October 2018 - Boost-users - lists.preview.boost.org

[interprocess] Determine size of managed_shared_memory
by Kai Benndorf 12 Oct '19

12 Oct '19

Hi all, I want to create a managed_shared_memory in exactly the size I needed. Therefore I do something like this: size = sizeof( common_managed_shared_memory ); size += sizeof( MyClassInSharedMem ); managed_shared_memory segment(create_only, "name", size ); MyClassInSharedMem allocates itself some memory by segment->allocate(). I added this also to the size, but get a boost::interprocess::bad_alloc exception on allocating this additional memory. Are there some magic bytes I forgot to add? Many thanks in advance Kai

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boost::filtered_graph filtering on vertex color... if I only had a colormap
by Brian Davis 19 Jul '19

19 Jul '19

Lets say I have a graph g (of type graph_t) and a color map (boy I wish I had a colormap): typedef boost::property_map<graph_t, boost::vertex_color_t>::type color_map_t; or is it? auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::default_color_type>(indexmap); or maybe? auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::vertex_color_t>(indexmap); or possibly some goop found on the internet? boost::make_iterator_property_map(color_map.begin(), boost::get(boost::vertex_index, data_->g), color_map[0]) or other internet goop? typedef boost::property_map<GraphType, boost::vertex_color_t>::type color_map_t; color_map_t colorMap; boost::color_map(colorMap)) or other internet goop?? std::vector<int> colorMap(num_vertices(g), boost::white_color); so confused... (certainly not surprised why bgl is not a part of stl) Can someone help explain the various types and ways of specifying colormaps and the logic for each way and means? and a function (if I could get that far without VS syntax highlighter going bonkers and gobs of compiler errors.. you know the type): make_pretty(g, colormap ) which colors the graph colormap and a filter struct for boost::filtered_graph<Graph, EdgePredicate, VertexPredicate> (where I wonder why if I only want to filter vertices I have to set boost::keep_all for EdgePredicate... sigh... I know the answer... and also know how long it found me to find/figure out boost::keep_all - and if you are looking for boost::keep_all and found it here... your welcome ;-) ) and modifying (probably incorrectly) boost::filtered_graph example to: template <typename ColorMap> struct vertex_color_filter_eq { vertex_color_filter_eq() { } vertex_color_filter_eq(ColorMap colormap/*, boost::default_color_type c*/) : m_colormap(colormap)/*, m_c(c)*/ { } template <typename Vertex> bool operator()(const Vertex& v) const { return 0 < get(m_colormap, v); //return c < get(m_colormap, v); } ColorMap m_colormap; //boost::default_color_type m_c; }; auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::default_color_type>(indexmap); // some where here I would call make_pretty(g, colors) typedef property_map<graph_t, boost::vertex_color_t>::type ColorMap_t; vertex_color_filter<ColorMap_t> filter(colors); // boost::filtered_graph<graph_t, boost::keep_all, VertexPredicate> boost::filtered_graph<graph_t, boost::keep_all, vertex_color_filter> fg(g, filter); // Later say if I could get it compile and better if it compiled and worked I could move on and auto color = boost::red_color; typedef property_map<graph_t, boost::vertex_color_t>::type ColorMap_t; vertex_color_filter<ColorMap_t> filter(colors, color); boost::filtered_graph<graph_t, boost::keep_all, vertex_color_filter> fg(g, filter); Maybe if I color them yellow, I can then reach the wizard pull back the curtain and ask how to create a color map... If I only had a color map.

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[boost.test] Colors
by Udo Steinbach 20 Feb '19

20 Feb '19

Ahoi! I use boost.test and have now updated to boost v1.68 on Windows, working in standard console. Now Test has colored output, YEAH. The result you see in the picture https://www2.pic-upload.de/img/36193998/no_error_detected.png Notice that I don't use the standard color scheme. With set BOOST_TEST_COLOR_OUTPUT=1 text is light green on gray, bad to read. set BOOST_TEST_COLOR_OUTPUT=0 does black on gray. After that the colors are set to my scheme. Now error result with set BOOST_TEST_COLOR_OUTPUT=1: https://www2.pic-upload.de/img/36193997/failure.png Light red on gray, OK to read, but reset to dark red on gray. I have to use the color command to reset the colors. With command line options it's all the same. Hmmm, how useful can colors be, if the standard output (no error detected) is only one short line? Both pics on https://www.pic-upload.de/gal-1197957/om664y/1.html -- Fahrradverkehr in Deutschland: http://radwege.udoline.de/ GPG: A245 F153 0636 6E34 E2F3 E1EB 817A B14D 3E7E 482E

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Web based C++ compiler with Boost support
by Michael Powell 01 Nov '18

01 Nov '18

Hello, Does anyone happen to know of a decent web based C++ compiler with Boost support? Specifics, if possibly, include support for MSVC, especially VS2017 C++, Spirit, probably C++17 as well, etc. I know that's probably asking for a lot, but my searches aren't turning up very much, or it is getting confused with literally "building Boost", which is a bit OT. :-) Thanks! Best regards, Michael Powell

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Roughed in Proto2 Spirit parser
by Michael Powell 31 Oct '18

31 Oct '18

Hello, I'm working on a Proto2 Spirit parser. Right now it's really roughed in. There is no AST at the moment. That's TBD; right now I am focused on just getting the build to work. https://gcc.godbolt.org/z/_nBsKi The code is there, but the compiler driving the web site is choking on Spirit. I put the rules in up front; probably ambitious on my part, and am finding an error on: _range %= _int_lit >> -(lit("to") >> (_int_lit | lit("max")); Severity Code Description Project File Line Suppression State Error C1075 '{': no matching token found Kingdom.OrTools.Sat.Params.Generator g:\source\kingdom software\kingdom.ortools\standard\src\kingdom.ortools.sat.params.generator\proto_parser.cpp 205 The Proto2 grammar states: range = intLit [ "to" ( intLit | "max" ) ] I'm considering pairing it back significantly and building the grammar up gradually to make sure it all builds. That's probably a sounder approach anyway. Eventually I want to build up the AST in such a way as to facilitate generating some boilerplate adapter code in my target language (C#). Thoughts? Best regards, Michael Powell https://developers.google.com/protocol-buffers/docs/reference/proto2-spec

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Error building Spirit parser in VS2017
by Michael Powell 31 Oct '18

31 Oct '18

Hello, I am receiving the following error building against the latest VS2017 ... 1>Version_Parser.cpp 1>d:\dev\boost.org\boost_1_68_0\boost\iostreams\positioning.hpp(96): error C4996: 'std::fpos<_Mbstatet>::seekpos': warning STL4019: The member std::fpos::seekpos() is non-Standard, and is preserved only for compatibility with workarounds for old versions of Visual C++. It will be removed in a future release, and in this release always returns 0. Please use standards-conforming mechanisms to manipulate fpos, such as conversions to and from streamoff, or an integral type, instead. If you are receiving this message while compiling Boost.IOStreams, a fix has been submitted upstream to make Boost use standards-conforming mechanisms, as it does for other compilers. You can define _SILENCE_FPOS_SEEKPOS_DEPRECATION_WARNING to acknowledge that you have received this warning, or define _REMOVE_FPOS_SEEKPOS to remove std::fpos::seekpos entirely. 1>c:\program files (x86)\microsoft visual studio\2017\enterprise\vc\tools\msvc\14.15.26726\include\iosfwd(59): note: see declaration of 'std::fpos<_Mbstatet>::seekpos' With my grammar: BOOST_FUSION_ADAPT_STRUCT(NS_VERSION_H::version, _major, _minor, _patch, _build); template <typename It> struct version_parser : qi::grammar<It, NS_VERSION_H::version()> { version_parser() : dot_('.'), version_parser::base_type(_start) { using qi::lit; using qi::hold; using qi::short_; _major_part = short_; _minor_part = lit(dot_) >> short_; _patch_part = lit(dot_) >> short_; _build_part = lit(dot_) >> short_; _start = hold[_major_part >> _minor_part >> -(_patch_part >> -_build_part)]; } private: qi::rule<It, NS_VERSION_H::version()> _start; const char dot_; qi::rule<It, short()> _major_part; qi::rule<It, short()> _minor_part; qi::rule<It, short()> _patch_part; qi::rule<It, short()> _build_part; }; bool try_parse_version(const std::string& s, NS_VERSION_H::version& v) { using It = std::string::const_iterator; using qi::parse; It first = s.begin(), last = s.end(); if (!parse(first, last, version_parser<It>{}, v)) { std::cout << "Failed to parse: '" << s << "'" << std::endl; return false; } const auto dot_ = "."; std::cout << "version: " << v._major << dot_ << v._minor << dot_ << v._patch << dot_ << v._build << std::endl; return true; } At present I have not furnished any Spirit flags or anything of that sort; pretty much taking the includes, grammar, building as-is. Secondary to the error, I want the parser to reject spaces, should just be numeric (short) and the dot delimiter. Best regards, Michael Powell

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Boost "Application" concept?
by Michael Powell 30 Oct '18

30 Oct '18

Hello, I know Boost has within its repo the elements of bits that comprise a typical application; i.e. program options, for starters, etc. However, I was curious, is there a library in the Boost repo that wraps it all up in a prescribed format? Or a handle of recipes? Things I would expect to find include the program options, ability to run, with some arguments, etc. Not an exhaustive set of expectations, to be sure. Thanks for the feedback! Cheers, Michael W Powell

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Boost 1.68.0 - boost hashing changed ?
by Shailja Prasad 28 Oct '18

28 Oct '18

Hello there, I was trying to upgrade boost 1.53.0 to boost 1.68.0. But, it looks like hashing code generation has changed, since the following line gives two different hashcode for same string input. boost::hash<string> namehash; size_t hashCode = namehash( name); Where name is string, an e.g “abcdefg” With boost 1.53.0 the hashCode is 168904 And with boost 1.68.0 the hashCode is 69530. I am giving just sample random number here, those two numbers are never equal, with everything remain the same, only change boost version on EL6 Linux machine with GCC 4.9 compiler. This is blocking me to upgrade to newer version of boost. I appreciate if anyone has some info on this. Thanks

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Mailman upgrade
by Brad Johnson 27 Oct '18

27 Oct '18

Happy Late October all. Just a quick notification that mailman upgraded from 2.1.26 -> 2.1.29 at 27-Oct-2018 02:50 UTC. Release notes for 2.1.27, 2.1.28, and 2.1.29: https://launchpad.net/mailman/2.1/2.1.27 https://launchpad.net/mailman/2.1/2.1.28 https://launchpad.net/mailman/2.1/2.1.29 Sanity checks on test mailing list shows mail is still flowing and archiving. Any questions or concerns, please let me know at this address or sysadmin(a)boost.org. Thanks, -- Brad Johnson Ciere Consulting 916.877.6030 brad.johnson(a)ciere.com ciere.com

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Boost Multiprecision list.
by A Z 26 Oct '18

26 Oct '18

I am aware the the boost multiprecision library is a headers library. -Is Boost multiprecision accurately arbitrary precision, ie. can have its number precisions and scales always made to a larger number, contingent only to the amount of available OS memory? -If I want to use boost Boost multiprecision on its own, what is the name of the Boost .dll or .lib files that have all the headers in it? I need a minimal set of files in order to run multiprecision on its own. ?

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