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boost variant is not a literal type
by Robert Ramey 07 Jan '16

07 Jan '16

I want to use Boost.Variant constexpr function. In order to do this it has to be a literal type - which apparently it isn't. The rule for being a literal type are summarized here: http://en.cppreference.com/w/cpp/concept/LiteralType a boost::variant isn't default constructable so it fails to qualify. Has anyone else had this problem before and managed to solve it in a convenient way? Robert Ramey

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Re: [Boost-users] boost program options
by avib369 . 07 Jan '16

07 Jan '16

With reference to boost 1.59 and program options. The following test passes on boost 1.53, but fails on boost 1.59. I need to able to handle. --arg1 10 and --arg1=10 boost 1.59 now fails on '--arg1 10', with test below with option value being empty. #include <string> #include <iostream> #include <fstream> #include <boost/test/unit_test.hpp> #include <boost/foreach.hpp> #include <boost/program_options.hpp> using namespace std; namespace po = boost::program_options; BOOST_AUTO_TEST_SUITE( BaseTestSuite ) BOOST_AUTO_TEST_CASE( test_program_options_implicit_value ) { cout << "Base:: ...test_program_options_implicit_value\n"; // Declare the supported options. po::options_description desc("Allowed options"); desc.add_options() ("help", "produce help message") ("arg1", po::value<string>()->implicit_value( string("") ), "optional arg1 description") ; { char* argv[] = { const_cast<char*>("test_program_options_implicit_value"), const_cast<char*>("--help"), const_cast<char*>("--arg1") }; po::variables_map vm; po::store(po::parse_command_line(3, argv, desc), vm); po::notify(vm); BOOST_CHECK_MESSAGE(vm.count("help"), "Expected help"); BOOST_CHECK_MESSAGE(vm.count("arg1"), "Expected arg1"); BOOST_CHECK_MESSAGE(vm["arg1"].as<string>() == "", "Expected arg1 to be empty"); } { // ****** This fails on boost 1.59 bit passes in boost 1.53 ******* char* argv[] = { const_cast<char*>("test_program_options_implicit_value"), const_cast<char*>("--arg1"), const_cast<char*>("10") }; po::variables_map vm; po::store(po::command_line_parser(3, argv, desc), vm); po::notify(vm); BOOST_CHECK_MESSAGE(vm.count("arg1"), "Expected arg1"); BOOST_CHECK_MESSAGE(vm["arg1"].as<string>() == "10", "Expected arg1 with value of 10 but found '" << vm["arg1"].as<string>() << "'"); } { char* argv[] = { const_cast<char*>("test_program_options_implicit_value"), const_cast<char*>("--arg1=11") }; po::variables_map vm; po::store(po::parse_command_line(2, argv, desc), vm); po::notify(vm); BOOST_CHECK_MESSAGE(vm.count("arg1"), "Expected arg1"); BOOST_CHECK_MESSAGE(vm["arg1"].as<string>() == "11", "Expected arg1 with value of 11 but found " << vm["arg1"].as<string>()); } } Ta, Avi

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boost program_options
by avib369 . 07 Jan '16

07 Jan '16

There seems to be change/regression in boost program options. In boost/1.53. I used boost::program_options::variables_map vm; po::store( po::parse_command_line( argc, argv, desc_ , po::command_line_style::unix_style ^ po::command_line_style::allow_short), vm ); po::notify( vm ); This could handle arguments like: ./exe --help all ./exe --help summary However from boost 1.59, this no longer works, instead I have to use: ./exe --help=all ./exe --help=summary Is this a known change ? how do i get back to the old functionality ? Ta, Avi

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Boost 1.60.0 breaks Boost.Log formatter on MSVC11
by Robert Rumpf 07 Jan '16

07 Jan '16

I’ve been happily using Boost.Log (and much of the rest of Boost) for years, but on upgrading to 1.60, I find that I get runtime errors on MSVC 11. I’ve tracked the problem back to a simple representative example (as provided with the Boost.Log library): http://www.boost.org/doc/libs/1_60_0/libs/log/example/doc/tutorial_fmt_stre… The problematic portion of the example is the usage of character arrays when setting up the formatter, specifically: << ": <" << "> " The code compiles fine but then throws an exception at runtime, seemingly due to uninitialized data. Removing the strings in the formatter configuration makes the error disappear. I would guess that it has something to do with xvalues going into the formatter unintentionally, but this code has functioned fine on prior versions of Boost 1.59-1.54, and I can find nothing in the release notes that points me at where the problem might be. I am compiling with BOOST_SPIRIT_USE_PHOENIX_V3. Before I start doing lots of diffs, has anyone else experienced this problem, and is there any known solution or workaround? Thanks for all of the excellent work and support, Rob

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[regex] link errors on 1.60 update
by James Walker 07 Jan '16

07 Jan '16

When I tried to convert my project from Boost 1.58.0 to 1.60.0, I got some link errors. This is using Xcode 4.6.3 on Mac OS X 10.7.5. I'm compiling all the sources in libs/regex/src. Help? Undefined symbols for architecture i386: "boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::construct_init(boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags)", referenced from: boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::perl_matcher(char const*, char const*, boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags, char const*) in BVHJointMap.o boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::perl_matcher(char const*, char const*, boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags, char const*) in AnimationsManager.o "boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::find()", referenced from: bool boost::regex_search<char const*, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(char const*, char const*, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags) in BVHJointMap.o "boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::match()", referenced from: bool boost::regex_match<char const*, std::allocator<boost::sub_match<char const*> >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(char const*, char const*, boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags) in AnimationsManager.o

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Boost 1.60.0 rc1 is now available
by Marshall Clow 06 Jan '16

06 Jan '16

Release candidate files for 1.60.0 are available at: http://boost.cowic.de/rc/ As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. This helps ensure the candidates build OK before we push them out to SourceForge. The files (and associated md5s) are: MD5 (boost_1_60_0_rc1.7z) = 7ce7f5a4e396484da8da6b60d4ed7661 MD5 (boost_1_60_0_rc1.tar.bz2) = 65a840e1a0b13a558ff19eeb2c4f0cbe MD5 (boost_1_60_0_rc1.tar.gz) = 28f58b9a33469388302110562bdf6188 MD5 (boost_1_60_0_rc1.zip) = 0cc5b9cf9ccdf26945b225c7338b4288 Thanks! -- The release managers P.S. Release notes are here: http://www.boost.org/users/history/version_1_60_0.html

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C++Now 2106 Call for Submission
by Jon Kalb 05 Jan '16

05 Jan '16

Boost Users, The Call for Submissions for C++Now 2016 (AKA BoostCon) has been released: http://cppnow.org/2016-conference/announcements/2015/11/17/call-for-submissi on.html The deadline for submitting is very near and cannot be extended, so don¹t delay your submission. The conference will be held in Aspen the week of May 9th. See you in Aspen! Jon

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[boost][review][qvm] QVM formal review result
by Adam Wulkiewicz 05 Jan '16

05 Jan '16

Dear Boost community, The review period for Emil Dotchevski's QVM library has concluded. I'd like to thank everyone who participated in the discussions, esspecially those who sent formal reviews. Only four votes were casted however more people commented on issues on the mailing list. Comments received during the course of the review were generally positive, with a number of technical issues identified that need to be addressed. The review identified no fundamental problems in the design or implementation of the library that would entail rejection. The final version of the library can be fully accepted once Emil has addressed the issues identified during the review. Therefore I'm happy to say: Emil Dotchevski's Boost.QVM library is CONDITIONALLY ACCEPTED. Full report can be found here: http://lists.boost.org/Archives/boost/2016/01/227027.php Regards, Adam

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[Boost::Python]
by Eugenio Bargiacchi 04 Jan '16

04 Jan '16

Hello everyone, I have a member function with signature const Matrix2D & foo const (); Which returns an internal data structure. Matrix2D is using Matrix2D = Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor | Eigen::AutoAlign>; I have explicitly set a to_python converter for Matrix2D, and I have exported the function with a call policy of return_internal_reference. However, when this function is called from Python I get TypeError: No Python class registered for C++ class Eigen::Matrix<double, -1, -1, 1, -1, -1> This happens also if the reference is not const. At the same time, if I modify the call policy to return_value_policy<copy_const_reference>() Python can decode the matrix just fine. The same holds true if I return the Matrix2D by value. However I really need to have a reference to the matrix in order store it into other classes. How can I make Python see the data structure through the reference? The converter in case it is needed: boost::python::list toPythonList(const double * data, size_t num) { boost::python::list list; for (size_t i = 0; i < num; ++i) list.append(data[i]); return list;} struct Matrix2DToPython{ static PyObject* convert(Matrix2D const & m) { boost::python::list list; for (int i = 0; i < m.rows(); ++i) { list.append(toPythonList(m.row(i).data(), m.cols())); } return boost::python::incref(list.ptr()); }}; Thanks, Eugenio

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[units] Adding two absolute units
by Itzik 03 Jan '16

03 Jan '16

Hello, <obligatory appreciation on first post> I started using Boost just for boost::units and I find new ways boost can help me almost every day. So thanks for the great stuff! </obligatory appreciation on first post> My question to the board is why two absolute quantities (si::temperature (K) in my case) can't be summed in boost::units? I realized that this is a rule enforced by-design (gmane.comp.lib.boost.user/71747), and I understand that it is probably not a very common case, but I wanted my code to solve a simple formula which requires adding up two absolute temperatures (quantity<absolute<temperature>>). Each temperature represents an Inlet temperature in a Heat Exchange system. So even if converting one temperature to a relative type (quantity<temperature>) might be a workaround, it seems like a forced misuse to me. Eventually it turned out that I was mistaken with the formula, and subtraction was required instead, so there's no problem there. Alas, there's also a much simpler use case: What if I want to average the temperature of the last N readouts? Shouldn't boost::units support this simple operation? I have no formal physics education, but intuitively, adding two absolute temperatures doesn't seem really like a mistake to me, even if it's an odd thing to do. Will appreciate your thoughts on the matter.

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