November 2010 - Boost - lists.boost.org

[interprocess] why not use boost/system/error_code?
by Christian Holmquist 26 Nov '10

26 Nov '10

Hi, Is there any reason to have an own error code wrapper in boost::interprocess/errors.hpp, instead of using boost::system::error_code? Cheers, Christian

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[guidelines] why template errors suck
by Eric Niebler 26 Nov '10

26 Nov '10

This is borderline self-promotion and I fretted posting this. But we a community of advanced C++ library developers and I'd really like feedback about these issues. And they really do involve Boost library development. If we could reach agreement about these techniques, we might want to integrate them into Boost's coding guidelines. http://www.reddit.com/r/programming/comments/diddg/expressive_c_why_templat… Comments? -- Eric Niebler BoostPro Computing http://www.boostpro.com

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Bug-fix volunteers: risks, downsides?
by Jim Bell 26 Nov '10

26 Nov '10

To round out the discussion... What risks or downsides would there be to recruiting a little legion of bug-fix volunteers and turning them loose on the tickets and/or regression matrix?

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[1.44][build] Improving support for VC10 and Adding support for Intel C++ 12
by Jeff Benshetler 26 Nov '10

26 Nov '10

I'm working through updating msvc.jam to better support VC10, primarily so that intel-win.jam works more cleanly for Intel C++ 12. It looks like the last substantial revision to msvc.jam was for VC8, although it still works well for VC9 and VC10. The changes I've made work well; my next post is to Intel about "internal error: 0_1374", which seems to be a catch-all. My overall goal is to better support the new target architectures and optimization features available in VC10 and Intel C++ 12. I'm new here, so I wanted to make sure that 1) I'm not duplicating work; 2) I'm following the appropriate procedure. BTW, I posted to the Boost Build list a couple days ago and there has been no traffic at all. Any guidance is appreciated.

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[filesystem3] CP_ACP vs CP_THREAD_ACP
by Yechezkel Mett 25 Nov '10

25 Nov '10

Whilst moving from filesystem v2 to v3 on Windows I found that the library uses CP_THREAD_ACP to convert between narrow and wide filenames. This is wrong, as I will attempt to explain. Background: Windows uses a number of locales and language settings as described on the following page: http://msdn.microsoft.com/en-us/library/dd319088(v=VS.85).aspx The relevant ones are Language for non-Unicode programs (System Locale), Standards and Formats (User Locale) and Thread Locale. The System Locale defines which code page is used by the system for narrow chars, and is set by the user system-wide. The User Locale is for formatting numbers and sorting and is set by the user system-wide. The Thread Locale is also for formatting numbers and sorting, is per-thread, and defaults to the User Locale but can be changed by the program; however it is recommended in a number of places not to touch it (although the exact reasons seem vague, apparently it can have surprising effects). CP_ACP gives the System Locale code page. CP_THREAD_ACP gives the Thread Locale code page which is rather a strange item considering that the Thread Locale isn't meant for code pages at all! "ANSI" (ie narrow char) API functions (including CreateFileA) use the System Locale code page (CP_ACP). fopen (VC++9.0) just passes the filename through to the Windows API and therefore also uses CP_ACP. fstream (VC++9.0) uses mbstowcs_s, which uses the global C locale (not the global C++ locale). Narrow char windows use CP_ACP. boost.filesystem should therefore either use CP_ACP (to be consistent with the Windows API, fopen and the GUI) or the global C++ locale (to be consistent with fstream). (Using the global C locale seems a strange idea, but since setting the global C++ locale automatically sets the global C locale as well, that seems a good compromise.) Using CP_ACP gives something that "just works", it's almost certainly what is needed. Using the global C++ locale is perhaps theoretically correct; it can be set (by the user) to match CP_ACP as follows: std::locale::global(std::locale(str(boost::format(".%||") % GetACP()).c_str(), LC_CTYPE)); which is likely the correct thing for most programs anyway, and also allows the user to choose something different should that be necessary. (Unfortunately std::locale("") doesn't do the right thing - it takes the user locale for everything, including code page, and as explained above the user locale has nothing to do with code page.) In many (perhaps most) cases the user locale and system locale will be the same, but not always - for example I have the user locale set to English UK (for dates) but the system locale set to Hebrew (I need to be able to use Hebrew in non-Unicode programs). Yechezkel Mett

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[config] compiler/gcc.hpp version 4.5 to update
by vicente.botet 25 Nov '10

25 Nov '10

Hi, in gcc.hpp the last know version is 4.4 // last known and checked version is 4.4 (Pre-release): #if (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 4)) # if defined(BOOST_ASSERT_CONFIG) # error "Unknown compiler version - please run the configure tests and report the results" Is there any new features that should be updated for gcc-4.5? Even if gcc-4.6 has not been released yet it will be useful to update the file for this version also. In particular I'm interested in the consexpr feature. How can I help? Best, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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[context] build error with -std=c++0x
by Charlls Quarra 25 Nov '10

25 Nov '10

Hi, i'm trying to get boost.context (from boost vault) to build with g++ 4.4.1 and 4.5.1 with -std=c++0x on both compilers i'm getting this error: In function `main': test.cpp:(.text+0x94): undefined reference to `boost::contexts::context::operator=(boost::contexts::context&&)' collect2: ld returned 1 exit status the test case is the following code: ------- test.cpp -------------- #include <boost/context.hpp> #include <iostream> using namespace std; void CallWrapper(void* p) { cout << " inside CallWrapper " << endl; }; int main() { boost::context ctx; boost::context current = boost::context::current(); ctx = boost::context::create(CallWrapper, current , 0 , boost::context::default_stacksize); cout << " after creating the context, before executing it " << endl; current.jump_to(ctx); cout << " after executing the context " << endl; }; ----------------------------------- i built the code with this command line: g++ -std=c++0x `pkg-config --cflags boost-1.43` test.cpp -o xtest `pkg-config --libs boost-context` -lboost_context -lboost_system when i remove -std=c++0x from the command line, the code compiles and runs fine Charles J. Quarra

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[move] problem with msvc-10 (BOOST_MOVABLE_BUT_NOT_COPYABLE)
by Oliver Kowalke 25 Nov '10

25 Nov '10

-------- Original-Nachricht -------- Betreff: [move] problem with msvc-10 (BOOST_MOVABLE_BUT_NOT_COPYABLE) Datum: Wed, 24 Nov 2010 20:56:46 +0100 Von: Oliver Kowalke <oliver.kowalke(a)gmx.de> An: boost(a)lists.boost.org Hi, msvc-10 has some problems with boost.move. linker error: LNK2019: unresolved symbol "private __cdecl X::X(class X const&)" Example doc_file_descriptor.cpp (uses BOOST_MOVABLE_BUT_NOT_COPYABLE) does not compile too. g++-4.4.5 accepts the code. ? thx, Oliver #include <boost/move/move.hpp> #include <boost/shared_ptr.hpp> class X { private: BOOST_MOVABLE_BUT_NOT_COPYABLE( X); struct impl_t {}; boost::shared_ptr< impl_t > impl_; X( boost::shared_ptr< impl_t > const& impl); public: X(); static X create(); X( BOOST_RV_REF( X) other); X & operator=( BOOST_RV_REF( X) other); void swap( X & other); }; X::X() : impl_() {} X::X( boost::shared_ptr< impl_t > const& impl) : impl_( impl) {} X X::create() { boost::shared_ptr< impl_t > impl( new impl_t() ); return X( impl); } X::X( BOOST_RV_REF( X) other) : impl_() { impl_.swap( other.impl_); } X & X::operator=( BOOST_RV_REF( X) other) { if ( this != & other) { X tmp( other); swap( tmp); } return * this; } void X::swap( X & other) { impl_.swap( other.impl_); } int main(int argc, char * argv[]) { X x( X::create() ); return 0; }

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[1.45.0] release note are insufficient
by Akira Takahashi 25 Nov '10

25 Nov '10

I have translated the release notes of 1.45.0 into Japanese now(but, don't .qbk). https://sites.google.com/site/boostjp/document/version/1_45_0 In the work, I found the missing library in release note: - Polygon : rev.66403 - Property Tree : #4340 - Serialization : rev.65965, rev.66030, rev.66107, rev.66123 - Thread : #4727, #4531, #2330 -- Akira Takahashi Blog : http://d.hatena.ne.jp/faith_and_brave/

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[config] Variadic template macros in gcc header
by Edward Diener 24 Nov '10

24 Nov '10

Why is there two mutually exclusive macros indicating variadic template support for gcc ? There is the established BOOST_NO_VARIADIC_TEMPLATES which says that any compiler does not have variadic template support. Then I find that for gcc there is also BOOST_HAS_VARIADIC_TMPL which evidently says that the compiler does have variadic template support, and is in no other compiler header file than the gcc one. Since the two config macros are mutually exclusive in the gcc header file, why is there any need for BOOST_HAS_VARIADIC_TMPL ?

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