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[multi-array] compiler errors with visual studio 2012
by nfarnsworth＠web.de 23 Mar '13

23 Mar '13

Hello, have this c++ example which compiles with Visual Studio 2010 but with Visual Studio 2012 I got this compiler errors: 1>------ Build started: Project: MultiArrayDemo, Configuration: Debug Win32 ------ 1> MultiArrayDemo.cpp 1>d:\sandbox\multiarraydemo\multiarraydemo\multiarraydemo.cpp(11):error C2059: syntax error : '<' 1> d:\sandbox\multiarraydemo\multiarraydemo\multiarraydemo.cpp(25) : see reference to class template instantiation 'Data<T>' being compiled 1>d:\sandbox\multiarraydemo\multiarraydemo\multiarraydemo.cpp(11):error C2238: unexpected token(s) preceding ';' ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== The example uses the boost 1.53 version. Here is the example code: #include "stdafx.h" #include <boost/multi_array.hpp> const int rows = 3; const int cols = 5; template<class T> struct Data { typedef boost::multi_array<T,2> data_type; typedef typename data_type::array_view<1>::type view_type; //here is the first error typedef typename data_type::index_range range; Data() :A(boost::extents[rows][cols]) { double tmp[] = {1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0,10.0,11.0,12.0,13.0,14.0,15.0}; A.assign(tmp,tmp+ (rows * cols)); } data_type A; }; int _tmain(int argc, _TCHAR* argv[]) { Data<double>* data = new Data<double>(); Data<double>::view_type myView = data->A[boost::indices[0][Data<double>::range()]]; delete data; return 0; } Does anybody know how to solve this problem? Best regards and thank you in advance Niklas

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[gil] GIL_FORCEINLINE replaced with BOOST_FORCEINLINE?
by Mateusz Loskot 22 Mar '13

22 Mar '13

Hi, In boost/gil/gil_config.hpp, there is GIL_FORCEINLINE defined, but there is no easy way to undef/redefine it. Would it be a good idea to replace GIL_FORCEINLINE with BOOST_FORCEINLINE defined in boost/config/suffix.hpp? Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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Re: [boost] GSOC 2013
by Gottlob Frege 22 Mar '13

22 Mar '13

On Mon, Mar 4, 2013 at 10:42 AM, Mateusz Loskot <mateusz(a)loskot.net> wrote: > On 4 March 2013 15:28, David Bellot <david.bellot(a)gmail.com> wrote: > > The best thing is that you guys write a nice description on the web page > for > > students to know about it. > > So far, we already 3 of them. Great ! > > It may look overwhelming for students too. > As it has been pointed already, few projects that qualify to Boost > are actually feasible within GSoC time frame. > > Something feasible could possibly be done with moving pieces of Adobe's ASL into Boost. http://stlab.adobe.com/index.html Sean Parent has always encouraged Boost to take whatever they wanted from ASL. Tony

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[thread] boost::async and launch::deferred - Runtime Error + PATCH
by Fernando Pelliccioni 22 Mar '13

22 Mar '13

Hi Vicente, hi all, The following code snippet throws an exception at runtime boost::future<int> f1 = boost::async( boost::launch::deferred, []() { return 123; }); int x= f1.get(); //exception thrown I am using Boost Trunk revision 83512 I attached a patch, but I'm not sure that's correct, I had no time to see the full future.hpp code I noticed that according to N3558, the future::is_ready() function should be called "ready". http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2013/n3558.pdf What do you think? Thanks and regards, Fernando.

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Abstract STL Container Adaptors
by Andy Jost 21 Mar '13

21 Mar '13

Hi Boosters, Is there any interest in an abstract container adaptor library (I'll describe what I mean below)? I'm a little surprised if this has never come up in the context of Boost, but I couldn't find anything on the archives. I did find something on stack overflow (http://stackoverflow.com/questions/5329555/abstract-wrapper-for-stl-contain…) but it did not uncover an existing solution. Motivation: Sometimes we want to write functions that take a container as an argument. For instance, say I have a graph object implemented in terms of ``class Node``. I may expose an algorithm like this: void my_algorithm(Node & root, std::set<Node const *> const & marked); In this case, ``root`` is the root of a graph, and ``marked`` is a set of marked nodes. The problem with this approach is that it forces a particular choice of the set implementation onto the caller. He may, for example, prefer to use ``tr1::unordered_set``. We could get around that limitation by using a template parameter, like this: template<typename Set> void my_algorithm(Node & root, Set const & marked); The problem here is that it forces the implementer of ``my_algorithm`` to expose that code and, potentially, recompile it many times (for different Set types). In some cases, particularly when compile times are more critical than execution times, it would be preferable to let the caller choose the set implementation without losing the advantages of separate compilation. A simple solution is to write an adaptor that mimics the interface of ``set``. With that, the function call would appear as shown here: void my_algorithm(Node & root, abstract_set<Node const *> const & marked); Here, abstract_set<Node const *> is implicitly convertible from any type having the interface of std::set<Node const *>. It internally holds a reference to some implementation of a suitable set-like object and mediates interactions with the outside world through virtual methods. It seems the implementation of this would be a straightforward application of type erasure. It seems too easy, in fact, which makes me wonder whether I'm missing something. In any case, is this a good idea? -Andy

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Re: [boost] [config] consexpr workaround
by Krzysztof Czainski 21 Mar '13

21 Mar '13

2010/11/13 vicente.botet <vicente.botet(a)wanadoo.fr> > Hi, > > in order to make easier the introduction of constexpr in a portable way I > would like we add a Boost Config workarround. We can define some macros > depending on whether BOOST_NO_CONSTEXPR is defined or not. > > #if defined(BOOST_NO_CONSTEXPR) > #define BOOST_CONSTEXPR > #define BOOST_CONSTEXPR_OR_CONST const > #else > #define BOOST_CONSTEXPR constexpr > #define BOOST_CONSTEXPR_OR_CONST constexpr > #endif > Hi, Could/should BOOST_CONSTEXPR expand to inline in C++03? If not, could a macro BOOST_CONSTEXPR_OR_INLINE be added? For one thing, constexpr functions are usually (but maybe not always?) good candidates for inlines. But also please consider the following example. Suppose we put the following code in a header file: struct X { BOOST_CONSTEXPR int fun() const; }; BOOST_CONSTEXPR int X::fun() const { return 0; } Now if this file is included in multiple .cpp files, this will fail at link time in C++03 with message "multiple definition of `X::fun()", and it will link fine in C++11. But when BOOST_CONSTEXPR is inline in C++03, the above works. Would making BOOST_CONSTEXPR expand to inline in C++03 do any harm? Cheers, Kris

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Re: [boost] GSOC 2013
by Boris Schaeling 21 Mar '13

21 Mar '13

On Wed, 27 Feb 2013 11:59:31 +0100, David Bellot <david.bellot(a)gmail.com> wrote: > Only 2 projects have been proposed so far for GSOC 2013: wake up Boost ! > > https://svn.boost.org/trac/boost/wiki/SoC2013 Google has started to accept applications from mentoring organizations. I'll have to submit our application in the coming days. If you want Boost to become a mentoring organization for GSoC 2013, please add projects to https://svn.boost.org/trac/boost/wiki/SoC2013 now! Boris

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[container][intrusive] Treap for Boost.Container?
by Phil Endecott 20 Mar '13

20 Mar '13

Dear All, I have been playing with boost::intrusive::treap, and it seems like a useful thing. I think it would be helpful to create a boost::container::treap, i.e. a non-intrusive treap container, implemented using the intrusive version. That could make this useful data structure available to users who wouldn't otherwise need to learn how to use Boost.Intrusive. (While I'm here.... does anyone know about a list-like container that has lower memory overhead when the data type is small, i.e. ints or chars? I was considering something using chunks like a std::list< std::vector<T> >, but insertion would invalidate other iterators in the same chunk, which is unacceptable. Any ideas?) Regards, Phil.

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[units] c++11 features to speed up compilation times
by Oliver Esser 20 Mar '13

20 Mar '13

Hi, I was wondering if there was a policy for boost including C++11 features into the libraries. Obviously there might be many projects out there that do not (yet) have access to a compiler implementing the new standard or choosing not to use such a compiler. Anyways I was looking for a dimensional analysis library for compile time units checking and found Boost.Units to be quite slow at compile time even for the relatively small example code in the quickstart documentation. So I've written a bit of code that follows the approach of Boost.Units but uses C++11 features (constexpr, variadic templates, suffix operator, auto). It is not a complete library that I would use in a production environment, but it looks promising, since compilation times are about a factor 2-3 faster on my machine. It would be great if some of you could take a look. https://github.com/legento/units Maybe one could add an implementation like that to Boost.Units as a C++11 compiler detected feature to speed things up. Maybe I am totally wrong and it is some coincidence that this compiles faster on my platform. I did just minimalistic 'ok it seems to work' testing and was about as thorough with measurements. So see this as an implementation sketch. Regards Oliver

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C++Now 2013 is full [ 53 days before the conference ]
by Marshall Clow 19 Mar '13

19 Mar '13

Whoa. In the immortal words of W.C. Fields, "I expected this, but not so soon" We've set up a wait list in case we get any cancellations. -- Marshall Marshall Clow Idio Software <mailto:mclow.lists@gmail.com> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki

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Re: [boost] [range][iterator] contiguous iterators
by Stefan Strasser 19 Mar '13

19 Mar '13

From [boost-users]: Am 18.03.2013 16:06, schrieb Jeffrey Lee Hellrung, Jr.: > On Sat, Mar 16, 2013 at 7:42 AM, Stefan Strasser <strasser(a)uni-bremen.de > is there any way to generically determine at compiletime whether an > iterator or a boost range refers to contiguous memory? > > is_contiguous<T *>::value == true > is_contiguous<vector<T>::iterator>::value == true > is_contiguous<std::list<T>::iterator>::value == false > AFAIK, not presently, but this has been discussed quite a bit in several > past threads on the Boost developers list. Then I'd like to suggest this again to the maintainers of Boost.Iterator and Boost.Range. I'd also like to suggest another addition to Boost.Range: a RangeOutputIterator, i.e. an OutputIterator that doesn't only accept single values, but assignment of ranges: template<class RangeOutputIterator> ... (...RangeOutputIterator out){ *out=range; where range can be any Boost.Range. You can find an implementation of this concept here, in the form of an back insert iterator that can insert entire ranges into a vector: http://pastebin.com/9M5rPDh9 Using these two things together can make generic algorithms as efficient as is possible, e.g. if the container that is being written to is a vector and the value type is a POD, there's one call to std::memcpy. think e.g. about file or database operations like database.get(1024*1024,out); This is in my "namespace detail" right now and I'd be willing to help make it public and document it. Stefan

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Idea for O(1) hash-table
by Rani Sharoni 19 Mar '13

19 Mar '13

Hi All, I hope that you will find the following idea interesting. I have been using hash-table with, AFAICT, unique implementation and I thought that it might be handy for boost. The hash table is O(1) *non-amortized* lookup via extremely balanced buckets (for example, max 6 entries per bucket). The implementation itself is absurdly simple ;-) The hash-table is basically variation of linear addressing using double-hashing hash-table with special re-insert strategy. Algorithm for linear addressing (easy to adjust for chained hashing): Consider a two dimensional N*K array – N buckets with up to K elements per bucket. Assume that the zero-key is marking an empty entry. Lookup(key): for (hash = key, I = 0 ; I < K ;++i) { hash = HASH(hash); // double-hashing if (A[hash % N][i] == key) return found; } return not-found; Insert(key): for (hash = key, I = 0 ; I < K ;++i) { hash = HASH(hash); // double-hashing if (A[hash % N][i] == 0) { A[hash % N][i] = key; return true; } } return false; The above insert is basically a bounded double-hashing and as-is it has a low utilization (a bit similar to bloom filter). For example, for 100K buckets and K=6 - insert will fail when the table has less than 50% utilization (i.e. fail to insert though most entries are empty). The trick is to perform “re-insert”: Pick some random element, key1, from failed insert phase, replace it with the new key, and (re) Insert(key1). Retrying up to, say, 12 rounds of re-insert improves the utilization, of N=100K/K=6, to ~97%! Table resize is done (if needed) when such repetitive re-insert fails. Altogether this implementation trade-off insert for fast lookup which is very appealing to caches (i.e. insert done in the expensive path - only after a cache miss). Just for comparison, hash-table using naïve liner probing (A[HASH(key)%N][i]) has only ~80% utilization even when using K=128 (i.e. deep buckets)! Such unbalanced behavior is also typical classical hash-tables with link-lists (chained-hashing) since statistically some buckets will outgrow the average. The performance of the classic double-hashing algorithm itself is quite poor when the table is highly utilize since many steps are required to find empty entries. Though this hash-table is general purposed it has some interesting properties: 1) O(1) non-amortized with very low chance for collisions (each key has its own unique “virtual” bucket). 2) Can be implemented on continuous memory without pointers and with excellent utilization 3) Allow wait free implementation of caches (i.e. no lock or even interlocked needed). 4) Allow caches on shared memory – corruption safe/hazard algorithm (assuming at least 64 bit keys). 5) Allow persistent using direct memory to file mapping (i.e. disk representation is same as in-memory one). 6) Average 50% LRU eviction for caches (i.e. on average entry half from the oldest is evicted) BTW – there is little chance for patenting this algorithm since I already published similar idea in the public domain ;-) Thanks, Rani

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[math] Extended float in C++ : Was : Support for libquadmath/ __float128
by Christopher Kormanyos 19 Mar '13

19 Mar '13

There has been some recent discussion on extended floating-point types in C++. >>> So the only way to add Q or q suffixes would be to find a way to query >>> the environment if it is supported. I wonder if GCC with >>> --enable-libquadmath has a kind of query for this. >> I haven't found one - gcc-4.7.2 has all sorts of __SIZEOF_XXX__ >> defines for every last type *except* >> __float128 and __float80 :-( > It won't help now, but is 'more precise types' an issue to > raise with WG21 for the next C++ standard? > Or is Multiprecision the way to go? Is there any definitive interest in adding more precise floating-point types to C++ in the next draft? Here, I am talking about floating-point types with fixed precision such as 24, 54, 113 or more binary digits, and possibly even extending beyond these to potential multiprecision types. See also Boost.Multiprecision. Consider the C language in ISO/IEC 9899:2011 (in other words C11). Extended precision is not specified, but there is a remark in Section 6.11.1: "Future standardization may include additional floating-point types, including those with greater range, precision, or both than long double." Recent specification of fixed-size integer types in C99, C11 and C++11 has drastically improved integer algorithm portability and range. Similar specification of fixed-size floating-point types could potentially improve the C++ language significantly, especially in the scientific and engineering communities. One could envision two ways to go: * Types such as float24_t, float53_t, float113_t, ... * Types such as float32_t, float64_t, float128_t, ...The first set above is intuitively coined from IEE754:2008. It is also consistent with the gist of std::uint32_t, et al --- in so far as the number of binary digits of precision is contained within the name of the data type. Is there any interest in committing to this project? Specification takes a long time and requires a coalition of collaborators. I could potentially contribute to this project as a subordinate author. But I don't feel confident enough to champion such a cause. Best regards, Chris.

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Libaries accepted by not in Boost release yet - suitable for GSoC?
by Paul A. Bristow 19 Mar '13

19 Mar '13

I note there are some libraries that have been accepted but are not yet in a Boost release - and development seems to be stalled. This seems unfortunate - much effect from many people has gone into the whole process but we are not quite there yet - so a lot of work may be wasted? No doubt authors have other more pressing priorities J I spotted "Constrained value" and "endian" for example. Are any accepted but unfinished libraries suitable for Google Summer of Code students - with the task being to knock them into final shape? Is anyone willing to mentor these? Paul --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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[local_function] End scope function name declaration makes code hard to read.
by Mostafa 18 Mar '13

18 Mar '13

(This is a feature request/inquiry.) I'm just now seriously starting to use local_function, and I'm finding that having to "visually parse" until the end of scope to determine the local function name makes the code much harder to read. Is it possible to declare the function name at the beginning of the scope? (I don't mind having to also register the function name at the end of the scope.) Something like: BLF2(add, (int), (int lhs, int rhs)) { return lhs + rhs; } BLF2_REGISTER(add); Having said, I don't see why needing an "ending macro" for the local function scope is a requirement (albeit my understanding of the library internals is limited to implementation annex of the documentation). Can't the start macro just expand to something like: //----------------------------- //Macro Generated Output Start. //----------------------------- //Local class definition. //Local class instance registration. //Out of class method definition starts here: inline void local_add::body(int& sum, const int& factor, const int& num) //----------------------------- //Macro Generated Output End. //----------------------------- //User generated content starts here: { return lhs + rhs; } Thanks, Mostafa

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[docs] How to install boost documentation?
by Mostafa 18 Mar '13

18 Mar '13

I'm having a real hard time trying to figure out how to install boost documentation. Can't find any instructions on boost.org nor any on google. Am I missing something really obvious?

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[gil] Pixel arithmetic operations.
by Harg Tholan 18 Mar '13

18 Mar '13

Hi, Has it ever been considered to overload arithmetic operators for "pixel"? In many situations it may be useful to add, sub or divide the value of two or more pixels. Thanks.

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Re: [boost] [gil] What is the status of the Gil extension numeric?
by Krzysztof Czainski 18 Mar '13

18 Mar '13

2013/2/21 Krzysztof Czainski <1czajnik(a)gmail.com> > Hello, > > During my first steps wit Boost.Gil I bumped onto an example [1], that > uses the numeric extension. For this extension, the the example [1] and a > ling from Boost.Gil docs [4] point to [2], where I couldn't find any Gil > extensions to download. Most Google links pointed to the same page, but I > finally found [3]. > > So my questions are: > a) Is there a plan to add the extension numeric to Boost? > b) Is [3] the newest version? And could the Boost.Gil docs be updated to > point to the right place? > c) I corrected a few bugs in boost/gil/extension/numeric/sampler.hpp -- is > this list the right place to discuss modifications to the numeric extension? > > Regards, > Kris > > [1] http://www.boost.org/doc/libs/1_53_0/libs/gil/example/resize.cpp > [2] http://opensource.adobe.com/gil > [3] http://code.google.com/p/gil-contributions/ > [4] http://www.boost.org/doc/libs/1_53_0/libs/gil/doc/index.html > Hello, Any word about above questions? Regards, Kris

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[test] Any dependency on Boost.Test requires C++11 ?
by John Maddock 18 Mar '13

18 Mar '13

At present any test in Boost.Math that depends on Boost.Test fails for GCC prior to 4.5 because the build script for Boost.Test has: <toolset>gcc:<cxxflags>-std=gnu++0x Is this really required? It looks wrong headed to me: * We already have testers that test both C++03 and C++11 modes - so we don't need this to test C++11 support. * It's presence makes testing gcc in C++03 mode impossible if the library uses Boost.Test - so there may be C++03 breakages that we don't know about because of this. * As mentioned above, this is a hard error for GCC prior to 4.5, so those compilers can't be tested either. Can this be safely removed? Many thanks, John.

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[boost.thread] Documentation code error
by Philip Bennefall 16 Mar '13

16 Mar '13

Hello, In the chapter about synchronization in the boost.thread documentation, where the hello world example with the bank account is being shown, I see a small problem in the class: int GetBalance() { mtx_.lock(); int b = balance_; mtx_.unlock(); return balance_; } I believe it should be: int GetBalance() { mtx_.lock(); int b = balance_; mtx_.unlock(); return b; } Kind regards, Philip Bennefall

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Re: [boost] Help in setupping regression tests on ARM
by Antony Polukhin 16 Mar '13

16 Mar '13

Now it fails with the following error: # Running Boost.Build tests # Using bjam binary in '/home/pi/boost_maintain/run_trunk/tools_bjam/bin.linuxarm' # Getting test case results out of "/home/pi/boost_maintain/run_trunk/results/bjam.log"... terminate called after throwing an instance of 'std::runtime_error' what(): locale::facet::_S_create_c_locale name not valid Aborted Traceback (most recent call last): File "run.py", line 60, in <module> runner(root) File "/home/pi/boost_maintain/run_trunk/tools_regression_src/regression.py", line 205, in __init__ self.main() File "/home/pi/boost_maintain/run_trunk/tools_regression_src/regression.py", line 566, in main getattr(self,action_m)() File "/home/pi/boost_maintain/run_trunk/tools_regression_src/regression.py", line 531, in command_regression self.command_test() File "/home/pi/boost_maintain/run_trunk/tools_regression_src/regression.py", line 333, in command_test self.command_test_process() File "/home/pi/boost_maintain/run_trunk/tools_regression_src/regression.py", line 393, in command_test_process self.regression_log ) File "/home/pi/boost_maintain/run_trunk/tools_regression/xsl_reports/utils/checked_system.py", line 21, in checked_system raise Exception( 'Command sequence "%s" failed with return code %d' % ( commands, rc ) ) Exception: Command sequence "['"/home/pi/boost_maintain/run_trunk/tools_regression/build/bin/gcc-4.6/release/process_jam_log" "/home/pi/boost_maintain/run_trunk/results" <"/home/pi/boost_maintain/run_trunk/results/bjam.log"']" failed with return code 34304 Any ideas how to fix it? -- Best regards, Antony Polukhin

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[detail][lightweight_test.hpp] Proposal to add BOOST_TEST_THROWS to boost/detail/lightweight_test.hpp
by Ion Gaztañaga 16 Mar '13

16 Mar '13

Hi, In my tests I use boost/detail/lightweight_test.hpp as it has nearly all I need to test my libraries with very little overhead. However I needed a simple utility to check if an expression throws an exception and I think it can be added to this header with very little code. See attached patch. Do you find this a good idea? Ok to commit? Best, Ion

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comparing-the-c-standard-and-boost
by Neal Becker 15 Mar '13

15 Mar '13

http://slashdot.org/topic/bi/comparing-the-c-standard-and-boost/

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Re: [boost] [type_traits] Some traits are missing
by Antony Polukhin 15 Mar '13

15 Mar '13

2013/2/28 John Maddock <boost.regex(a)virgin.net>: >> I've created ticket https://svn.boost.org/trac/boost/ticket/8189 >> I can take care of it, so may I commit to trunk to type_triats directly? > > > OK sure, go for it. All the regression tests passed well, documentation updated. Boost.Variant was moved to new type trait and works well (not committed to trunk yet). If all the changes are OK, please merge type traits it to release branch and close #8189. -- Best regards, Antony Polukhin

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Re: [boost] "Re: boost_svn_expor"
by DongInn Kim 15 Mar '13

15 Mar '13

Hi Rene, I am sorry for answering late. I did not know that I disabled receiving the boost mails. > It runs as part of the testing process if a tester has configured things to > not use the svn client directly. Disabling it causes some testers to stop > working. I don't know what the problem is with the cpu usage though as it > should be a rarely executed program as there are a small number of testers > and this would run only a small number of times in a day. > > On Wed, Mar 13, 2013 at 3:37 PM, DongInn Kim <dikim_at_[hidden]> wrote: > > I disabled the script /home/grafik/ > > www.boost.org/boost_svn_export_archive.sh for now. I have no idea what > > invokes the script but it seems that I could not find any troubles with the > > disabled script. > > > > Please let me know if you find anything wrong with the boost web services > > including the svn service. > > > > Regards, > > > > -- > > - DongInn > > > Can you tell me exactly what your test program does? It clearly invoked 4 or 5 apache processes which used almost all the resources. Does it create the 4 ~ 5 apache processes whenever you run the test program? Did you or your cronjob run it at that time? How could it run? Regards, -- - DongInn

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