February 2011 - Boost - lists.preview.boost.org

[parameter] std proposal
by Lorenzo Caminiti 07 Jan '13

07 Jan '13

Hello all, Is there a C++ standard proposal for named parameter addition? I am looking for an "N-paper" for named parameters similar to N2081 for concepts, or N1962 for contracts. Thank you. -- Sent from my mobile device Lorenzo

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[#pragma once]
by Sid Sacek 18 Nov '12

18 Nov '12

I've worked with the MSVC, Sun and GCC compilers. Each one of them supports #pragma once. Is there any reason to wrap this pragma within #ifdefs? Are there any compilers out there today that don't support this #pragma? #if defined( _MSC_VER ) && ( _MSC_VER >= 1020 ) # pragma once #endif Could we change this coding pattern so that it no longer looks like MSVC is being selfish? -Sid Sacek

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[config] explicit call of operator templates / msvc bug workaround
by Stefan Strasser 10 Oct '12

10 Oct '12

Hi, is there already a macro in Boost.Config that allows you to insert the "template" keyword in the following code for those compilers that require it? struct functor{ template<class T> void operator()(); }; template<class F> void g(F f){ f.template operator()<int>(); //(1) works with GCC and comeau f.operator()<int>(); //(2) works with MSVC } this apparently only applies to operator calls. MSVC accepts both (1) and (2) for regular functions. (instantiating the operator template with an object of type T as argument, like mpl::for_each does, is not an option. I can't construct T.) thanks, Stefan

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status of sp_counted_base_solaris.hpp
by Graham Bennett 07 Jun '12

07 Jun '12

Hi all, I'm interested in getting boost::shared_ptr to use atomic ops on Solaris. I notice there is an implementation using the OS-provided atomics in boost/detail/sp_counted_base_solaris.hpp, but it doesn't seem to be included. According to this thread: http://lists.boost.org/Archives/boost/2006/07/107144.php, it seems the reason might be that it wasn't possible to come up with a proper preprocessor condition to include it on the right versions of Solaris. I'm considering modifying my boost installation to include this header on Solaris - does anyone know of any issues with the code, or can they confirm that it has been well tested? Are there any other reasons for its omission? Thanks, Graham -- Graham Bennett

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[mpl] integral_c [type_traits] integral_constant limits
by vicente.botet 04 Jan '12

04 Jan '12

Hi, I was testing Boost.Ratio with gcc-4.6 c++0x and I get some compile errors when instantiating std::cout << boost::mpl::integral_c< boost::intmax_t, boost::integer_traits<boost::intmax_t>::const_max >::value ; ..\..\..\../boost/mpl/aux_/integral_wrapper.hpp: In instantiation of 'mpl_::integral_c<long long int, 0x7fffffffffffffffll>': ratio_io\ratio_io.pass.cpp:24:6: instantiated from here ..\..\..\../boost/mpl/aux_/integral_wrapper.hpp:72:96: warning: integer overflow in expression [-Woverflow] ..\..\..\../boost/mpl/aux_/integral_wrapper.hpp:72:96: error: '-0x8000000000000000ll' is not a valid template argument for type 'long long int' because it is a non-constant expression ..\..\..\../boost/mpl/aux_/integral_wrapper.hpp:72:96: error: '-0x8000000000000000ll' is not a constant expression integral_wrapper.hpp:72 contains typedef AUX_WRAPPER_INST( BOOST_MPL_AUX_STATIC_CAST(AUX_WRAPPER_VALUE_TYPE, (value + 1)) ) next; The same line pass with gcc-4.6, gcc-4.5 and gcc-4.5 c++0x with just a warning. ..\..\..\../boost/mpl/aux_/integral_wrapper.hpp: In instantiation of 'mpl_::integral_c<long long int, 0x7fffffffffffffffll>': ratio_io\ratio_io.pass.cpp:23:6: instantiated from here ..\..\..\../boost/mpl/aux_/integral_wrapper.hpp:72:96: warning: integer overflow in expression [-Woverflow] integral_c is by integral_constant, but integral_constant doesn't needs next a prior types. This means that with the current implementation we can not use integral_constant with the max value of the type. Do you think this is a bug in integral_constant? Best, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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[interprocess] message_queue hangs when another process dies
by Sergei Politov 03 Nov '11

03 Nov '11

Hi, I have found the following problem with message_queue on win32 (MSVC 2008 + Windows Vista). Suppose we have 2 processes, one sends messages to queue, another reads them. When reading process dies (for instance using End process) during message_queue.receive the another process hangs in send. As I found during investigation, it tries to lock interprocess mutex, but it is already locked by dead process. So this message queue instance becomes unusable. I attached the example. Steps to reproduce: 1) Start "mq.exe s" (i.e. with argument s) It outs: sender: $PID 2) Start mq.exe without arguments. It outs: receiver: $PID 0 1 2 3 4 This time sender outs: send done: 3) At this point the message queue is empty and receiver waits for messages. End it with Task Manager. 4) Enter some number in sender console and press Enter. 5) The sender hangs in message_queue.send Best Regards, Sergei

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Build trunk 1.46 libraries problems
by Paul A. Bristow 04 Oct '11

04 Oct '11

I've just updated trunk, and note that version.hpp has been updated to 1.46. When I try to link previous tests, I get messages like LINK : fatal error LNK1104: cannot open file 'libboost_test_exec_monitor-vc100-mt-sgd-1_46.lib' But when I try to rebuild the libraries, they are all still *1.45.* :-( my log file is attached. I also note some config failures that suggest something else may be wrong? ...updating 1 target... compile-c-c++ i:\boost-trunk\boost\bin.v2\libs\math\config\msvc-10.0\debug\threading-multi \has_gcc_visibility.obj has_gcc_visibility.cpp libs\math\config\has_gcc_visibility.cpp(7) : fatal error C1189: #error : "This is a GCC specific test case". call "C:\Program Files\Microsoft Visual Studio 10.0\VC\vcvarsall.bat" x86 >nul cl /Zm800 -nologo @"i:\boost-trunk\boost\bin.v2\libs\math\config\msvc-10.0\debug\threading-mul ti\has_gcc_visibility.obj.rsp" ...failed compile-c-c++ i:\boost-trunk\boost\bin.v2\libs\math\config\msvc-10.0\debug\threading-multi \has_gcc_visibility.obj... ...failed updating 1 target... Performing configuration checks - ../config//has_gcc_visibility builds : no ...found 47 targets... ...updating 1 target... compile-c-c++ i:\boost-trunk\boost\bin.v2\libs\math\config\msvc-10.0\debug\threading-multi \has_long_double_support.obj has_long_double_support.cpp ...updated 1 target... - ../config//has_long_double_support builds : yes ...found 15 targets... ...updating 4 targets... compile-c-c++ i:\boost-trunk\boost\bin.v2\libs\regex\build\msvc-10.0\debug\threading-multi \has_icu_test.obj has_icu_test.cpp libs\regex\build\has_icu_test.cpp(12) : fatal error C1083: Cannot open include file: 'unicode/uversion.h': No such file or directory call "C:\Program Files\Microsoft Visual Studio 10.0\VC\vcvarsall.bat" x86 >nul cl /Zm800 -nologo @"i:\boost-trunk\boost\bin.v2\libs\regex\build\msvc-10.0\debug\threading-mul ti\has_icu_test.obj.rsp" ...failed compile-c-c++ i:\boost-trunk\boost\bin.v2\libs\regex\build\msvc-10.0\debug\threading-multi \has_icu_test.obj... ...skipped <pi:\boost-trunk\boost\bin.v2\libs\regex\build\msvc-10.0\debug\threading-mul ti>has_icu.exe for lack of <pi:\boost-trunk\boost\bin.v2\libs\regex\build\msvc-10.0\debug\threading-mul ti>has_icu_test.obj... ...failed updating 1 target... I've tried changing boost_root and boost-build environment variables to 1.46 but makes no difference. Suggestions. Thanks. Paul --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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[serialization] or [spirit] JSON Archives
by Fernando Pelliccioni 08 Sep '11

08 Sep '11

Hi, After experimenting with Spirit.Qi to make a JSON parser, I had the need for a serializer. First, I thought I could serialize my model of JSON (json:: value, json: object, etc.), but that was not compatible with boost::serialization. I am currently writing a ARCHIVE for Boost Serialization, but I'm finding some problems in order to implement JSON correctly. The question is, does anyone know about some files to Boost Serialization already finished? I've seen the Archive made by Esteve Fernandez, but do not serve my purpose, because I just need JSON. I would like to develop a JSON parser which in turn is a compatible Boost Serialization serializer . Any ideas? Thanks and regards, Fernando Pelliccioni.

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[Opaque] Request for interest in Opaque typedefs library emulation
by vicente.botet 27 Jul '11

27 Jul '11

Hi, I have started to play with a class to define opaque typedefs on funcdamental types. It is based on the C++ proposal " Progress toward Opaque Typedefs for C++0X" by Walter E. Brown http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1891.pdf and http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1706.pdf Please take a look on the preceding links to understand the motivation. Boost.Sericalization provide a BOOST_STRONG_TYPEDEF already, but in my opinon the implementation is not complete,as only the order operators are defined (But maybe I'm wrong). Evidently it can not provide everything we can have with a language approach, but IMO this could yet be useful. The library include two class templates (CRTP) to define opaque types: * public_opaque_type<OT,UT> : implicit conversion from OT to UT * private_opaque_type<OT,UT> : no conversion from OT to UT An opaque type (OT) is a new type, different from the underlying type (UT) and other OT. It defines explicit constructor from the UT, and defines all the operators the UT support but this time applied to the OT. To define a new OT with this mixin classes struct serial_number: public_opaque_type<serial_number, unsigned> { BOOST_OPAQUE_PUPLIC_FORWARD_CONSTRUCTORS(serial_number,unsigned); }; struct game_score: private_opaque_type<game_score, unsigned> { BOOST_OPAQUE_PRIVATE_FORWARD_CONSTRUCTORS(game_score,unsigned); }; In addition, defines macros that make this simpler BOOST_OPAQUE_PUBLIC_TYPEDEF(unsigned, serial_number); BOOST_OPAQUE_PRIVATE_TYPEDEF(unsigned, game_score); Next follows the definition of the public_opaque_type template <typename Final, typename T> class public_opaque_type : boost::totally_ordered< Final , boost::integer_arithmetic< Final , boost::bitwise< Final , boost::unit_steppable< Final , boost::totally_ordered< T, Final // public specific conversions , boost::integer_arithmetic< T, Final // public specific conversions , boost::bitwise< T, Final // public specific conversions > > > > > > > { protected: T val_; typedef public_opaque_type opaque_type; public: typedef T underlying_type; explicit public_opaque_type(const T v) : val_(v) {}; public_opaque_type() {}; public_opaque_type(const opaque_type & rhs) : val_(rhs.val_) {} public_opaque_type & operator=(const opaque_type & rhs) { val_ = rhs.val_; return *this; } public_opaque_type & operator=(const T rhs) { val_ = rhs; return *this; } T const& underlying() const { return val_; } T& underlying() { return val_; } operator const T & () const { return val_; } operator T & () { return val_; } #if 0 bool operator==(const opaque_type & rhs) const { return val_ == rhs.val_; } #endif bool operator<(const Final & rhs) const { return val_ < rhs.val_; } Final& operator+=(const Final & rhs) { val_ += rhs.val_; return static_cast<Final&>(*this); } Final& operator-=(const Final & rhs) { val_ -= rhs.val_; return static_cast<Final&>(*this); } ... }; I have started to make some tests and it works well for the moment. Limitations: * As we can not specialize the behaviour of static_cast/dynamic_cast the library sould provide two specific casts opaque_static_cast and opaque_dynamic_static_cast (Not yet implemented). * As operator.() can not be overloaded, it works transparently only for underlying types that don't defines member functions (C++ fundamental types, as int, char, ...). For the others an explicit use of the underlying() member function is needed :( * Others I have not catched yet :( Do you think it is worth continuing? Please, let me know if you see a error on the design. _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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[filesystem] home_directory_path
by Jeff Flinn 24 Jul '11

24 Jul '11

In looking at implementing a portable home_directory_path function a few questions arise. Based on http://en.wikipedia.org/wiki/Home_directory, POSIX and other UNIX flavors 'appear' to be a straight forward use of the "HOME" environment variable. Does anyone have any experience where the "HOME" variable is not the proper source of the user's home directory? Windows NT and above have the "USERPROFILE" environment variable. Using this would be the easiest to use. But I've seen discussion that this may not always be properly defined, in particular if the user has reset their home directory to a non-system drive. I haven't tracked down it's availability on WinCE. Does anyone have experience with this platform? There is the windows GetUserProfileDirectory api function also available since NT4. This is in the Userenv.lib/dll, obviously adding a link dependancy. How are these sorts of system link dependencies handled? Through bjam? Or is it acceptable/better to use #pragma comment(lib,"Userenv.lib")? In looking at some client code using home_directory_path, I see that they generally are looking for the user's Desktop directory(Mac & Windows). Obviously this only makes sense on GUI platforms. The issue with merely getting this path via home_directory_path() / "Desktop" is IIRC, that at least on windows "Desktop" is localized and may not exist with that name on non-english localized systems. Windows has the SHGetFolderPath api. I need to look into Mac's native support. Any thoughts on the general usefulness of a portable desktop_directory_path? Thanks, Jeff

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