- Boost - lists.boost.org

Interest in a 'Boost.property' library?
by Metodi Todorov 07 Jul '13

07 Jul '13

Is there any interest of "C# property" like library? struct vec2 { float get_x() const{...} float set_x() const{...} ... property_rw<float, vec2, &vec2::get_x, &vec2::set_x> x; vec2() : y(this) {} }; vec2 v; v.x = 15.0f; cout << v.x << endl; Example: http://sourceforge.net/projects/cproperty/?source=dlp Regards, Metodi Todorov

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Benchmarking for performance?
by Arpan Sen 07 Jul '13

07 Jul '13

Hi Boost Dev, What sort of benchmarking does the community do for performance when moving from one revision to another? Kind of regression numbers for benchmark tests I would say for memory and time required. Does not have to be at an application level - even at a data structure level is a good start. Thanks a lot. Arpan

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Historic of regression tests?
by Joaquin M Lopez Munoz 07 Jul '13

07 Jul '13

The regression tests at http://www.boost.org/development/tests/release/developer/summary.html are constantly updated (of course), but I seem to remember that the version manager used to backup a snapshot of this at each release. Am I right (I found nothing searching through boost.org)? Is there some sort of historic info on regression tests? Thank you, Joaquín M López Muñoz Telefónica Digital

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[log] Setup Windows event log backends
by Renato Forti 06 Jul '13

06 Jul '13

Hi, I am trying setup a basic: <http://www.boost.org/doc/libs/1_54_0/libs/log/doc/html/log/detailed/sink_ba ckends.html#log.detailed.sink_backends.event_log> Windows event log, and I copy and past code from log documentation. My app link with: 1> main.cpp 1> Linking to lib file: boost_filesystem-vc110-mt-gd-1_54.lib 1> Linking to lib file: boost_system-vc110-mt-gd-1_54.lib 1> Linking to lib file: boost_log-vc110-mt-gd-1_54.lib 1> Linking to lib file: boost_thread-vc110-mt-gd-1_54.lib 1> Linking to lib file: boost_log_setup-vc110-mt-gd-1_54.lib 1> Linking to lib file: boost_date_time-vc110-mt-gd-1_54.lib 1> Linking to lib file: boost_chrono-vc110-mt-gd-1_54.lib But I have some link problems: 1>qt.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall boost::log::v2_mt_nt5::sinks::basic_simple_event_log_backend<char>::basic_si mple_event_log_backend<char>(void)" (__imp_??0?$basic_simple_event_log_backend@D@sinks@v2_mt_nt5@log@boost@@QAE@ XZ) referenced in function "class boost::shared_ptr<class boost::log::v2_mt_nt5::sinks::basic_simple_event_log_backend<char> > __cdecl boost::make_shared<class boost::log::v2_mt_nt5::sinks::basic_simple_event_log_backend<char> >(void)" (??$make_shared@V?$basic_simple_event_log_backend@D@sinks@v2_mt_nt5@log@boos t@@@boost@@YA?AV?$shared_ptr@V?$basic_simple_event_log_backend@D@sinks@v2_mt _nt5@log@boost@@@0@XZ) 1>qt.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall boost::log::v2_mt_nt5::sinks::basic_simple_event_log_backend<char>::~basic_s imple_event_log_backend<char>(void)" (__imp_??1?$basic_simple_event_log_backend@D@sinks@v2_mt_nt5@log@boost@@QAE@ XZ) referenced in function "public: void * __thiscall boost::log::v2_mt_nt5::sinks::basic_simple_event_log_backend<char>::`scalar deleting destructor'(unsigned int)" (??_G?$basic_simple_event_log_backend@D@sinks@v2_mt_nt5@log@boost@@QAEPAXI@Z ) 1>qt.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall boost::log::v2_mt_nt5::sinks::basic_simple_event_log_backend<char>::set_even t_type_mapper(class boost::log::v2_mt_nt5::aux::light_function<enum boost::log::v2_mt_nt5::sinks::event_log::event_type __cdecl(class boost::log::v2_mt_nt5::record_view const &)> const &)" (__imp_?set_event_type_mapper@?$basic_simple_event_log_backend@D@sinks@v2_mt _nt5@log@boost@@QAEXABV?$light_function@$$A6A?AW4event_type@event_log@sinks@ v2_mt_nt5@log@boost@@ABVrecord_view@456@@Z@aux@345@@Z) referenced in function "void __cdecl init_logging(void)" (?init_logging@@YAXXZ) 1>qt.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall boost::log::v2_mt_nt5::sinks::basic_simple_event_log_backend<char>::consume( class boost::log::v2_mt_nt5::record_view const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (__imp_?consume@?$basic_simple_event_log_backend@D@sinks@v2_mt_nt5@log@boost @@QAEXABVrecord_view@345@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocat or@D@2@@std@@@Z) referenced in function "protected: void __thiscall boost::log::v2_mt_nt5::sinks::basic_formatting_sink_frontend<char>::feed_rec ord<class boost::log::v2_mt_nt5::aux::fake_mutex,class boost::log::v2_mt_nt5::sinks::basic_simple_event_log_backend<char> >(class boost::log::v2_mt_nt5::record_view const &,class boost::log::v2_mt_nt5::aux::fake_mutex &,class boost::log::v2_mt_nt5::sinks::basic_simple_event_log_backend<char> &)" (??$feed_record@Vfake_mutex@aux@v2_mt_nt5@log@boost@@V?$basic_simple_event_l og_backend@D@sinks@345@@?$basic_formatting_sink_frontend@D@sinks@v2_mt_nt5@l og@boost@@IAEXABVrecord_view@234@AAVfake_mutex@aux@234@AAV?$basic_simple_eve nt_log_backend@D@1234@@Z) What is wrong? Thanks

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[log] Build fail : log (1.44.0) on vc 11 using cxxflags=-Zc:wchar_t-
by Renato Forti 05 Jul '13

05 Jul '13

Hi All, I need use cxxflags=-Zc:wchar_t-, because I will use boost with my QT project! I build boost like this (debug in this case): bjam toolset=msvc-11.0 variant=debug threading=multi link=shared cxxflags=-Zc:wchar_t- But log lib fail with this: call "C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\vcvarsall.bat" x86 >nul cl /Zm800 -nologo @"..\..\..\bin.v2\libs\log\build\msvc-11.0\debug\threading-mul ti\formatter_parser.obj.rsp" ...failed compile-c-c++ ..\..\..\bin.v2\libs\log\build\msvc-11.0\debug\threading -multi\formatter_parser.obj... ...skipped <p..\..\..\bin.v2\libs\log\build\msvc-11.0\debug\threading-multi>boos t_log_setup-vc110-mt-gd-1_54.dll for lack of <p..\..\..\bin.v2\libs\log\build\ms vc-11.0\debug\threading-multi>boost_log-vc110-mt-gd-1_54.lib... ...skipped <p..\..\..\bin.v2\libs\log\build\msvc-11.0\debug\threading-multi>boos t_log_setup-vc110-mt-gd-1_54.lib for lack of <p..\..\..\bin.v2\libs\log\build\ms vc-11.0\debug\threading-multi>boost_log-vc110-mt-gd-1_54.lib... ...skipped <p..\..\..\bin.v2\libs\log\build\msvc-11.0\debug\threading-multi>boos t_log_setup-vc110-mt-gd-1_54.pdb for lack of <p..\..\..\bin.v2\libs\log\build\ms vc-11.0\debug\threading-multi>boost_log-vc110-mt-gd-1_54.lib... ...failed updating 4 targets... ...skipped 6 targets... Anyone can helpeme? Thanks

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gmp-5.1.2 / boost-1.54 / multiprecision lib
by Fred Schneider 05 Jul '13

05 Jul '13

Hello, I'm a bit of a newbie and I ran into some issues using gmp with boost. After building gmp-5.1.2, I tried to build a simple file: boostMathExample.cpp, based on the documentation (using the multiprecision library + referencing gmp): ////////////////////////////////////////// #include <boost/multiprecision/gmp.hpp> using namespace boost::multiprecision; int main(int argc, const char *argv[]) { mpz_int v = 1; // Do some arithmetic: for (unsigned int i = 1; i <= 1000; ++i) v *= i; std::cout << v << std::endl; } /////////////////////////////////////////////// I received the following missing symbol errors when trying to build: g++ -I ~/Dev/C++/gmp-5.1.2 -I ~/Dev/C++/boost boostMathExample.cpp -O2 -o boostMathExample Undefined symbols: "_main", referenced from: start in crt1.10.6.o "___gmpz_init", referenced from: __static_initialization_and_destruction_0(int, int)in cccOFSnR.o __static_initialization_and_destruction_0(int, int)in cccOFSnR.o "___gmpz_clear", referenced from: ___tcf_1 in cccOFSnR.o __static_initialization_and_destruction_0(int, int)in cccOFSnR.o "___gmpz_set_si", referenced from: __static_initialization_and_destruction_0(int, int)in cccOFSnR.o ld: symbol(s) not found collect2: ld returned 1 exit status ======================================== I'm running the following version of g++: i686-apple-darwin10-g++-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5666) (dot 3) I configured gmp, version 5.1.2 with the following flags: ./configure --enable-cxx CXX=g++ CXXFLAGS=-O2 CC=g++ CFLAGS="-g -O2" and then ran "make" and "make check". Any insight would be appreciated. Thanks, Fred

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[algorithm][minmax_element] implementation question
by Michael Marcin 04 Jul '13

04 Jul '13

I was looking at minmax_elemement to try and understand the algorithm. I noticed that the boost implementation looks significantly more complicated than the clang libc++ implementation. Mainly due to the potential_min_result variable that exists in the boost version. Is there a reason for this discrepancy? Is there a bug in the clang implementation? http://llvm.org/svn/llvm-project/libcxx/trunk/include/algorithm http://www.boost.org/doc/libs/1_54_0/boost/algorithm/minmax_element.hpp

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Re: [boost] [utility][thread] result_of - erroneous result type from a C++11 lambda
by Klaim - Joël Lamotte 04 Jul '13

04 Jul '13

On Tue, Apr 2, 2013 at 7:16 PM, Vicente J. Botet Escriba < vicente.botet(a)wanadoo.fr> wrote: > I've started to use C++11 lambda functions with Boost.Thread. > > The following works with clang-3.2 > > boost::future<int> f1 = boost::async( []() -> int {return 123;} ); > > > But it fails with gcc-4.6.2, 4.7.2 and 4.8.0 > > ../example/lambda_future.cpp:**25:91: erreur: conversion from > ‘boost::future<void>’ to non-scalar type ‘boost::future<int>’ requested > boost::future<int> f1 = boost::async( []() -> int {return 123;} ); > > The current implementation of boost::async uses boost::result_of to get > the result type of the callable parameter. > > Is this a know bug on boost::result_of or gcc compiler? > I'm seeing exactly the same behaviour in *VS2012 Update 2*. I'm using Boost 1.54.0 beta *r84748* To be more precise: 1) I first was just using boost::future and tried to use the new .then(), here is a full repro: #include <boost/thread/future.hpp> auto ft = boost::async( []{ return 42; } ).then( []( boost::future<int> r ){ return 666; } ); This fails because boost::async() returned a future<void> instead of a future<int>. I suspect the then() call to have the same problem. I can provide the full error log but I think it's not that useful. 2) Just to be sure I tried this full test: #include <boost/thread/future.hpp> int main() { auto ft = boost::async( []{ return 42; } ); // SUCCEED: static_assert( std::is_same< decltype(ft), boost::future<void> >::value, "WTF???" ); // FAILS: static_assert( std::is_same< decltype(ft), boost::future<int> >::value, "Not the expected type!" ); } Both asserts confirm that I don't get what I want. 3) I remembered that there were some issues from usage of boost::result_of in Boost.Log, so to clarify the situation I setup the following full test: #include <boost/utility/result_of.hpp> #include <type_traits> int top() { return 42; } struct K { int operator()(){ return 42; } typedef int value_type; }; auto F = []{ return 42; }; int main() { // A: ALL SUCCEED static_assert( std::is_same< decltype(K()()), int >::value, "Not the expected type!" ); static_assert( std::is_same< decltype(top()), int >::value, "Not the expected type!" ); static_assert( std::is_same< decltype(F()), int >::value, "Not the expected type!" ); // B: ALL SUCCEED static_assert( std::is_same< std::result_of<K()>::type, int >::value, "Not the expected type!" ); static_assert( std::is_same< std::result_of<decltype(top)>::type, int >::value, "Not the expected type!" ); static_assert( std::is_same< std::result_of<decltype(F)()>::type, int >::value, "Not the expected type!" ); // C: ALL SUCCEED std::result_of<K()>::type a = K()(); std::result_of<decltype(top)>::type b = top(); std::result_of<decltype(F)()>::type c = F(); // D: ALL FAILS static_assert( std::is_same< boost::result_of<K()>::type, int >::value, "Not the expected type!" ); static_assert( std::is_same< boost::result_of<decltype(top)>::type, int >::value, "Not the expected type!" ); static_assert( std::is_same< boost::result_of<decltype(F)()>::type, int >::value, "Not the expected type!" ); // E: ALL FAILS boost::result_of<K()>::type d = K()(); // error C2182: 'd' : illegal use of type 'void' boost::result_of<decltype(top)>::type e = top(); // error C2182: 'e' : illegal use of type 'void' boost::result_of<decltype(F)()>::type f = F(); // error C2182: 'f' : illegal use of type 'void' } This shows clearly that: 1. boost::result_of don't behave like std::result_of on this platform (and from previous discussions, on other platforms too). 2. both std::result_of and decltype() provide the result I expect from reading documentations about these. So far I'm assuming that the problem really is from boost::result_of, but I might be wrong because the differences with std::result_of are not clear to me. ---- Unfortunately this makes future.then() unusable if we expect return types. I don't know if it impacts other libraries (I suspect Boost.Log). Should I report a bug or is it known, already fixed or a misuse? Joel Lamotte

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[result_of] Documentation update for ticket 7753
by Nathan Crookston 03 Jul '13

03 Jul '13

Hi Daniel & all, I'm updating the patch for ticket 7753 ( https://svn.boost.org/trac/boost/ticket/7753) I've made the requested changes to the patch, but I had a question on how to best explain which macro to define if, for example, you want result_of to work with C++11 lambdas. In the past, users with a pre-N3276 decltype have been advised to just #define BOOST_RESULT_OF_USE_DECLTYPE, with the explanation that "it's probably just going to work." While that advice is true, there are cases where this doesn't work; hence the addition of BOOST_RESULT_OF_USE_TR1_WITH_DECLTYPE_FALLBACK. To explain why you'd define the FALLBACK macro over the USE_DECLTYPE macro, I'm thinking of including a paragraph like the following. "The question naturally arises on why have both BOOST_RESULT_OF_USE_DECLTYPE and BOOST_RESULT_OF_USE_TR1_WITH_DECLTYPE_FALLBACK. In many situations, BOOST_RESULT_OF_USE_DECLTYPE will work well, even with pre-N3276 decltype. However, there are cases where a post-N3276 decltype is required to correctly deduce the return type of a functor. If a translation unit includes a functor whose return type is only deducible with TR1 or a post-N3276 decltype, using result_of with, e.g. a C++11 lambda function, will fail without BOOST_RESULT_OF_USE_TR1_WITH_DECLTYPE_FALLBACK. If the macro BOOST_NO_CXX11_DECLTYPE_N3276 is defined and BOOST_NO_CXX11_DECLTYPE is not defined when including result_of.hpp, defining BOOST_RESULT_OF_USE_TR1_WITH_DECLTYPE_FALLBACK is the safest option that will allow you to deduce C++11 lambda return types." My question is, am I over explaining it? Of course, I'd rather have BOOST_RESULT_OF_USE_TR1_WITH_DECLTYPE_FALLBACK defined automatically for compilers like VC10, g++4.5, etc., and include text like the following: "If you rely on the result of calling a nullary functor to be void, regardless of the actual return type, or if your code is not written to handle cases other than BOOST_RESULT_OF_USE_TR1 and BOOST_RESULT_OF_USE_DECLTYPE, you may wish to explicitly define one of those symbols prior to including result_of." Either way, comments welcome. Thanks, Nate

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Want to contribute, need advice.
by Manmohit Rekhi 03 Jul '13

03 Jul '13

Hello, Am Manmohit Rekhi, a 2nd year computer engineering student at Nirma university, India. I have some programming experience in c and c++. Am interested in contributing to Boost, and would like to ask a few questions, to help me get started. I would be really grateful is, i could get the following questions answered. 1) Do i need to be familiar with the code of the standard c++ libraries, and if so, where do i start? 2) What other per-requisites are there? 3) Where do i start reading the boost libraries(i mean which file to read first)? Thanking You, Manmohit Rekhi

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