- Boost - lists.preview.boost.org

[variant] Applying a portion of fixes
by Antony Polukhin 12 Jul '13

12 Jul '13

Hi, I'd like to fix this issue: https://svn.boost.org/trac/boost/ticket/8772 Apply patch for this issue: https://svn.boost.org/trac/boost/ticket/7911 And take care of this: https://svn.boost.org/trac/boost/ticket/8717 Patches and ideas for fixes are described in tickets. If there'll be no objections till next weekend I'll commit the fixes. -- Best regards, Antony Polukhin

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Boost 1.54.0 released!
by Marshall Clow 11 Jul '13

11 Jul '13

Release 1.54.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains five new libraries and numerous enhancements and bug fixes for existing libraries. New Libraries: Log: Logging library, from Andrey Semashev. TTI: Type Traits Introspection library, from Edward Diener. Type Erasure: Runtime polymorphism based on concepts. For details, including download links, see http://www.boost.org/users/news/version_1.54.0 You can also download directly from SourceForge: http://sourceforge.net/projects/boost/files/boost/1.54.0/ To install this release on your system, see http://www.boost.org/doc/libs/release/more/getting_started/index.html Thanks, --The Boost release team Beman Dawes Daniel James Eric Niebler Marshall Clow Rene Rivera Vladimir Prus

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Regression tests report page stuck
by Joaquin M Lopez Munoz 11 Jul '13

11 Jul '13

Hi, the trunk testing bot http://www.boost.org/development/tests/trunk/developer/summary.html seems to be stuck since ~1.5 days ago. Thank you, Joaquín M López Muñoz Telefónica Digital

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[gil] Portability of new code issue.
by Harg Tholan 11 Jul '13

11 Jul '13

Hi all, Christian has been working on some new features for GIL, such code works fine in Windows 7 with VS11, but it will fail to compile with GCC in Debian Wheezy. I've been trying to figure out why is this failing and possible workarounds with no success. For those with time wanting to help: 1. You will need boost-trunk. 2. I have attached the "bleeding edge" code (a pair of .hpp) as well as a test case. 3. Compile: g++ subsampled_test.cpp -o ss -lboost_unittesting_framework My Compiler Version: g++ (Debian 4.7.2-5) 4.7.2 Errors: yuv_image.hpp:234:38: error: expected primary-expression before ‘,’ token subsampled_test.cpp:28:41: required from here ../yuv_image.hpp:234:5: error: ISO C++ forbids comparison between pointer and integer Note: I have attached the code here because I had to fix some template code, adding/removing 'tyepename', as well as prevention of template parameter shadowing. As you already know, Microsoft's compiler is very 'flexible', allowing non-standard code to compile. Regards, Juan.

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[filesystem] Please take care of #8706
by Antony Polukhin 10 Jul '13

10 Jul '13

Hi, There is a ticket https://svn.boost.org/trac/boost/ticket/8706 and patch in it that fixes compilation of Boost.Filesystem under Android NDK. Tested patch under latest NDK and it works well. Fix is required to start regression tests for droid platform. -- Best regards, Antony Polukhin

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[function] Bind to std::function if supported?
by Andrew Ho 09 Jul '13

09 Jul '13

The boost::move library binds to std::move/T&&/etc. when the compiler supports such features, and only uses work-around mechanisms when the compiler lacks such support. Should we add similar support for boost::function? something like: #ifdef BOOST_FUNCTION_USE_STANDARD_LIBRARY_FUNCTION // alternative: #ifndef BOOST_NO_CXX11_HDR_FUNCTIONAL #include <functional> namespace boost { using ::std::function; } #else // whatever boost::function currently does #endif // ... something similar for boost::bind and std::bind I haven't looked at boost::atomic yet, but we could also consider similar bindings to std::atomic if the library doesn't already do so.

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[shared_array] Why not in C++11 ?
by Sid Sacek 09 Jul '13

09 Jul '13

Does anyone know why 'boost::shared_array<>' was not made part of C++11, since pretty much all the other smart pointers were? -Sid

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[context] SSE/AVX registers preservation
by Andrey Semashev 09 Jul '13

09 Jul '13

Hi, I've been looking at Boost.Context and wondering whether it preserves SSE/AVX state on context switches. From the code it doesn't look like the case - only jump_x86_64_ms_pe_masm.asm contains the code that saves some (not all) xmm registers and ymm registers are never saved. Is this intentional or the library simply doesn't support SSE/AVX? And why not use xsave/xrstor to consistently support all future extensions?

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Re: [boost] Interest in a 'Boost.property' library?
by Joe Mucchiello 08 Jul '13

08 Jul '13

Personally, I always consider properties with getters/setters an anti-pattern for OOP languages like C++. Class interfaces should include only those methods that describe logically valid actions one might take on instances of the class. The idea of properties might sometimes be appropriate. But often times, programs will see a hammer and treat everything they see after it as nails. It becomes easy to add a few more getters and setters for "the rest" of the implementation details and you lose proper encapsulation. Usually when I find a class with lots of get/set methods I find a class with very little thought used when that class was designed.

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[log] Setup Windows event log backends
by Renato Forti 08 Jul '13

08 Jul '13

Work well, on win 7/vc 11! Win 8/vc 11, don't work! mc is not detected! On Thu, Jul 4, 2013 at 11:38 PM, Renato Forti <re.tf(a)acm.org> wrote: > Hi, > I did, but don't work! I have mc, and I remove bin.v2. But boost build > don't find my mc :( > > - message-compiler : no > - compiler-supports-ssse3 : yes > - compiler-supports-avx2 : yes > - gcc visibility : no > - long double support : yes > > C:\boost_1_54_0>mc > Microsoft (R) Message Compiler Version 1.12.9200 Copyright (c) > Microsoft Corporation. All rights reserved. > > No cached! I am on Windows 8, and vc11! Thanks again! Hm, that's strange. Perhaps, a Win 8 thing? What does bin.v2/config.log say? _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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[unordered] a strange limitation for move emulation in Boost.Unordered
by Joaquin M Lopez Munoz 08 Jul '13

08 Jul '13

Here: http://www.boost.org/doc/html/unordered/compliance.html#unordered.complianc… it reads: "Non-copyable objects can be stored in the containers, but without support for rvalue references the container will not be movable." Why not? Container movement does not ever touch its elements, so I don't see the connection. Joaquín M López Muñoz Telefónica Digital

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boost-1.54 needs a bugfix!
by Oliver Kowalke 08 Jul '13

08 Jul '13

unfortunately boost-1.54 needs a bugfix - because my request to merge boost.coroutine into release a required bugfix was not applied :( I'm wondering because the regression-tests are passed?! what to do? should I modify the fix in boost-release and archives of boost-1.54 are rebuild?

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[fusion] Adapter for std::array
by Mateusz Loskot 07 Jul '13

07 Jul '13

Hi, I have prototyped Fusion adapter for std::array, as an attempt to clear the related feature request: https://svn.boost.org/trac/boost/ticket/8241 Here is the functional and testable code of the adaptor : https://github.com/mloskot/boost_fusion_std_array I will appreciate any critique and comments. Unfortunately, I have hit the apparently well-known problem. It is the Fusion begin/end ADL issues with C++0x range-based for and such, as discussed and reported here: http://lists.boost.org/Archives/boost/2010/12/174199.php https://svn.boost.org/trac/boost/ticket/4028 There has been no feedback to the ticket #8241, so I'm not sure what is the Fusion authors' view on std::array adoption. So, a couple of questions: Do the Fusion authors consider any cure for the ADL issues? If not, despite the inconvenience of use of qualified names, would it be still possible to accept std::array into Fusion? Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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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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[Serialization] Constructor for polymorphic archives
by Bjorn Reese 03 Jul '13

03 Jul '13

I have a set of my own Boost.Serialization archives (e.g. [1]) that I wish to write polymorphic variants of. I have tried to follow the blueprint from polymorphic_text_iarchive, which inherits from polymorphic_iarchive_route. The problem is that the constructor of my archives takes iterators (begin and end) as arguments, but the polymorphic_iarchive_route constructor expects a std::stream argument. Is there any workaround for this? [1] http://sourceforge.net/p/protoc/code/ci/master/tree/include/protoc/transenc…

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[Operators] Update, const-correctness and operator chaining
by Andrew Ho 02 Jul '13

02 Jul '13

Hi, I was doing some testing with Daniel Frey/Marc Glisse's proposed 4- overload set for binary operators. For reference, here's the overload set applied to commutative addition: friend T operator +( const T& lhs, const T& rhs) { T nrv(lhs); nrv += rhs; return nrv; } friend T operator +(T&& lhs, const T& rhs) { return std::move(lhs += rhs); } friend T operator +(const T& lhs, T&& rhs) { T nrv(lhs); nrv += boost::move(rhs); return nrv; } friend T operator +(T&& lhs, T&& rhs) { return boost::move(lhs += boost::move(rhs)); } This allows this to be done: val1 + val2 = val3; changing the return type to const T would allow the compiler to catch this, but now doing val1 + val2 + val3 must always use copy semantics instead of move semantics. I can't think of a way which would fix this issue without breaking the use of move semantics. How should we proceed with this? It's obviously bad usage, but the compiler should be able to catch this since it's easy to mistype + as =. Interestingly enough, doing testing with std::string shows the same "problem": std::string str1("hello"), str2(" "), str3("world"); str1 + str2 = str3; I tested this issue with std::string and found it in vs2012, gcc 4.3.2, and mingw/gcc 4.8.0. I don't have access to a compiler which pre-dates C++0x/C++11 so I don't know if this issue has always been present. Compiling with gcc 4.8.0 with - std=c++03 still has the issue.

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