid ssl certifcate
by Markus Werle 06 Oct '09

06 Oct '09

Hi! Maybe this is only an issue with paranoid or misocnfigured firefox, but annoying anyway, since I change platforms very often. firefox reports: svn.boost.org uses an invalid security certificate. The certificate is not trusted because the issuer certificate is unknown. (Error code: sec_error_unknown_issuer) Can this be fixed on the server side? best regards, Markus

4 3

[Variant]
by Cosimo Calabrese 06 Oct '09

06 Oct '09

Hi to all, I've looked at the following example: http://www.boost.org/doc/libs/1_40_0/doc/html/variant.html#variant.motivati… and I think that miss an include: #include <string> Best regards, Cosimo Calabrese.

2 1

Off-topic question about Boost trac
by Mateusz Loskot 05 Oct '09

05 Oct '09

Hi, First, forgive me I'm sending this off-topic question to the mailing list, but I'm actually not sure where it would belong. Probably, I should direct my question to Boost Trac admins, but I don't know how to reach them. So, here we go: I'm involved in OSGeo Foundation and we maintain number of Trac instances (http://trac.osgeo.org/) for our projects. For longer while, we've been experiencing server load issues related to Trac. I noticed that Boost Trac displays "Server Load Average" information in below the menu bar. I would like to setup the same feature for OSGeo but I can not find any information how to do it. Could you tell me how you've got this for Boost Trac? Perhaps you could also tell me why you've decided to display this "Server Load Average" information in the Boost Trac? Does it mean Boost were experiencing load issues? Thanks for your help! Best regards, -- Mateusz Loskot, http://mateusz.loskot.net Charter Member of OSGeo, http://osgeo.org

1 0

[task] reschedule_until
by Baxter Jeremy 05 Oct '09

05 Oct '09

> Date: Fri, 2 Oct 2009 18:59:10 +0200 > From: k-oli(a)gmx.de > Subject: Re: [boost] [task] > > Second - I'm finishing boost.task-0.4.0 which replaces > this_task::reschedule_until() by this_task::block(). > block() suspends the current task without blocking the > worker-thread. The > blocked task gets rescheduled by the internal scheduler > (returning from > block()): > > while ( ! condition) > this_task::block(); > > Version 0.4.0 allows to synchronize or exchange messages > between the tasks > without deadlocking the threadpool (that means amount of > tasks >> worker- > threads in pool). > > regards, > Oliver Thanks - I'll steer clear of using reschedule_until at the moment. Being able to block a task without locking out the worker thread would be useful for me, but I suspect my requirement may be rather different to yours. I'm pretty much assuming amount of tasks == worker-threads in pool. My main interest in a thread pool is to avoid creating and destroying a new thread each time a task has to run but I suspect I may use task or threadpool it this way initially and see what the overhead is like. Jeremy The information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). The information in this communication may be confidential and/or legally privileged. Nothing in this e-mail is intended to conclude a contract on behalf of QinetiQ or make QinetiQ subject to any other legally binding commitments, unless the e-mail contains an express statement to the contrary or incorporates a formal Purchase Order. For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful. Emails and other electronic communication with QinetiQ may be monitored and recorded for business purposes including security, audit and archival purposes. Any response to this email indicates consent to this. Telephone calls to QinetiQ may be monitored or recorded for quality control, security and other business purposes. QinetiQ Limited Registered in England & Wales: Company Number:3796233 Registered office: 85 Buckingham Gate, London SW1E 6PD, United Kingdom Trading address: Cody Technology Park, Cody Building, Ively Road, Farnborough, Hampshire, GU14 0LX, United Kingdom http://www.qinetiq.com/home/notices/legal.html

2 1

[task] reschedule_until
by Baxter Jeremy 05 Oct '09

05 Oct '09

- my example and some of Vicente's comment snipped - > > I think that it will not to much complex to provide a > function that submit a task that must run on the context of a > different thread. Would this kind of submit function help you? > I'm not sure that it would help, I think that I could construct a more complex example with more tasks and threads that would still deadlock. In general I think it ought to be a requirement that the threadpool works if it has only a single thread (in which case the above would not work). > > I'm not sure that there is a general solution to this > problem without > > using more threads so that any potentially runnable task will get a > > chance. > > You are right this should be a deadlock problem with the > current implementation. > I don't think however that having more threads would solve > the issue, but just reduce its frequency, as the issue > appears when tasks T1 and T2 are handled on the same thread. > I agree, that is why I was not keen on reschedule-until. If blocking is used I think an unexpected deadlock could occur unless all blocked tasks can be resumed in any order, not strictly in reverse order of their reschedule calls as in the current implementation. > In order to avoid the issue we need to avoid two blocking > tasks to be executed on the same thread. The user should state > blocking task on the submit function. The scheduler will not > take a blocking task while in the reschedule_until function. > Of course, in order to be able to avoid any deadlock > associated to the fact we are using a thread pool, the number > of threads must grow, if there is no free worker threads able > to handle the new blocking task. The reschedule_until > function should throw an exception when the task is not a > blocking task. > > This should solve the issue, but introduce a burden at the > user level, i.e. specify if the task can block or not. > > Jeremy, Oliver, what do you think? > > Best, > Vicente > > I think Oliver's intention to use a fiber style scheduler is the right one. To avoid problems all possible mechanisms of blocking would need to be considered and protected against and the temptation would be to declare most tasks as blocking. Even if tasks don't block they may run on the thread for a long time before returning. A dynamic thread pool would also be a solution, starting more threads as tasks block and cleaning them up when the queue is empty. This is the approach used in the Java Executors class (http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/Executors. html). I'm not sure if there is a way to detect the difference between threads being busy and being blocked as in general you would like to keep the number of unblocked threads down to the number of cores. Jeremy Jeremy Baxter Lead Researcher, UAVs & Autonomy Tel: 01684 894801 email: jwbaxter(a)QinetiQ.com www.QinetiQ.com QinetiQ - Delivering customer focused solutions Please consider the environment before printing this email. The information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). The information in this communication may be confidential and/or legally privileged. Nothing in this e-mail is intended to conclude a contract on behalf of QinetiQ or make QinetiQ subject to any other legally binding commitments, unless the e-mail contains an express statement to the contrary or incorporates a formal Purchase Order. For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful. Emails and other electronic communication with QinetiQ may be monitored and recorded for business purposes including security, audit and archival purposes. Any response to this email indicates consent to this. Telephone calls to QinetiQ may be monitored or recorded for quality control, security and other business purposes. QinetiQ Limited Registered in England & Wales: Company Number:3796233 Registered office: 85 Buckingham Gate, London SW1E 6PD, United Kingdom Trading address: Cody Technology Park, Cody Building, Ively Road, Farnborough, Hampshire, GU14 0LX, United Kingdom http://www.qinetiq.com/home/notices/legal.html

2 1

Re: [boost] [rdb] rdb/persistent integration
by strasser＠uni-bremen.de 05 Oct '09

05 Oct '09

>> also, you could use more than one resource managers at a time, so you could >> have distributed transactions between two databases, between a file and a >> database, etc., and can have references across resources. (a locator can >> reference an object in any resource, and can be stored as part of an object) >> > Very interesting project. At this point my feeling is that there is room > to slip not one but two of my libs under yours ! > what`s the other library? btw, I wasn`t suggesting we should merge our libraries. a stand-alone sql db layer definitely makes sense. even a standalone o-r mapper might make sense, depending on what kind of user interface you planned for it. it might e.g. be better for some use cases to give the user more control over when and how actual SQL is produced and objects are stored than my library does. much like my resource manager uses Boost.Serialization, but doesn`t replace Boost.Serialization. remember that my intent was a user interface as close as possible to using regular objects in memory, so there is no "store this object now" function. the resource manager is free to cache and postpone accesses to the storage engine, as long as it guarantees that the object is stored on transaction::commit the latest. but we should work together on "linking" the libraries, i.e. implementing a boost.persistent resource manager that uses your o-r mapper, in the current design. or merge your o-r mapper library with my library, but leave the sql db layer a seperate library. depending on the o-r mapper interface you planned.

1 0

Looking for a name for a Subjet-Entity-Role library
by vicente.botet 05 Oct '09

05 Oct '09

Hi, I'm developing a library based on the Object Role pattern. The library use the following concepts: Entity, Role, Subject, Cloture. Its main goal is to help on subjetive programming. I was started to name this library SER (for Subject-Entity-Role). Next follows some Entity-Role-Subject declarations class Person : public entity<Person> {...}; template <typename Base> class PersonRoleTmpl : public basic_role<Person, Base> {...}; class PersonRole : public PersonRoleTmpl<> {...};class Employee : public role<Employee,PersonRole> {...}; class Salesman : public Employee {...}; class Developer : public Employee {...}; class Manager : public Employee {...}; class Guarantor : public role<Customer, PersonRole> {...}; class Customer : public role<Customer, PersonRoleTmpl<entity<Customer> > > {...}; class CustomerRole : public basic_role<Customer> {...}; class Borrower : public role<Borrower, CustomerRole> {...}; class Investor : public role<Investor, CustomerRole> {...}; class CustomerAndEmployee : public subject<Person, roles<Customer,Employee> > { ... }; Any sugestions for the name of the library, 'Subjetive', 'SER'? Best, _____________________ Vicente Juan Botet Escribá

5 7

[sandbox] Mysterious (?) commit messages, 'm', 'a', 'd'
by Niels Dekker - address until 2010-10-10 04 Oct '09

04 Oct '09

There appear commit messages of a single letter: 'd', 'm', 'M', 'a'. Or combined: "m/a". It seems like they only appear in the sandbox. https://svn.boost.org/trac/boost/timeline What do they mean? (Maybe "e_r" can tell us.) FWIW, I'd rather see more "human friendly" commit messages. Thanks in advance, Niels -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center

2 1

GIL extensions home and guide
by Mateusz Loskot 04 Oct '09

04 Oct '09

Hi, May I ask for update where is most current home for Boost/Adobe GIL library extensions [0]? What's the difference beetween extensions in Boost SVN [1] and those hosted in Google Code [2] ? Second, what document should one refer to learn about developing new I/O extensions for GIL? The GIL Design Guide [3] is quite dated, from 2007 [0] http://opensource.adobe.com/wiki/display/gil/Contribute+to+GIL [1] https://svn.boost.org/trac/boost/browser/trunk/boost/gil/extension/ [2] http://code.google.com/p/gil-contributions/ [3] http://www.boost.org/doc/libs/1_40_0/libs/gil/doc/html/gildesignguide.html Best regards, -- Mateusz Loskot, http://mateusz.loskot.net Charter Member of OSGeo, http://osgeo.org

2 2

[rdb] 0.0.09
by Jean-Louis Leroy 04 Oct '09

04 Oct '09

In this version : * EXISTS * consistency check in INSERT...SELECT * DISTINCT, ALL * transactions The transaction stuff is pellicular. It simply maps to vendor calls. I am hesitating a bit, either make a common interface for the most common operations (like execute) directly in each backend (aside with vendor-specifc calls) or put them in a separate wrapper or even decide that it's not in the scope. There's more redesign in the select from which I think I can get an elegant implementation of vendor-specific features (like LIMIT). The idea is to pass all the data in a fusion map, allowing vendor specific parts of the statement to slip their own data inside it. In fact this also is how DISTINCT works. I dropped the composition of lists via chained calls to operator (). It's all preprocessor-based now. The () chain system was limited by FUSION_MAX_VECTOR_SIZE anyway. I have installed MySQL on my computer. I am still accessing it via ODBC but I'll probably start the native support soon. Yesterday I tried to upload and just when I pushed the upload button the vault server crashed. I suspect that it was my upload that triggered it. J-L

6 15

[trac] Make me property_tree owner
by Sebastian Redl 04 Oct '09

04 Oct '09

Hi, Could somebody who has the authority to do so please make me (cornedbee) the owner of property_tree? Currently, all PTree tickets are still assigned to kaalus, who is the original author. Sebastian

2 1

[Fusion] port to c++0x
by Christopher Schmidt 04 Oct '09

04 Oct '09

I participated in Google's 'Summer of Code' for Boost this year. My project was to port Boost.Fusion to c++0x. The program is over now and I would like to give you a short report on my work and put my code up for comments. In a nutshell, there is rvalue support, native variadic templates are used if possible and the public classes and (meta-) functions are guarded by a set of static asserts that detect most invalid (template) arguments. I also added certain new functionality to provide an easier, faster and more intuitive programming interface. My implementation is pretty much backwards compatible and all test cases pass on gcc 3.4/4.4 and vc 9. Here is a short overview of the most striking changes besides the implementation of raw c++0x support. I removed the deque container and the extension-classes. The deque container is undocumented and, in my opinion, does not go well with the other container due to its intrinsic extension mechanism. There also should not be a performance gain compared to a regular fusion::joint_view in combination with two fusion::vector. The extension classes are pretty much Boost.Proto specific. At the moment they seem to be out of place, especially as they are undocumented, unmaintained and not even part of the regular file structure. I would like to see them either fully documented (with the underlying concept of segmented sequences) or in the detail namespace of Boost.Proto. I added support for associative iterators. An associative forward sequence shall provide an iterator type which implements the extension backend of the intrinsic (meta-)functions fusion::result_of::value_of_data, fusion::deref_data and fusion::result_of::key_of. This has the advantage that all view classes, even fusion::iterator_range, are able to adapt the underlying sequence's associative-ness. fusion::transform_view, as a special case, got an additional template parameter. This parameter specifies whether the view should model either the forward concept only or the associative and the forward concept. This design breaks consistency with Boost.MPL. Unfortunately these changes are crucial and I would rather risk this break with Boost.MPL than missing that important feature. Using the old implementation, there is no way to avoid explicitly converting from a view back to an associative sequence to preserve the associative-ness. This leads to a nasty runtime overhead due to evaluation of every element of the view and copy-/move-constructing it. Besides, other changes include: -If the compiler supports rvalue references, all fusion container have a template constructor (taking either const lvalue or 'templated' rvalue references). -If the compiler supports variadic templates, fusion::cons, fusion::pair and fusion::single_view have a variadic template constructor (taking either const lvalue or 'templated' rvalue references) that allows emplace construction. -The view classes adapt the full category of their underlying sequences. As mentioned above, the associative-ness is preserved, but also, if possible, the random-access or bidirectional trait. -The result_of::-metafunctions accept r- and lvalue references arguments. If an argument is not reference-qualified, it will be considered to be an lvalue reference. All existing extension implementations must be changed to adapt this new behaviour. -The algorithm functions now also take (and correctly forward) non-const reference arguments. -Fusion iterators (with reference compatible sequence types and a very same index) and views (with reference compatible sequence types) have a working operator= that correctly reassigns the underlying sequence references. -Fusion now also adapts MPL iterators. If, and only if, the <boost/fusion/adapted/mpl.hpp>-header is included, mpl sequences and iterators are recognized as fusion sequences and iterators. -There are new headers to adapt std::(tr1::)array or std::(tr1::)tuple. The overall compile-time performance of my code is satisfying. Compiling a compilation unit that includes all possible fusion headers takes on gcc 4.4 slightly more time than the official fusion implementation. If native variadic templates are present, the compilation is a lot faster (usually up to 3 to 6 times), regardless of the value of FUSION_MAX_xxx_SIZE. The compile-time performance of actual fusion code is mixed. The intrinsic container and iterator (meta-)functions compile a little bit slower compared to the official fusion implementation. This is due to explicit removal of the references on the arguments of all result_of::metafunctions and some additional abstraction layer. If the compiler support rvalue references, there has to be a rather ugly and slow type evaluation/transformation to avoid issues with rvalue references on non-array, non-class types (see /support/internal/ref.hpp and 8.5.3p5 of the current c++0x draft for more details). On the other hand, I added several optimizations (such as result preevaluation), and, if variadic templates are present, the actual instantiation of fusion containers is a lot faster. All in all, the compile-time performance is a little bit worse if c++0x features are not present. If c++0x features are present, the code should compile a little bit faster in most cases. For example, the lambda example of the Boost.Proto documentation, which internally heavily relies on Boost.Fusion, takes on my machine 2.6 seconds to compile with the 'old' fusion on gcc 4.4, 3 seconds with my port without -std=c++0x, and 2.1 seconds with c++0x features being present. The overall performance might be even better once Boost.MPL adapts native variadic templates and the compiler supports template aliases. There have been tons of other changes, mostly bugfixes, optimizations (in terms of compile time of course) and removals of redundancy. Whenever I had the choice, I tried to prefer clean, redundancy-free instead of heavily optimized code. The overall performance loss is not noticeable though, and most compile-time optimizations that go beyond the as-little-template-instantiations-as-possible paradigm are pretty much compiler dependent anyway. There is still some work to do. I did not add c++0x-specific test cases and there are several parts of the documentation which need to be updated. By the way, are there any official guidelines for documenting c++03/c++0x-specific differences? For now, I would like to hold off on implementing these changes until Boost.TypeTraits adapts c++0x. Right now I implemented missing or incorrectly behaving trait functions in the fusion::detail-namespace. I would rather like to use the official ones, at least in the documentation and in the test cases. Besides that, I think my implementation is trunk-ready. If there are no objections, I would like to finish the outstanding work as soon as possible, and then merge my code with the trunk. Of course I will provide long-term support for the project. In fact, I would love to become an official fusion maintainer. You can find the code in the boost sandbox (/sandbox/SOC/2009/fusion). If you test the code with a compiler that has decltype support, please use the HEAD of the trunk rather than the official 1.40 distribution package to compile your code. Best regards Christopher

6 17

Review Request: Boost.Itl; The Interval Template Library
by Joachim Faulhaber 03 Oct '09

03 Oct '09

Dear developers, the Interval Template Library is now in a state where I think it does conform the requirements and guidelines for boost libraries fairly well. To decide, whether it's design, implementation and overall usefulness is sufficient to be accepted in the boost libraries collection is now up to you. In the last round of refactoring I concentrated on efficiency and optimization issues. The implementation of the itl's interval containers is still based on std::set and std::map, but algorithms are now exploiting hinted insert and are manipulating intervals and values in place instead of copying in many instances. This way, it has been possible to improve performance significantly. Along the way of implementing optimizations I have documented the complexity guarantees for all important functions of the library's interface. Please note that the original ITL as presented in May 2008 has been split into 3 parts and only the *first* part is submitted for review: itl : Core library, interval containers, SUBMITTED FOR REVIEW Additional parts are: itl_xt : Extensions like histories and generalized crosstables validate: The law based test automaton (LaBatea). A validation tool using laws aka axioms. *itl* is a complete library containing all required ingredients particularly a separate test suite (NOT using LaBatea) and the quickbook documentation. The code is successfully compiled and tested with gcc-3.4.4, 4.1.0, 4.3.2 and msvc-8.0, 9.0. I have uploaded the review version as itl_3_1_0.zip to the vault in section containers. http://www.boostpro.com/vault/index.php?action=downloadfile&filename=itl_3_… Another file itl_plus_3_1_0.zip contains all three parts (itl, itl_xt and validate). http://www.boostpro.com/vault/index.php?action=downloadfile&filename=itl_pl… Reviewers interested in the law based testing part may have to refer to this file to examine those tests. The law base testing examples compile and run with gcc-4.3.2, msvc-8.0 and 9.0. LaBatea does not compile with gcc-4.1.0 or older. The quickbook generated documentation is included in the zip files and is also available online at http://herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/index.html Sources are also available form the sandbox: https://svn.boost.org/svn/boost/sandbox/itl/ To close my request for review, let me take the opportunity to do some advertisement ;-) focusing on some of the itl's highlights. * The Itl emerged out of real world software development extracting generic functionality from numerous use cases of the date time problem domain. (http://www.herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/boost_itl/ex…) But the need for the same data structures occurs in other fields as well. E.g. Zachary Turner uses a compressed_bitmap similar to an itl::interval_set to manage very large file system allocation bitmaps and gives more use cases here (http://lists.boost.org/Archives/boost/2009/06/152817.php) * Aggregation on overlap not only provides a useful feature to compute aggregation results on interval_maps like statistics, it also leads to a generalized addition operation on maps that exhibits interesting semantical properties. E.g. (http://herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/boost_itl/semant…) * The itl's design is based on sets of laws (aka axioms) that are described in the documentation. (http://herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/boost_itl/semant…) These law sets not only are giving a formal specification of the library. Using the law based testing tool (LaBatea) (https://svn.boost.org/svn/boost/sandbox/itl/boost/validate) allows to validate the library code for every specified law. * For the itl, 18 laws have been validated on the 7 container templates with varying instantiation types for template parameters, running a total of 719 different law instances (each of them for large numbers of randomly generated test data). (https://svn.boost.org/svn/boost/sandbox/itl/libs/validate/example/) This gives everyone a method to check semantical properties of the library in a way that is more powerful than traditional unit tests. To get the 'complete picture' of the library's interface you may want to refer to the synoptic function table first (http://www.herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/boost_itl/in…) before looking at more specific topics. Hoping to have quickened your appetite to take a closer look at this library before and during the review process. best regards Joachim Faulhaber

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[task]
by Baxter Jeremy 03 Oct '09

03 Oct '09

I have been looking at the boost task library from the vault and comparing it with the threadpools library http://threadpool.sourceforge.net and have a few comments. Firstly I should say that I'm interested in tasks / thread pools for a situation rather different from the one for which they are designed. Namely the case in which threads (tasks) are being used to monitor some internal or external activities and so may block for significant periods of time waiting for the result of a complex planning algorithm or for some condition being met. I'm therefore worried about blocking all the available threads. I think what I need is to be able to dynamically add new threads to the thread pool, or just not use a pool at all and create and destroy a thread for every subtask. However during my review I came across a helper function which I though might allow re-use of the same thread but I'm concerned could actually lead to deadlock: reschedule_until <file:///D:\Boost\boost.task-0.3.0\doc\html\boost_task\utilities.html> In the function boost::this_task::reschedule_until( Pred const&) allows to synchronize the task with other asynchronous events without blocking the worker-threads (bool Pred::operator()() must not block). The current task will be rescheduled until the passed predicate becomes true. Looking at the code I don't think this is an accurate description and gives the potential to introduce deadlocks in tasks which otherwise would operate normally. >From the code what reschedule_until does is repeatedly call the process_ function to look for new tasks, testing once each task has finished to see if the predicate has been met. This is not quite as described since the task is not 're-scheduled' it is actually blocked until whatever task the scheduler next selects is complete. This introduces problems if multiple tasks on the queue use reschedule_until. If there are three tasks T1 T2 and T3 on the queue doing the following: T1 { ... Reschedule_until(A) B.setTrue() ... } T2 { ... Reschedule_until(B) ... } T3 { ... A.setTrue() } What we would like to happen, and what will happen if they are run in different threads (or a different order on the one thread) is that T1 does some work, waits for T3 then terminates. T2 does some work, waits for T1, then does some more work. T3 independently does its work and finishes by signalling that T1 can continue. Unfortunately if they are scheduled in the order T1 T2 T3 then T1 runs, reschedules and T2 gets to run until it reschedules and T3 gets to run. When T3 finishes T1 is in a position when it can run, however it will not get the chance to because in order for condition A to be checked T2 has to have finished, and it can't do that until B is set true. Therefore although progression should be possible as the condition T1 is waiting for has been met it will never notice and T1 and T2 will never complete. I'm not sure that there is a general solution to this problem without using more threads so that any potentially runnable task will get a chance. A second comment. Comparing the task and thread pool libraries they use different waiting mechanisms. Thread pool uses a wait-notify construct on the queue to block worker threads if the queue is empty. Task uses active polling, trying to get items from the queue and then sleeping for a short period if nothing can be found on the queue. I wondered why the difference is there. Wait - notify would look like it should perform better in the case where there are fewer tasks than threads is polling better in the case where there are many more tasks than threads and so threads will never sit idle polling for long? Jeremy Jeremy Baxter Lead Researcher, UAVs & Autonomy Tel: 01684 894801 email: jwbaxter(a)QinetiQ.com www.QinetiQ.com QinetiQ - Delivering customer focused solutions Please consider the environment before printing this email. The information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). The information in this communication may be confidential and/or legally privileged. Nothing in this e-mail is intended to conclude a contract on behalf of QinetiQ or make QinetiQ subject to any other legally binding commitments, unless the e-mail contains an express statement to the contrary or incorporates a formal Purchase Order. For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful. Emails and other electronic communication with QinetiQ may be monitored and recorded for business purposes including security, audit and archival purposes. Any response to this email indicates consent to this. Telephone calls to QinetiQ may be monitored or recorded for quality control, security and other business purposes. QinetiQ Limited Registered in England & Wales: Company Number:3796233 Registered office: 85 Buckingham Gate, London SW1E 6PD, United Kingdom Trading address: Cody Technology Park, Cody Building, Ively Road, Farnborough, Hampshire, GU14 0LX, United Kingdom http://www.qinetiq.com/home/notices/legal.html

3 5

[utility] Fix for const issue of value_initialized merged to release
by Niels Dekker - address until 2010-10-10 03 Oct '09

03 Oct '09

FYI, I have just merged the fix of ticket #2548, regarding value_initialized, to the release branch. The fix has been on the trunk for quite a few months, and Fernando Cacciola has told me he thinks that it's okay to merge it. The fix disables implicit conversion from const value_initialized<T> to non-const T&. More information: Ticket #2548, Let's fix the logical constness of value_initialized!" https://svn.boost.org/trac/boost/ticket/2548 [boost] [utility] A fix for the const issue of value_initialized http://lists.boost.org/Archives/boost/2009/02/148489.php Changeset 56547: Merged value_init from the trunk, including fix of #2548, regarding "const value_initialized" https://svn.boost.org/trac/boost/changeset/56547 Kind regards, Niels -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center

1 0

[Serialization] Question about "Back versionning"
by Vincent Thomas 02 Oct '09

02 Oct '09

Hi, During some testing of boost::serialization features, I tried to do this : Let's say we have a class X, the current version for this class is 5 (BOOST_CLASS_VERSION(X, 5)). Serialize in class X is split into save/load.What I'd like to do now, is save an object of type X at version 3 to make the object loadable by an older version of my software. that is get ""<X class_id="0" tracking_level="0" version="3">" in my resulting file instead of "<X class_id="0" tracking_level="0" version="5">". I've gone through the documentation of boost::serialization and I found only one thing. A TODO speaking about "Back versionning". It's not clear for me if this part speaks about the archive (like xml_oarchive, xml_iarchive, ...) or the object I can serialize, in other words does it concern this line "<boost_serialization signature="serialization::archive" version="5">" or a line like this one "<test class_id="0" tracking_level="0" version="2">" in a resulting file ? Maybe it concerns both but that I don't know. So apparently If I understand the documentation correctly I can't do what I describe above at the moment. Does anyone know if it's going to be implemented soon, or if I can be of any help ? Vincent

1 0

Hello and a quick question.
by S. Brad Daughdrill 02 Oct '09

02 Oct '09

Hello to all, I first want to say hello to all the members. I recently ran across your project, and I am really interested in working with you all. My question is are there an example that use forms? The example I found all seem to be console applications and while they are helpful, I really want my students to start programming with forms (initially at least). They will be using Visual C++ 2008 Express. Thank you for everything ahead of time. Brad *----- S. Brad Daughdrill The University of Alabama B.S. Management Information Systems M.S. Operations/Project Management M.B.A. Financial Risk M.A. Economics (Candidate) 146 Lenora Drive Tuscaloosa, AL 35401 (o) 205.348.7591, Bidgood Hall - 351E (c) 251.510.3089 (e) S.Brad.Daughdrill(a)Gmail.com*

3 2

threads: how to remotely kill a thread?
by David M. Cotter 02 Oct '09

02 Oct '09

say i'm on the main thread, and i've got a thread::id of some other preemptive thread. i do not have the actual boost::thread object any more. and i want to unceremoniously kill that thread. like right now. how do i kill it? i don't see a way to recover the actual boost::thread from the thread::id. but even if i could, and then call thread.interrupt(), that's more of a polite request which is free to be ignored, rather than a you_must_die_now() thing.

3 2

[BGL] Why source() needs a graph argument?
by Cosimo Calabrese 02 Oct '09

02 Oct '09

Hi to all, the question is in subject. I don't understand it. Either source() and target() functions only return the m_source member and the m_target of edge_base. They don't use the graph argument, that is not even used. I need to know it because I'm implementing an union_graph adaptor, that provides the join's view of 2 graph. When I call the source() function on a union_graph, I provide an edge_descriptor; but whereas the source() function of an adjacency_list needs a graph argument, I need to know which graph belongs the edge, which is an 2 * O|E| operation on 2 graphs. Thanks, Cosimo Calabrese

2 1

"parent_from_member" proposal
by Domagoj Saric 02 Oct '09

02 Oct '09

Sometimes your design contains the typical model<->view / data/logic<->gui separation of classes/objects but at the same time it is static enough that it does not require the also typical dynamic way of connecting the two worlds through pointers and/or signals/events and/or function pointers/callbacks and/or ... In other words: - the two corresponding objects ('model/logic' and 'view/gui') always exist in the same memory space/process - the 'model' always exists when the 'view' exists - one does not mind compile time coupling/compile time hit that will occur if the 'model' and the 'view' classes know which methods they must call on 'the other' object as opposed to knowing which slots to expose/signals to connect to. In such a scenario the typical 'dynamic connection/coupling' approach unnecessarily incurrs overhead both in terms of verbosity and efficiency...it is 'easier' if the 'model' holds the 'view' object by value (or a wrapper class holds them both or whatever other solution as long as their offset in memory is constant)...then the the 'model' knows its 'view' instance implicitly from its this pointer (only a positive offset is required) but the 'view' instance does not know its 'model' instance implicitly (using 'conventional' methods) although it is infact also only a matter of offset calculation from its this pointer (only a negative one in this situation)... Now, if we take into account that the 'model' class knows the name of its 'view' member it can 'create' a pointer-to-member to it thus enabling us to create a sort of an extended and templated version of the standard C offset macro (from stddef.h). Using this 'template offset' functor (called ParentFromMember here, provided by the 'model' class) the 'view' class/instance can now also get to its 'model' instance implicitly from its this pointer (without knowing exactly how or where it exists in relation to the 'model' instance). template <class T> struct DummyStorage { typedef typename std::tr1::aligned_storage < sizeof( T ), std::tr1::alignment_of<T>::value >::type type; }; template < class Parent, class Member, Member Parent::* pMember > class ParentFromMember { public: typedef typename std::tr1::remove_const<Parent>::type Parent; typedef typename std::tr1::remove_const<Member>::type Member; public: Parent & operator()( Member & member ) const { DummyStorage<Parent>::type const parentStorage; Parent const * const pDummyParent( reinterpret_cast<Parent const *>( &parentStorage ) ); ptrdiff_t const offset ( reinterpret_cast<char const *>( &( pDummyParent->*pMember ) ) - reinterpret_cast<char const *>( pDummyParent ) ); return *reinterpret_cast<Parent *>( reinterpret_cast<char *>( &member ) - offset ); } Parent const & operator()( Member const & member ) const { return operator()( const_cast<Member &>( member ) ); } }; ...the DummyStorage part is just 'added-paranoia'...the whole operator() function could (probably ?) be simplified to work just like the offset macro in MSVC's stddef.h (in fact, with MSVC, both approaches produce the same code)...: Parent & operator()( Member & member ) const { ptrdiff_t const offset( reinterpret_cast<ptrdiff_t>( &( reinterpret_cast<Parent const *>( 0 )->*pMember ) ) ); return *reinterpret_cast<Parent *>( reinterpret_cast<char *>( &member ) - offset ); } .... so if you have class View { void someViewFunc(); }; class Model { private: View v; public: typdef ParentFromMember<Model, View, &Model::v> ViewModel; void someModelFunc(); } void View::someViewFunc() { Model & myModel( Model::ViewModel()( *this ) ); myModel.someModelFunc(); } ... If this has any chance of not being against the standard and/or "by-the-book" conventions it could probably be augmented with additional debugging/paranoia checks (for example that classes that would use this would be required to derive from some utility class and/or hold the "Member" object in some templated wrapper that would add GUID-like headers in front of objects in memory to assert that the conversions were called on valid objects and things like that)... The whole approach could also be extended with utility classes like FusionContainerFromMember, ParentFromOptionalMember, MemberFromMember and such... One 'big' problem is that this breaks MSVC (tested with 9.0 SP1 and 10b1) with a compiler error (at the typedef line) when the Parent class (in this case the Model class) is a template class (it compiles fine with the online Comeau compiler). A workaround (for MSVC) that might come to mind is to place the typedef outside the body of the template Parent class (it can also be in a another class) but this no solution as template typedefs do not work and an out-of-body template would require public access to the member/encapsulation breakage...so far the only acceptable solution I could find for MSVC is to use a wrapper metafunction that returns the required ParentFromMember<> specialization... -- "That men do not learn very much from the lessons of history is the most important of all the lessons of history." Aldous Huxley

1 0

[serialization]Double rounding bug?
by Mariusz Kwiczala 02 Oct '09

02 Oct '09

Hello, I found that for some small double value, serialization change last few digits.(it look like some rounding bug) Below is one example (I have more :) usually it is a number 0.00... or 0.00 with 19-20 digits after dot): -0.0070850229047457131 - double value -0.007085022904745714 - double value after save/read from xml file On my computer I have always assert in function DoubleTest(). Boost: version 1.39/boost_serialization-vc90-mt-gd-1_39.dll Compiler: VS2008 Could you verify below code on your computer (call DoubleTest())? Is it bug? Sample code: #pragma warning( push ) #pragma warning( disable : 4512 ) #include <boost/archive/xml_iarchive.hpp> #pragma warning( pop ) #include <boost/archive/xml_oarchive.hpp> #include <boost/serialization/vector.hpp> #include <boost/bind.hpp> #include <fstream> #include <boost/archive/xml_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/serialization/vector.hpp> void LoadDoubleValue(DoubleValue& doubleValue, const char* fileName) { std::ifstream ifs(fileName); assert(ifs.good()); boost::archive:: xml_iarchive ia(ifs); ia >> BOOST_SERIALIZATION_NVP(doubleValue); } void SaveDoubleValue(DoubleValue& doubleValue, const char* fileName) { std::ofstream ofs(fileName); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); oa << BOOST_SERIALIZATION_NVP(doubleValue); } void DoubleTest() { DoubleValue doubleValue1; doubleValue1.m_value = -0.0070850229047457131; SaveDoubleValue(doubleValue1, "DoubleValue.xml"); DoubleValue doubleValue2; LoadDoubleValue(doubleValue2, "DoubleValue.xml"); //but from file is read -0.007085022904745714 assert(doubleValue1.m_value==doubleValue2.m_value); } Best regards, Mariusz

3 2

[BoostCon 2010] Call for Participation
by Hartmut Kaiser 02 Oct '09

02 Oct '09

Please distribute! -------------------------------- 4th Annual Boost Conference 2010 -------------------------------- Aspen CO, USA, May 4-10, 2010, www.boostcon.com Call for participation ---------------------- We invite you to submit session proposals to the 4th Annual Boost Conference: BoostCon 2010 (Aspen CO, USA, May 10-14, 2010). Traditionally the main face-to-face event for all things Boost (www.boost.org) BoostCon 2010 will present leading speakers from the whole C++ community. From using the Boost libraries to writing and maintaining them, from evangelizing to deploying Boost within your organization, from infrastructure and process to vision and mission, and the new C++ Standard, BoostCon brings together the sessions, the colleagues, and the inspiration to support your work with C++ and Boost in particular for the next year. To reflect the breadth of the Boost community, the conference includes sessions aimed at two constituencies: Boost end-users and hard-core Boost library and tool developers. The program fosters interaction and engagement within and across those two groups, with an emphasis on hands-on, participatory sessions. Session topics -------------- Topics of interest include, but are not restricted to, the following: * General tutorial sessions introducing one or more Boost libraries * In-depth sessions on using specific Boost libraries * Case studies on using Boost * Experts panels * Advanced sessions on implementation techniques used within Boost libraries * C++0x and how it will change life for users and library writers * Development workshops to extend or enhance existing Boost libraries * Workshops on design process * Infrastructure workshops such as Build tools, Website, Testing * Concepts and Generic Programming * Hardware and infrastructure presentations focused on how libraries can make better use of the technology * Other topics likely to be of great interest to Boost users and developers Interactive and collaborative sessions are encouraged, as this is the nature of both the on-line Boost community and the style of learning and participation that has proven most successful at such events. Sessions can be tutorial based, with an emphasis on interaction and participant involvement, or workshop based, whether hands-on programming or paper-based, discussion-driven collaborative work. Session formats --------------- Presentations Presentations focus on a practitioner's ideas and experience with anything relevant to Boost and Boost users. Panels Panels feature three or four people presenting their ideas and experiences relating to Boost's relevant, controversial, emerging, or unresolved issues. Panels may be conducted in several ways, such as comparative, analytic, or historic. Tutorials Tutorials are sessions at which instructors teach conference participants specific Boost-relevant skills. Workshops Workshops provide an active arena for advancements in Boost- relevant topics. Workshops provide the opportunity for experienced practitioners to develop new ideas about a topic of common interest and experience. Author's Corner Presentations These were introduced at BoostCon 2008, and were a great success. They are short (30 minute) sessions, focusing on tips on usage and design. In addition, we're looking to uncover the hidden design gems in Boost libraries. Tool Vendors Presentations We actively encourage tool vendors and ISP's to submit proposals for a special Tool Vendors Session Track aimed at products related to Boost and C++ (compilers, libraries, tools, etc.). Other formats may also be of interest. Don't hold back a proposal just because it doesn't fit into a pigeonhole. Submitting a proposal --------------------- Standard Sessions are 90 minutes. You may submit a proposal for fractions or multiples of 90-minutes. Fractional proposals will be grouped into 90 minute sessions covering related topics. Longer sessions, such as tutorials and classes, will be assigned 90 minute, three hour (i.e. half day), or six hour (i.e. full day) time slots. Please include: * The working title. * Type of session: presentation, panel, tutorial, workshop, authors corner, vendor track, other. * A paragraph or two describing the topic covered, suitable for the conference web site. * Proposed length: 10-20 minute short talks, 45 minutes, 90 minutes, half day, full day. * Alternate lengths, if you are willing to make adjustments: 10-20 minute short-talks, 45 minutes, 90 minutes, half-day, full day. * Audience: users, developers, both. * Level: basic, intermediate, advanced. * A biography, suitable for the conference web site. * Your contact information (will not be made public). Submission details ------------------ All submissions have to be done through the EasyChair conference management system: http://www.easychair.org/conferences/?conf=boostcon10. If you have not already registered at EasyChair, you will need to do so in order to submit your proposal. All submissions will go through a peer review process. Authors are invited (but are not required) to submit PDF versions of full papers of up to 10 pages in ACM conference proceedings format (see http://www.acm.org/sigs/publications/proceedings-templates) The full papers are not required unless you want them published in the proceedings. All accepted proposals will be made available in the Association for Computing Machinery (ACM) Digital Library (approval pending). Best papers, after further reviews, will be considered to be book chapters or journal articles in a renowned journal. The session materials go on the BoostCon website and will be available to attendees. For general information on the BoostCon 2010 paper submission or the scope of technical papers solicited, please refer to the conference website at www.boostcon.com. For any other questions about the submission process or paper format, please contact the Program Committee at boostcon10(a)easychair.com. If you have any technical problems with EasyChair, please contact EasyChair for help. Note: Presenters must agree to grant a non-exclusive perpetual license to publish submitted materials, either electronically or in print, in any media related to BoostCon. Important dates --------------- Proposal submissions due: Dec 10th, 2009. Proposals decisions sent (tentative program available): Jan 15th, 2010. Fully scheduled program available: Feb 5th, 2010. Session materials due: Apr 15th, 2010. Hartmut Kaiser, email: hartmut.kaiser(a)gmail.com (Program Committee Chair) David Abrahams, email: dave(a)boostpro.com (Conference Chair) On behalf of the conference organizers

1 0

[rdb] 0.0.10 + documentation
by Jean-Louis Leroy 01 Oct '09

01 Oct '09

I have uploaded a new revision to the vault. The only /visible/ change in the API is the syntax for the insert...select statement. It was `insert_into(table)(cols)(select(...))`, it is now `insert_into(table)(cols).select(...). The syntax engine is beginning to look more and more like a compile-time finite state machine. And there is the beginning of a documentation ! you can view it here : http://www.yorel.be/boost/libs/rdb/doc/html/index.html The tutorial is 2/3 complete for this phase (i.e. sans prepared statements). The structure of the doc is strongly influenced by Fusion's - no wonder, I spent so much time in it ;-) While I like the overall structure, I wonder if the Fusion style is appropriate for a tool that is not so much into meta-programming (well at least on the outside). I documented insert_into in this fashion (see http://www.yorel.be/boost/libs/rdb/doc/html/rdb/sql_subsystem/statements/in…) for a test. If you have opinions, please voice them. J-L

2 2

[mpl] Can we generate this type in a simpler way?
by vicente.botet 01 Oct '09

01 Oct '09

Hi, I want to generate the following type R1::mth1_<T1, R3::mth1_<T3, C::mth1_> > > from mpl::vector<mpl::pair<R1, T1>, mpl::pair<R3, T3>, C and mth1_? I have started with this template <typename SequenceOfPairs, typename E, ??? MTH> struct generator { typedef ??? type; }; but I don't know what MTH'can be, because we have 3 different mth1_. So I have reached to make a specific mth1_generator (for the specific symbol 'mth1_') template <typename SequenceOfPairs, typename E> struct mth1_generator { typedef ??? type; // The details of the type are ommited using 'mth1' }; satisfying mth1_generate<mpl::vector<mpl::pair<R1, T1>, mpl::pair<R3, T3>, C>::type is equal to R1::mth1_<T1, R3::mth1_<T3, C::mth1_> > > ? As aal the mthX_generator follow the same structure, I have defined a macro DEFINE_GENERATOR which will define the specific generator for a symbol MTH #define DEFINE_GENERATOR(MTH) \ template <typename SequenceOfPairs, typename E> struct MTH##_generator { typedef ??? type; // The details of the type are ommited suing now MTH. } So the user will just have to do DEFINE_GENERATOR(mth1); Can I do it in a simpler way using some kind of traits or this is an inherent preprocessor problem? Thanks for clarifications, _____________________ Vicente Juan Botet Escribá

1 0

[mpl]haskell-like list comprehension
by Larry Evans 01 Oct '09

01 Oct '09

A recent post about variadic fusion: http://article.gmane.org/gmane.comp.lib.boost.devel/194407 contained, in the test driver attachment, a pair of templates: test test_impl These two templates were used to, in effect, test a cross product from the domains {0...24,0...24}. This was a use-case for something like haskell's list comprehension: http://www.haskell.org/haskellwiki/List_comprehension There's now a prototype of an mpl list_comprehension class in the boost vault: http://www.boostpro.com/vault/index.php?directory=variadic_templates& the output from the file is: { 9000, 9010, 9020} { 9000, 9010, 9021} { 9000, 9011, 9020} { 9000, 9011, 9021} { 9000, 9012, 9020} { 9000, 9012, 9021} { 9001, 9010, 9020} { 9001, 9010, 9021} { 9001, 9011, 9020} { 9001, 9011, 9021} { 9001, 9012, 9020} { 9001, 9012, 9021}

1 0

[Asio] Why does Boost Asio only allow 64 buffers to be sent/recei ved using scatter/gather?
by Stephens Patrick 01 Oct '09

01 Oct '09

Hi all, Apologies if this question should be directed at an Asio-specific list but I could not see one. I originally posted on the users list so trying the developers list now. I am curious why the Boost Asio library specifies a maximum of 64 buffers can be used for scatter/gather operations? I would like to gain a better understanding as to why this value was used. The documentation (http://www.boost.org/doc/libs/1_40_0/doc/html/boost_asio/overview/implement ation.html), and the code backs it up, seems to specify that the maximum allowed will be 'min(64, IOV_MAX)' for linux implementations. Was this value (64) chosen for some particular reason? What would the consequences be of using IOV_MAX if it was greater than 64? I see that the Windows NT, 2000, XP, 2003 and Vista implementation also has a limit of 64 so is this something limited by the OS or to keep it consistent across all the Asio implementations? I had a look around to see if there was a restriction under Windows but the only documentation I could find (http://msdn.microsoft.com/en-us/library/ms742203%28VS.85%29.aspx) mentions that it is restricted to a value of 16 under Windows 95, 98 and ME, which does tally with what the Asio documentation states in the link above. Thanks for any help, Pat. This email, including any attachment, is a confidential communication intended solely for the use of the individual or entity to whom it is addressed. It contains information which is private and may be proprietary or covered by legal professional privilege. If you have received this email in error, please notify the sender upon receipt, and immediately delete it from your system. Anything contained in this email that is not connected with the businesses of this company is neither endorsed by nor is the liability of this company. Whilst we have taken reasonable precautions to ensure that any attachment to this email has been swept for viruses, we cannot accept liability for any damage sustained as a result of software viruses, and would advise that you carry out your own virus checks before opening any attachment.

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[mpl] set_c with enums
by Domagoj Saric 01 Oct '09

01 Oct '09

void aFunction() { enum AnEnum { First, Second, Third, Fourth }; typedef boost::mpl::set_c<AnEnum, First, Fourth, Third> AnEnumSubSet; bool const exists ( boost::mpl::has_key < AnEnumSubSet, boost::mpl::integral_c<AnEnum, Second> >::value ); } the above code fails to compile in MSVC++ 9.0 SP1 and 10.0b1 with the following error(s): error C2440: 'specialization' : cannot convert from 'int' to 'aFunction::AnEnum' if the AnEnumSubSet definition is changed to use ...set_c<int... everything compiles and works properly (the has_key statement can still use the enum)...everything also works properly (with an enum) when using vector_c and contains instead of set_c and has_key... -- "That men do not learn very much from the lessons of history is the most important of all the lessons of history." Aldous Huxley

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[mpl] at<AssocSeq,Key,Default>
by Domagoj Saric 01 Oct '09

01 Oct '09

the mpl::at<AssocSeq,Key,Default> version for associative containers (still) exists in the documentation but (still) not in the sources (1.40 official ones)... -- "That men do not learn very much from the lessons of history is the most important of all the lessons of history." Aldous Huxley

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How can new members can start contributing to this group?
by Manoj Sharma 01 Oct '09

01 Oct '09

Hi Friends, I have 5 years of development experience on C++ on Solaris. I am new to Boost and want to be active member of this group. Please suggest me how can I proceed to start contributing to this group. Thanks, Manoj Keep up with people you care about with Yahoo! India Mail. Learn how. http://in.overview.mail.yahoo.com/connectmore

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Re: [boost] On the Road to Aspen (BoostCon 2010)
by pete＠pcbartlett.com 01 Oct '09

01 Oct '09

On Tue 29/09/09 12:22 , Joel de Guzman <joel(a)boost-consulting.com> wrote: > Edouard A. wrote: > > Hi Joel, > > > > You can also create a twitter account and link your Facebook page > to this > > twitter account, mirroring all your facebook status updates to > your twitter > > account. > > > > This increases visibility and give the possibility to your fans to > choose > > the medium they like to follow you. > Thanks, Edouard. Done. BoostCon Facebook Linked to > Twitter (@BoostCon) > http://www.twitter.com/BoostCon Many users of Boost are in corporate environments. Many corporate environments block access to Facebook and/or Twitter (mine blocks both) domains. It'd be great therefore if Boost didn't move too much content there if equivalent

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Double free from UTF
by janm-boost-devel＠transactionware.com 01 Oct '09

01 Oct '09

Hi, I am seeing a double free when using boost-test on: - FreeBSD 7.2-STABLE, amd64 (gcc 4.2.1) with boost 1.39 - Mac OSX 10.6.1, x86_64 (XCode 3.2, gcc 4.2) with boost 1.40 I don't see the problem on Windows XP with Visual C++ 2005 Express. A simple test case is below, just run. The _malloc_options is to make the system malloc() fill memory with 0xa5 on allocation and 0x5a on deallocation. #define BOOST_TEST_MAIN #include <boost/test/included/unit_test.hpp> #include <stdlib.h> const char* _malloc_options = "J"; BOOST_AUTO_TEST_CASE(broken) { BOOST_CHECK(true); } Output: Running 1 test case... *** No errors detected zsh: bus error (core dumped) ./a.out Stack Trace: #0 0x0000000800b1bdee in free () from /lib/libc.so.7 #1 0x000000000043e51c in boost::unit_test::framework_impl::clear (this=0x55ad20) at framework.ipp:133 #2 0x000000000043e652 in ~framework_impl (this=0x55ad20) at framework.ipp:122 #3 0x00000000004110c6 in __tcf_1 () at framework.ipp:222 #4 0x0000000800b6dbb6 in __cxa_finalize () from /lib/libc.so.7 #5 0x0000000800b1f7c7 in exit () from /lib/libc.so.7 #6 0x0000000000404595 in _start () Any ideas? Thanks, Jan Mikkelsen

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Interest in flat_iterator for nested containers?
by Christoph Heindl 01 Oct '09

01 Oct '09

Hi, is there any interest in an iterator that provides a flat view of nested containers? For example ---------- using namespace boost::assign; typedef std::list<int> inner_container_type; typedef std::vector<inner_container_type> outer_container_type; outer_container_type elements(6); elements[1] += 1,2,3; elements[2] += 4,5; elements[4] += 6; BOOST_CHECK(std::equal( make_flat_iterator(elements.begin(), elements.end()), make_flat_iterator(elements.end(), elements.end()), list_of(1)(2)(3)(4)(5)(6).begin()) ); ---------- If so, I'll be glad to share my code with the boost community. I attach my current state of development and a single test suite. The current state of development contains a class named flat_iterator, a make_flat_iterator function and a set of meta-functions to derive required types. flat_iterator derives from boost::iterator_adaptor. It derives an inner_iterator type from the passed iterator to be adapted (outer_iterator type). The value_type of outer_iterator is required to model STL container concept. The value_type passed to boost::iterator_adaptor is const-qualified if the reference type of the outer_iterator or inner_iterator type is const-qualified (please see question 1 below). The traversal category of flat_iterator is bidirectional if the the outer_iterator and inner_iterator type are at least bidirectional. It models forward traversal else (question 2). flat_iterators can be stacked over each other to recursively flatten a hierarchy of arbitrary levels. ---------- using namespace boost::assign; typedef std::list<int> level_0; typedef std::vector<level_0> level_1; typedef std::vector<level_1> level_2; level_2 elements(10); elements[2] += list_of(1)(2); elements[4] += list_of(3)(4); typedef flat_iterator<level_2::iterator> flat_iterator_outer; typedef flat_iterator<flat_iterator_outer> flat_iterator_inner; flat_iterator_outer outer_begin(elements.begin(), elements.end()); flat_iterator_outer outer_end(elements.end(), elements.end()); flat_iterator_inner inner_begin(outer_begin, outer_end); flat_iterator_inner inner_end(outer_end, outer_end); BOOST_CHECK(std::equal(inner_begin, inner_end, list_of(1)(2)(3)(4).begin())); ---------- Open questions: * Currently the the value_type passed to boost::iterator_adaptor is const qualified based on required reference type of the outer_iterator, which renders the code for input iterators unusable, right? What's the best way to achieve const correctness? * The traversal category of flat_iterator is supposed to be the 'greatest common divisor' of the inner and outer iterator type. Is there a meta-function in boost that provides that type? Currently bidirectional traversal is chosen if both, inner and outer iterator, are at least of bidirectional traversal. Else forward traversal is chosen (which is of course incorrect when incrementable is passed). * Stacking flat_iterators to flatten out a hierarchy of arbitrary levels is possible but currently requires a lot of typing. I think that applying some recursive meta-functions to generate a correct iterator types for such situations should be possible but is beyond my current knowledge of meta-programming. Kind regards, Christoph

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boost::variant and "Current Approach: Temporary Heap Backup" vs "An Initial Solution: Double Storage"
by Peter Foelsche 01 Oct '09

01 Oct '09

1) boost::variant and "Current Approach: Temporary Heap Backup" vs "An Initial Solution: Double Storage" Please provide both solutions. A potential heap allocation may prevent certain application areas. 2) I also do not understand that exception safety requires that the variant is never empty (e.g. empty() returning always false). What is the use of calling the constructor (of which type btw?) if somebody creates an unintialized variant variable? Or: In the following piece of code is the std::string constructor being called? boost::variant<std::string, int> s; Thanks Peter

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