June 2016 - Boost-users - lists.preview.boost.org

Query on Boost DLL Library
by Leo Carreon 09 Jun '16

09 Jun '16

Hi, In Boost DLL Library factory method example it uses boost::shared_ptr and boost::filesystem, can these be replaced by std::shared_ptr and std::experimental::filesystem? Kind regards, Leo

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Re: [Boost-users] [boost] RFC : About forking a C++11 standard library and adapt it to C++98 compilers
by Vicente J. Botet Escriba 07 Jun '16

07 Jun '16

Le 06/06/2016 à 11:16, Joseph Van Riper a écrit : > On Thu, Jun 2, 2016 at 6:09 PM Vicente J. Botet Escriba < > vicente.botet(a)wanadoo.fr> wrote: > >> 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? >> > Yes. At least for what we do where I work. > > The cyber-security field works with very old machines, either for forensics > (people forget they have some old machine until it gets hacked and some old > process that always "just worked" stops working), teaching (teaching old, > outmoded techniques helps to illustrate cyber security problems without > giving people tools for modern exploitation), or competitions. > > I kind of hate having to work with clunky, antediluvian C++ compilers that > magnify the level of woe required to deal with old machinery. Especially > while the rest of the C++ world moves on to the spiffy-shiny features found > in the later compilers. Having at least a library that helps us use some > of those nifty features can help us use our skills on more modern projects > when we move on to another job, while easing the efforts required to do our > work. A library wouldn't change your compiler ;-), but it could change the way you program :). > > 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? > > Hmmm... am I even knowledgeable enough? > > While I may find myself learning quite a lot about C++ by studying the > boost code people write, I am also humbled by what I see there. I fear I > am only beginning to dip into some of the intermediate meta-programming > techniques that seem to confer tremendous power to this language. > > as a Boost community project? >> outside Boost, as an independent project? >> > Hmmm... > > The boost 'brand' confers a certain gravitas. If you wish to maintain this > gravitas in the new library, I'd say keep the boost brand, but require the > same rigor. We have a License issue, so it couldn't be a Boost library :( Vicente P.S. Please, contact me privately if you are interested.

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[BGL] breadth_first_search with distance record and predecessors?
by The Maschine 06 Jun '16

06 Jun '16

Hi all, Im trying to cover the dijkstra_shortest_paths call I usually do with a BFS. Id like to get back the predecessors so I can rebuild the paths and the distance to each vertex. The dijkstra_shortest_paths work for me fine! I tried a couple of BFS calls but I always get errors. What am I missing? std::vector<Vertex> predecessors(boost::num_vertices(m_ugraph)); // To store parents std::vector<Weight> distances(boost::num_vertices(m_ugraph), std::numeric_limits<double>::max() ); // To store distances IndexMap indexMap = boost::get(boost::vertex_index, m_ugraph); PredecessorMap predecessorMap(&predecessors[0], indexMap); DistanceMap distanceMap(&distances[0], indexMap); boost::dijkstra_shortest_paths(m_ugraph, s_vertex, boost::predecessor_map(predecessorMap).distance_map(distanceMap).weight_map(boost::get(&EdgeProperties::m_weight, m_ugraph)) ); //breadth_first_search(m_ugraph, s_vertex, visitor( make_bfs_visitor( record_predecessors( &predecessors, on_tree_edge() ) ) ).vertex_index_map( identity_property_map() ).record_distances(&distances.begin(),boost::on_tree_edge()) ); //boost::breadth_first_search(m_ugraph, s_vertex, boost::visitor(boost::make_bfs_visitor(std::make_pair(boost::record_distances(&distances.begin(),boost::on_tree_edge()),boost::record_predecessors(&predecessors.begin(),boost::on_tree_edge{}))))); Thanks a lot!

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Boost.Fiber mini-review May 23 - June 1: review report
by Nat Goodspeed 06 Jun '16

06 Jun '16

The Boost.Fiber mini-review is now closed. Results: Bjorn Reese: YES Niall Douglas (private): YES Agustín K-ballo Bergé: YES Niall Douglas reminds me that in a previous mini-review he already voted to accept the Fiber library. Unless he stated that he had changed his mind, it would be reasonable to carry forward that "yes" vote. However, he did reaffirm his previous stance. In that spirit, let me remind the community of another couple previous positive votes: Eugene Yakubovich Antony Polukhin Significantly, there were no remaining NO votes. I therefore conclude that the Boost community ACCEPTS the Fiber library into the Boost family of libraries. On behalf of the Boost community, I would like to congratulate Oliver Kowalke not only for his engineering work, but for considerable patience in working to improve the library and its documentation. Thank you, Oliver!

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Boost fusion problem
by Jess Morecroft 05 Jun '16

05 Jun '16

Hi guys, We're trying out the latest version of Boost (1.61, migrating from 1.55) and have some code calling the fusion library that now doesn't compile and it's not obvious (to me at least) why. I've created a simple program (below) to demonstrate the issue. As per the compile/run section below, this compiles and runs with Boost 1.55, not with 1.61. If anyone has any idea or pointers to what is wrong here I'd really appreciate it. Sorry if this isn't the right forum for this kind of issue too - if so please let me know how best to seek help on this. Regards Jess ******************** main.cpp #include <boost/fusion/algorithm/iteration/for_each.hpp> #include <boost/fusion/view/zip_view.hpp> #include <boost/fusion/tuple.hpp> #include <iostream> #include <string> struct Helper { template<typename Arg> void operator()(const Arg& arg) const { std::cout << boost::fusion::get<0>(arg) << std::endl; std::cout << boost::fusion::get<1>(arg) << std::endl; } }; int main() { const int myint(123); const double mydub(456.0); const std::string mystr("blah"); const bool mybool(false); typedef boost::fusion::tuple<const int&, const double&> Tuple1; typedef boost::fusion::tuple<const std::string&, const bool&> Tuple2; typedef boost::fusion::tuple<const Tuple1&, const Tuple2&> Tuple3; Helper helper; boost::fusion::for_each( boost::fusion::zip_view<Tuple3>( Tuple3(Tuple1(myint, mydub), Tuple2(mystr, mybool))), helper); return 0; } ******************** compile/run tests jess@flathead:~$ g++ --version g++ (Ubuntu 5.3.1-14ubuntu2) 5.3.1 20160413 Copyright (C) 2015 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. (boost 1.55) jess@flathead:~$ g++ -std=c++14 main.cpp jess@flathead:~$ ./a.out 123 blah 456 0 (boost 1.61) jess@flathead:~$ g++ -std=c++14 main.cpp In file included from /usr/local/include/boost/fusion/container/vector/vector10.hpp:25:0, from /usr/local/include/boost/fusion/view/transform_view/transform_view.hpp:22, from /usr/local/include/boost/fusion/algorithm/transformation/transform.hpp:11, from /usr/local/include/boost/fusion/view/zip_view/detail/begin_impl.hpp:14, from /usr/local/include/boost/fusion/view/zip_view/zip_view.hpp:16, from /usr/local/include/boost/fusion/view/zip_view.hpp:12, from main.cpp:2: /usr/local/include/boost/fusion/container/vector/vector.hpp: In instantiation of ‘constexpr boost::fusion::vector_detail::vector_data<std::integer_sequence<long unsigned int, _Idx ...>, T ...>::vector_data(boost::fusion::vector_detail::each_elem, U&& ...) [with U = {const boost::fusion::tuple<const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&>&}; long unsigned int ...I = {0ul, 1ul}; T = {const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&}]’: /usr/local/include/boost/fusion/container/vector/vector.hpp:305:97: required from ‘boost::fusion::vector<T>::vector(U&& ...) [with U = {const boost::fusion::tuple<const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&>&}; T = {const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&}]’ /usr/local/include/boost/fusion/view/zip_view/zip_view.hpp:128:30: required from ‘constexpr boost::fusion::zip_view<Sequences>::zip_view(const Sequences&) [with Sequences = boost::fusion::tuple<const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&>]’ main.cpp:32:64: required from here /usr/local/include/boost/fusion/container/vector/vector.hpp:230:52: error: mismatched argument pack lengths while expanding ‘boost::fusion::vector_detail::store<I, T>’ : store<I, T>(std::forward<U>(var))... ^ /usr/local/include/boost/fusion/container/vector/vector.hpp: In instantiation of ‘constexpr boost::fusion::vector_detail::store<<anonymous>, T>::store() [with long unsigned int <anonymous> = 0ul; T = const boost::fusion::tuple<const int&, const double&>&]’: /usr/local/include/boost/fusion/container/vector/vector.hpp:230:52: required from ‘constexpr boost::fusion::vector_detail::vector_data<std::integer_sequence<long unsigned int, _Idx ...>, T ...>::vector_data(boost::fusion::vector_detail::each_elem, U&& ...) [with U = {const boost::fusion::tuple<const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&>&}; long unsigned int ...I = {0ul, 1ul}; T = {const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&}]’ /usr/local/include/boost/fusion/container/vector/vector.hpp:305:97: required from ‘boost::fusion::vector<T>::vector(U&& ...) [with U = {const boost::fusion::tuple<const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&>&}; T = {const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&}]’ /usr/local/include/boost/fusion/view/zip_view/zip_view.hpp:128:30: required from ‘constexpr boost::fusion::zip_view<Sequences>::zip_view(const Sequences&) [with Sequences = boost::fusion::tuple<const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&>]’ main.cpp:32:64: required from here /usr/local/include/boost/fusion/container/vector/vector.hpp:137:24: error: value-initialization of reference type ‘const boost::fusion::tuple<const int&, const double&>&’ : elem() // value-initialized explicitly ^ /usr/local/include/boost/fusion/container/vector/vector.hpp: In instantiation of ‘constexpr boost::fusion::vector_detail::store<<anonymous>, T>::store() [with long unsigned int <anonymous> = 1ul; T = const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&]’: /usr/local/include/boost/fusion/container/vector/vector.hpp:230:52: required from ‘constexpr boost::fusion::vector_detail::vector_data<std::integer_sequence<long unsigned int, _Idx ...>, T ...>::vector_data(boost::fusion::vector_detail::each_elem, U&& ...) [with U = {const boost::fusion::tuple<const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&>&}; long unsigned int ...I = {0ul, 1ul}; T = {const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&}]’ /usr/local/include/boost/fusion/container/vector/vector.hpp:305:97: required from ‘boost::fusion::vector<T>::vector(U&& ...) [with U = {const boost::fusion::tuple<const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&>&}; T = {const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&}]’ /usr/local/include/boost/fusion/view/zip_view/zip_view.hpp:128:30: required from ‘constexpr boost::fusion::zip_view<Sequences>::zip_view(const Sequences&) [with Sequences = boost::fusion::tuple<const boost::fusion::tuple<const int&, const double&>&, const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&>]’ main.cpp:32:64: required from here /usr/local/include/boost/fusion/container/vector/vector.hpp:137:24: error: value-initialization of reference type ‘const boost::fusion::tuple<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const bool&>&’

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Re: [Boost-users] [boost] 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

Le 03/06/2016 à 01:35, Edward Diener a écrit : > On 6/2/2016 6:09 PM, Vicente J. Botet Escriba wrote: >> 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? > > Most C++11 libraries have a Boost equivalent. In that case you could > either use the Boost library equivalent with your C++98 compiler or > use CXXD so that when you upgraded to a C++11 compiler you would not > have to change your code. CXXD would not ensure an almost compliant standard library. CXXD could be used to choose between this new library (scope C++11, implementation C++98) and the C++11 standard one. > So I assume you are talking about a C++11 library that does not have a > Boost equivalent. In which case what C++11/14/17 standard library are > you interested in forking ? No I was talking about the whole C++11 standard library. Vicente

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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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