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RFC : About forking a C++11 standard library and adapt it to C++98 compilers
by Vicente J. Botet Escriba 03 Jun '16

03 Jun '16

Hi, Some of us have to work yet with C++98 compiler at work (due to well know reasons) and this for a long time. This is a reality. I was wondering about forking a public domain C++11/14/17 standard library and adapt it to C++98 compilers. This library could be seen as another TR1, an extension of the C++03 standard library. Does this make any sens? Would this project be of interest for the Boost/C++ community? I have not a clear idea of the cost of doing this work, how it should be done, what would be the limitations, ... but I'm sure that this would be quite useful on the projects that are forced to use C++98 and an excellent bridge to those that will move from C++98 to C++11 compilers. There are some Boost libraries that could be used to reduce the limitations, as Boost.Config/Predef, Boost.Move, ...and others that could be used as inspiration on how to implement them using C++98. Anyway, if you find that this will be useful to you at your work we will need your participation. Would you be interested in working on it? as a Boost community project? outside Boost, as an independent project? Comments and suggestion welcome. Best, Vicente P.S. The same can be done for C++14 standard libraries and the future standard C++17 libraries P.S.S. The same can be done for C++14 libraries and the future C++17 libraries but this time adapting to C++11 compilers (this will be much easier but the concerned community will be quite different ).

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[build] error: target { link%link.do-link-recursively-chrono/stopwatches-headers. } has no type
by Nat Goodspeed 02 Jun '16

02 Jun '16

Steven, what do these errors mean, and how can I fix them? https://travis-ci.org/BorisSchaeling/boost-process/builds/134823441 This travis script is trying to embed the candidate Boost.Process library in a boost_1_61_0 tarball tree and build libs/process/test. But I must admit I've been stumped by similar errors several times before. /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/build/generators.jam:1102: in ensure-type from module generators error: target { link%link.do-link-recursively-chrono/stopwatches-headers. { libs/chrono/stopwatches/include/boost. } } has no type /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/build/generators.jam:1359: in generators.construct from module generators /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/build/targets.jam:1553: in construct from module object(typed-target)@1725 /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/build/targets.jam:1353: in class(a)basic-target.generate from module object(typed-target)@1725 /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/build/targets.jam:774: in generate-really from module object(main-target)@1862 /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/build/targets.jam:746: in class(a)main-target.generate from module object(main-target)@1862 /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/build/targets.jam:272: in class(a)project-target.generate from module object(project-target)@1721 /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/build-system.jam:714: in load from module build-system /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/kernel/modules.jam:295: in import from module modules /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/tools/build/src/kernel/bootstrap.jam:139: in boost-build from module /home/travis/build/BorisSchaeling/boost-process/boost_1_61_0/boost-build.jam:17: in module scope from module

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Linker error when using time_from_string
by nick.snels＠telenet.be 02 Jun '16

02 Jun '16

The following code gives an error for the time_from_string function (from_time_t works just fine): using namespace boost::posix_time; ptime epoch = from_time_t(0); ptime other = time_from_string("2011-08-09 17:27:00.000000"); The error is: main.obj:-1: error: LNK2019: unresolved external symbol "public: static class boost::shared_ptr<class std::map<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,unsigned short,struct std::less<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >,class std::allocator<struct std::pair<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const ,unsigned short> > > > __cdecl boost::gregorian::greg_month::get_month_map_ptr(void)" (?get_month_map_ptr@greg_month@gregorian@boost@@SA?AV?$shared_ptr@V?$map@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@GU?$less@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@2@V?$allocator@U?$pair@$$CBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@G@std@@@2@@std@@@3@XZ) referenced in function "unsigned short __cdecl boost::date_time::month_str_to_ushort<class boost::gregorian::greg_month>(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??$month_str_to_ushort@Vgreg_month@gregorian@boost@@@date_time@boost@@YAGAEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) I’m using Qt Creator, along with Visual Studio 2015. I have the installed the windows binary of boost 1.61.1 .

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installing on a local 2 core system
by Salvador Aguiñaga 30 May '16

30 May '16

> Installing on small system I want to use for temporary development, I get the following error. > > >parallel-bgl-0.7.0/boost/property_map/property_map.hpp:16:37: fatal error: boost/pending/cstddef.hpp: No such file or directory > compilation terminated > > I've configured the system: > >"sudo apt-get install build-essential" > > And successfully installed the openmpi: "openmpi-1.10.2.tar.bz2" > > But when I get to: > /parallel-bgl-0.7.0/build/cmake .. > > I can't find a good solution online to this cstddef.hpp error. > > Any suggestions? > > > My system: uname -a > > Linux atomix 4.2.0-16-generic #19-Ubuntu SMP Thu Oct 8 14:46:51 UTC 2015 i686 i686 i686 GNU/Linux

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[proto] non-proto objects as terminals
by Igor R 30 May '16

30 May '16

I would like to use instances of a non-proto class as proto terminals for all purposes. To enable this functionality, I use is_terminal metafunction that I pass to BOOST_PROTO_DEFINE_OPERATORS(). This actually defines the operators, so the following expression makes an expression tree, as expected: non_proto_obj * proto_obj; However, I cannot do this: non_proto_obj = proto_obj; Or this: non_proto_obj[proto_obj]; While the opposite does compile: proto_obj = non_proto_obj; proto_obj[non_proto_obj]; How to solve this issue? Thanks! P.S.: here is an sscce: /////////////////// #include <iostream> #include <boost/proto/proto.hpp> #include <boost/mpl/int.hpp> namespace mpl = boost::mpl; namespace proto = boost::proto; using proto::_; template<typename Expr> struct my_expression; struct my_domain : proto::domain<proto::generator<my_expression> > {}; template<int I> struct placeholder {}; template<typename Expr> struct my_expression : proto::extends<Expr, my_expression<Expr>, my_domain> { explicit my_expression(Expr const &expr = Expr()) : my_expression::proto_extends(expr) {} BOOST_PROTO_EXTENDS_USING_ASSIGN(my_expression<Expr>) }; const my_expression<proto::terminal<placeholder<1>>::type> _1; namespace app { struct non_proto_type {}; template <typename T> struct is_terminal : mpl::false_ {}; template<> struct is_terminal<non_proto_type> : mpl::true_ {}; BOOST_PROTO_DEFINE_OPERATORS(is_terminal, my_domain) non_proto_type non_proto; } int main() { _1 = app::non_proto; // ok, builds temporary proto expression //app::non_proto = _1; // does not compile! no operator= _1[app::non_proto]; // ok //app::non_proto[_1]; // does not compile! no operator[] (+app::non_proto)[_1]; // ok! applying unary + to make a proto expression first, then operator[] is available }

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Boost.Fiber mini-review May 23 - June 1
by Nat Goodspeed 30 May '16

30 May '16

Hi all, The Boost.Fiber candidate library by Oliver Kowalke begins a mini-review today, Monday May 23, which will close Wednesday June 1. It was last reviewed in September 2015; the verdict at that time was "not yet." Oliver has been working steadily to address review comments and to improve the library in other ways, and has brought the library back for mini-review. The updated documentation is here: http://olk.github.io/libs/fiber/doc/html/index.html The code is on the master branch of this repository: https://github.com/olk/boost-fiber/tree/master I believe it is Oliver's intention to respond to review feedback on the develop branch, leaving the master branch stable during the review. I will monitor reviews and discussion on both the boost-users@ list and the boost@ developers' list. Please include at least "fiber" and "review" in the subject line of your mail, e.g. by replying to this message. (Please reply to only ONE list, however.) I will also check the Boost Library Incubator for Fiber reviews: http://rrsd.com/blincubator.com/bi_library/fiber/?gform_post_id=859 though I check that less frequently than email. Please do remember to state in your review whether you think the library should be accepted as a Boost library. Thank you for your interest and your feedback! ----------------------------------------------------- Here follows a synopsis of issues raised during the September 2015 review: Cross-thread fiber migration: Evidently the community strongly desires the ability to transfer a suspended fiber from one thread to another. Now supported, with documentation. Cross-thread migration support implies a requirement to document the thread safety requirements of the customization API. Addressed. Standard required timing specifications: meet (30.2.4 Timing specifications [thread.req.timing]). Addressed. Adapt one or more existing test suites for thread facilities to validate the correctness of the Fiber library's synchronization constructs. The requester clarified in private mail that I misstated his suggestion: he wanted Oliver to review one or more such test suites to discover the kinds of issues that can arise with thread synchronization constructs. He has professed himself satisfied with the current state of the Fiber library's synchronization constructs. std::chrono support: ensure that wait_until() can accept any supported time_point specialization. Addressed. C++11 compatibility. Addressed. Document that this_fiber::yield() (et al.) are valid from main(), or in general from a thread function, as well as from explicitly-launched fibers. Addressed. Make shared_state lock requirements explicit: for example, make mark_ready_and_notify_() accept a std::unique_lock<>& (or &&) to force its caller to provide one. Addressed. Avoid holding mutex during condition_variable::notify_*() calls. Addressed. packaged_task must not decay-copy its task arguments. Addressed. Align fibers::async() signature, result description and invoke_helper implementation with std::async(). Avoid returning std::move(...). Addressed. Wait list implementation: try an intrusive linked list of fiber_context objects. Addressed. Avoid sleeping thread when no fibers are ready -- block on external event. Better handling of waiting tasks (decentralized wait queues?). Addressed. Optimization to resume awakened fiber on the thread that awakens it. Hooks provided. Template redundancy: eliminate duplication between specializations for T, T& and void. The future, shared_future, shared_state, promise and task_object templates were specifically cited. Addressed. Leverage predicate-based condition::wait() overload internally. Addressed. Nested schedulers: make schedulers be schedulable entities themselves. Not implemented. Improve robustness of `promise' handling in Asynchronous Callbacks documentation. Avoid overconfident remarks about it. Addressed. Fix Note overstating the requirements on condition_variable::wait(). Addressed.

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[test] how to test std::pair with BOOST_TEST
by Tan, Tom (Shanghai) 29 May '16

29 May '16

The following snippet does not compile with VS2015 and boost 1.61. What should the correct way to do it? Thanks. // compile with cl.exe /EHSc #define BOOST_TEST_MODULE pair #include <boost/test/included/unit_test.hpp> std::pair<uint32_t, uint32_t> v() { return std::make_pair(0, 0); } BOOST_AUTO_TEST_CASE(range) { BOOST_TEST(std::make_pair(0, 0) == v()); } Here's the error message: C:\3rd\boost_1_61_0\boost/test/tools/assertion.hpp(163): error C2678: binary '==': no operator found which takes a left-hand operand of type 'std::pair<int,int>' (or there is no acceptable conversion) C:\3rd\boost_1_61_0\boost/function/function_base.hpp(740): note: could be 'bool boost::operator ==(boost::detail::function::useless_clear_type *,const boost::function_base &)' C:\3rd\boost_1_61_0\boost/function/function_base.hpp(728): note: or 'bool boost::operator ==(const boost::function_base &,boost::detail::function::useless_clear_type *)' C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE\exception(329): note: or 'bool std::operator ==(const std::exception_ptr &,const std::exception_ptr &) throw()' [found using argument-dependent lookup] C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE\exception(334): note: or 'bool std::operator ==(std::nullptr_t,const std::exception_ptr &) throw()' [found using argument-dependent lookup] C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE\exception(339): note: or 'bool std::operator ==(const std::exception_ptr &,std::nullptr_t) throw()' [found using argument-dependent lookup] C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE\system_error(365): note: or 'bool std::operator ==(const std::error_code &,const std::error_code &) noexcept' [found using argument-dependent lookup] C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE\system_error(373): note: or 'bool std::operator ==(const std::error_code &,const std::error_condition &) noexcept' [found using argument-dependent lookup] C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE\system_error(381): note: or 'bool std::operator ==(const std::error_condition &,const std::error_code &) noexcept' [found using argument-dependent lookup] C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE\system_error(389): note: or 'bool std::operator ==(const std::error_condition &,const std::error_condition &) noexcept' [found using argument-dependent lookup] C:\3rd\boost_1_61_0\boost/function/function_base.hpp(799): note: or 'bool boost::operator ==<T>(Functor,const boost::function_base &)' with [ T=std::pair<int,int>, Functor=std::pair<int,int> ] C:\3rd\boost_1_61_0\boost/function/function_base.hpp(790): note: or 'bool boost::operator ==<T>(const boost::function_base &,Functor)' with [ T=std::pair<uint32_t,uint32_t>, Functor=std::pair<uint32_t,uint32_t> ] C:\3rd\boost_1_61_0\boost/test/tools/assertion.hpp(163): note: while trying to match the argument list '(std::pair<int,int>, std::pair<uint32_t,uint32_t>)' C:\3rd\boost_1_61_0\boost/test/tools/assertion.hpp(326): note: see reference to class template instantiation 'boost::test_tools::assertion::op::EQ<ValType,T,void>' being compiled with [ ValType=std::pair<int,int>, T=std::pair<uint32_t,uint32_t> ] s.cpp(14): note: see reference to class template instantiation 'boost::test_tools::assertion::binary_expr<ExprType,std::pair<uint32_t,uint32_t>,boost::test_tools::assertion::op::EQ<ValType,T,void>>' being compiled with [ ExprType=boost::test_tools::assertion::value_expr<std::pair<int,int>>, ValType=std::pair<int,int>, T=std::pair<uint32_t,uint32_t> ] C:\3rd\boost_1_61_0\boost/test/tools/assertion.hpp(377): warning C4624: 'boost::test_tools::assertion::binary_expr<ExprType,std::pair<uint32_t,uint32_t>,boost::test_tools::assertion::op::EQ<ValType,T,void>>': destructor was implicitly defined as deleted with [ ExprType=boost::test_tools::assertion::value_expr<std::pair<int,int>>, ValType=std::pair<int,int>, T=std::pair<uint32_t,uint32_t> ]

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Call for Papers for Meeting C++ 2016 ends on Friday night!
by Jens Weller 25 May '16

25 May '16

Hello Boost Community! a short reminder, that the deadline is coming up for submitting your talk to this years Meeting C++ conference! Meeting C++ 2016 Page: http://meetingcpp.com/index.php/mcpp2016.html Talk submission page: https://meetingcpp.com/mcpp/submittalk/ thanks, Jens Weller

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File-mapped shared memory access through Boost interprocess is slow on some HPC file-systems due to mmap
by Scott Ritchie 24 May '16

24 May '16

Hi all, I'm wondering if there is some way to use the Boost interprocess library without the use of mmap for file I/O? I have developed an R-language package that uses another third party package (bigmemory) to access objects in shared memory when parallelising R across multiple cores. This third party package uses the Boost interprocess library to make these file-backed shared memory objects available to R. This worked perfectly, until I tested my package on a multi-node cluster. After some digging I found that the code calling these shared memory objects was extremely slow, and had hugely variable runtimes. Accessing these shared memory objects became exponentially slower as I parallelised over more and more cores. After talking to the authors of the bigmemory library and the administrators of the cluster, we have determined the route cause to be the use of mmap() on that particular filesystem (GPFS). On this filesystem, mmap() performs concurrency checking on every read and write since the filesystem is shared across multiple physical nodes. Marking the shared memory segments as read_only did not solve the issue. The advice of the cluster administrators is to not use mmap() for file I/O. I'm hoping there is a simple fix, such as a compilation flag I can provide to boost to use some alternative file I/O function/library? If not I will need to rewrite my code so that it is multi-threaded instead of multi-process without the use of Boost. Kind regards, --- Scott Ritchie, Ph.D. Student | Integrative Systems Biology | Pathology | http://www.inouyelab.org The University of Melbourne ---

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[Parallel Boost Graph Library] General Questions and Redistribution Questions
by Jun Kudo 24 May '16

24 May '16

Hi everyone, I've been playing around with the Parallel Boost Graph Library in hopes of using it for a distributed mesh with redistribution capabilities. Unfortunately, I've been having a lot of issues and I was hoping to get some clarification from the community on some points. I am trying to construct a distributed graph that represents a mesh. The idealized plan is to use this library to create a mesh class that allows for the easy introduction of new vertices and edges as well as repartitioning/data migration capabilities. For this effort, I created a simple struct called Cell that is attached as an interior vertex property and identified the cell id value as the key for indexing. I've attached a short program to really quickly demonstrate what I've been trying to prototype. At this point, I have some questions regarding some things about the library that I can't seem to figure out. 1. How do you control the initial distribution of the names? That is, how do you control which processes own what vertex names when you dynamically add named vertices? 2. How do you create a VertexProcessorMap to use with the redistribution function? The test adjlist_redist_test.cpp looks like it creates a property_map of the vertex_rank but I'm not sure how to do something similar when I have named graph. 3. Is there any way and any point to accomplish what I'm trying to do without using named graphs? I started down this route because the referenced test did not use named graphs. I quickly ran into a situation where I did not know how to grab a vertex descriptor for an off-process vertex without using the vertex(vertices_size_type n, const adjacency_list& g) function or without knowing a priori where that vertex lived. Similar to the named graph situation, I want to be able to dynamically add numbered vertices (which according to the documentation invalidates the use of vertex()) on different processes and then define edges between them based on these numbers. Does the fact that I'm trying to use a global numbering system as a name convention make this question silly? Sorry about the wall of text and I hope my questions are not too nonsensical! Thanks in advance for all the help. Sincerely, Jun

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