March 2008 - Boost - lists.boost.org

libs/dynamic_bitset/bitset_test unmerged changes?
by David Abrahams 05 Jul '08

05 Jul '08

Should these be in the trunk? Index: bitset_test.hpp =================================================================== --- bitset_test.hpp (revision 40672) +++ bitset_test.hpp (working copy) @@ -1006,7 +1006,8 @@ bool did_throw = false; try { - s << b; + static_cast<void> + (s << b); } #if defined BOOST_OLD_IOSTREAMS catch(...) { @@ -1081,7 +1082,8 @@ const std::ios::iostate except = is.exceptions(); bool has_stream_exceptions = true; try { - is >> b; + static_cast<void> + (is >> b); } catch(const std::ios::failure &) { did_throw = true; -- Dave Abrahams Boost Consulting http://www.boost-consulting.com

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[filesystem] Problems with wpath on Linux
by Alexei Alexandrov 06 Jun '08

06 Jun '08

Hi, I'm trying to use fs::wpath on Linux and I'm encountering some problems with internal conversion of wide strings to external representation. The problem can be demonstrated with the following code: #include <iostream> #include <boost/filesystem/path.hpp> #include <boost/filesystem/convenience.hpp> namespace fs = boost::filesystem; int main() { // Setting the global locale to be environment locale std::locale::global(std::locale("")); // Setting the wpath locale to be global fs::wpath_traits::imbue(std::locale()); fs::wpath mypath(L"/tmp/some/directory"); fs::create_directories(mypath); } To me, this work looks correct and should work. But it terminates with the following message: terminate called after throwing an instance of 'boost::filesystem::basic_filesystem_error< boost::filesystem::basic_path<std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >, boost::filesystem::wpath_traits> >' what(): boost::filesystem::wpath::to_external conversion error Aborted At the same time, the following code works: #include <iostream> #include <boost/filesystem/path.hpp> #include <boost/filesystem/convenience.hpp> #include <libs/filesystem/src/utf8_codecvt_facet.hpp> namespace fs = boost::filesystem; int main() { fs::detail::utf8_codecvt_facet utf8_facet; std::locale loc( std::locale(), &utf8_facet ); fs::wpath_traits::imbue( loc ); fs::wpath mypath(L"/tmp/some/directory"); fs::create_directories(mypath); } which uses a UTF-8 facet from boost itself. The first example should work too - this is my understanding. Who is wrong here - me or boost?

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backwards compatibility
by Steve M. Robbins 03 Jun '08

03 Jun '08

Hello, I realize that Boost doesn't promise ABI compatibility across releases, nor even API compatibility according to the FAQ: How can the Boost libraries be used successfully for important projects? Many of the Boost libraries are actively maintained and improved, so **backward compatibility with prior version isn't always possible**. Deal with this by freezing the version of the Boost libraries used by your project. Only upgrade at points in your project's life cycle where a bit of change will not cause problems. Individual bug fixes can always be obtained from the boost repository. (emphasis mine) OK, but *in practice* is there a large amount of work adapting existing client code to a new release? I'm asking in order to gauge whether it is useful for a linux distribution (Debian) to keep multiple versions of Boost available simultaneously; e.g. 1.34.1 and 1.35. Currently Debian provides only the latest version of Boost. Thanks, -Steve

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[Parameter] template return type
by brook＠biology.nmsu.edu 27 May '08

27 May '08

I am trying to use Boost.Parameter to construct some objects, much like make_tuple(A,B) does except with some of the arguments being optional and replaced by defaults (which may depend on the other arguments). The return type, however, must be a template class with the template arguments dependent on the arguments supplied. Is this possible? How can the return type for a Boost.Parameter frunction be specified as a template type? Thanks for your help. Cheers, Brook

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[boost] [boost][gacap]Is any interesting to "Generating All Combinations and Permutations"？
by Ben Bear 19 May '08

19 May '08

Hi, all `gacap' is template library of "Generating All Combinations and Permutations". It's supper of std::next_permutation() and std::prev_permutation(). There's a old discussion: "[boost] [tr2]Add Combination against std::permutation. HELP!" http://lists.boost.org/Archives/boost/2006/09/110176.php I register a project in sf.net, http://gacap.wiki.sourceforge.net/. Some introductions are here. I put a .zip file in the vault, vault/Algorithms/gacap-0.0.4.zip. http://boost-consulting.com/vault/ It can also be downloaded from http://sourceforge.net/project/showfiles.php?group_id=209093 The package contains: gacap's header files doc/ example/ test/ doc/gacap.txt and doc/classes.txt are important introductions. I test it under three compilers, see doc/compile.txt. It's one year later. Thanks.

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Review Request: Generalization of the Pimpl idiom
by Vladimir.Batov＠wrsa.com.au 17 May '08

17 May '08

I hope I am following the submission procedure correctly. I read the guidelines and I seem to do what is needed. Apologies if I missed something. The code is in the Boost Vault called Pimpl.zip It compiles with GCC 4.1.2 (I use it on Ubuntu 7.04) and MS Visual Studio 2005. Documentation is at DDJ site: http://www.ddj.com/cpp/205918714 Any questions/suggestions/critique - vladimir.batov(a)wrsa.com.au Thanks, Vladimir

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a new release of Join library. Could a review be arranged?
by Yigong Liu 15 May '08

15 May '08

Hi there, I just uploaded a new version of Join library into Vault under "Concurrent Programming". Could a review be arranged? A brief description: "Join is an asynchronous, message based C++ concurrency library based on join calculus. It is applicable both to multi-threaded applications and to the orchestration of asynchronous, event-based applications. It follows Comega's design and implementation and builds with Boost facilities. It provides a high level concurrency API with asynchronous methods, synchronous methods, and chords which are "join-patterns" defining the synchronization, asynchrony, and concurrency." This update includes code cleanup and exploring using Join for dynamic flow based programming. project website: http://channel.sourceforge.net doc: http://channel.sourceforge.net/boost_join/libs/join/doc/boost_join_design.h… download: http://sourceforge.net/project/showfiles.php?group_id=157583 Thanks Yigong

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[Concept Check] - Extending the BCCL with AllocatorConcept
by Michael Fawcett 01 May '08

01 May '08

I recently had the need to code up an AllocatorConcept, and it occurred to me that it might fit well within the BCCL. I noticed that Intrusive also had an allocator concept and wondered if other libraries did too (perhaps under a different name). Would this be of interest as an extension to BCCL? A quick Google search of boost.org shows that dynamic_bitset, multi_index, function, regex, shared_ptr (and I'm sure more) all have Allocator template parameters where it might make sense. For very generic concepts such as Allocator, do they belong in BCCL rather than coded in each library? I've pasted the code below. --Michael Fawcett -- code -- namespace boost { template <typename T> struct AllocatorConcept { typedef typename T::const_pointer const_pointer; typedef typename T::const_reference const_reference; typedef typename T::difference_type difference_type; typedef typename T::pointer pointer; typedef typename T::reference reference; typedef typename T::size_type size_type; typedef typename T::value_type value_type; // TODO: Do we need to do more here, e.g. char_allocator_type::rebind<value_type>::other == T? typedef typename T::template rebind<char>::other char_allocator_type; BOOST_CLASS_REQUIRE(T, boost, DefaultConstructibleConcept); BOOST_CLASS_REQUIRE(T, boost, CopyConstructibleConcept); BOOST_CLASS_REQUIRE(T, boost, EqualityComparableConcept); void constraints() { pointer p = 0; reference ref = *p; const_reference cref = *p; p = value.address(ref); const_pointer cp = value.address(cref); p = value.allocate(1); p = value.allocate(1, 0); value.construct(p, *p); value.deallocate(p, 1); value.destroy(p); size_type s = value.max_size(); } private: T value; }; }

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Boost.Python: Build and Install with Python 2.4 and 2.5?
by Steve M. Robbins 01 May '08

01 May '08

Hi, I'm part of the Debian Boost packaging team, seeking some guidance on how to build and install Boost.Python so that it is usable with all Python versions shipped in Debian. Debian currently ships Python 2.4 and 2.5. When reading the following, keep in mind that Boost.Python is not a Python extension but, rather, a library that eases writing an extension in C++. So it is necessary that the compiled libraries be visible to be linked with user-written C++ code. One idea is to use a user-config.jam file containing using python : 2.4 : /usr ; using python : 2.5 : /usr ; Then run jam twice bjam variant= ... bjam variant= ... python python=2.5 This produces pairs of library files such as bin.v2/.../link-static/libboost_python-gcc42-1_34_1.a bin.v2/.../link-static/python-2.5/libboost_python-gcc42-1_34_1.a (and similar pairs for shared libraries and all other variants). The key item to note is that the two files have the same name. The python version, unlike the GCC version, is not embedded in the library name. So these files cannot both be installed into /usr/lib. The question, then, is how to distinguish them once installed? Should we: 1. Rename the resulting libraries to decorate them with the python version in addition to the gcc version? This could generate libboost_python-py24-gcc42-1_34_1.a libboost_python-py25-gcc42-1_34_1.a 2. Similar to above, but use bjam's --buildid option? This has the drawback that the build ID shows up differently than the GCC version decoration, e.g. libboost_python-gcc42-1_34_1-py24.a libboost_python-gcc42-1_34_1-py25.a 3. Put the libraries in different subdirectories, e.g. /usr/lib/python2.4/libboost_python-gcc42-1_34_1.a /usr/lib/python2.5/libboost_python-gcc42-1_34_1.a 4. Put the default version directly in /usr/lib and the others in subdirectories, e.g. /usr/lib/libboost_python-gcc42-1_34_1.a /usr/lib/python2.5/libboost_python-gcc42-1_34_1.a The drawback to all these approaches is that client code has to be adjusted to build on Debian. Linking against Boost (for non-bjam projects) is already hard enough with the decorated library names that I fear making the situation worse. The attraction of #4 is that at least the variants for the default python version are found in a natural manner. This has some appeal to me, personally, but I worry that it is too easy to build an extension to python 2.5 and link in the wrong Boost.Python library. In contrast, the other options have the advantage that it forces the user to declare which version of Python is being used. I'd appreciate your thoughts. Have I overlooked a better solution? What are the other packagers of Boost.Python doing? In principle, it would be nice to have the Boost libraries named the same across distributions. Thanks, -Steve

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Re: [boost] Release 1_35_0_RC2: Boost Python hello tutorial
by Johannes Brunen 01 May '08

01 May '08

Beman Dawes wrote: > In the meantime, have you tried a more modern version of VC++? > The free download of VC++ 2008 Express Edition, for example. Ok, I just tried the same procedure with the VC++ 2005 (i.e. 8.0) compiler with the same result. It does not generate the .pyd files, neither in release mode nor in debug mode. Thanks, for adding it to the issus list Best, Johannes

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