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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Boost iterator facade implementation
by rmawatson rmawatson 26 Oct '18

26 Oct '18

https://github.com/boostorg/iterator/blob/boost-1.63.0/include/boost/iterat… I was wondering about is_non_proxy_reference<Reference,Value> in this metafunction. It appears to select between postfix_increment_proxy<Iterator> and writable_postfix_increment_proxy<Iterator> based on whether Reference is the same type as Value ignoring cv& what is the case that writable_postfix_increment_proxy<Iterator> is selected. So when is Reference going to be a different 'base type' to Value? is this to support user returning their own proxy or something?

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[asio] Advice on implementing rate-limiting for async_write
by Kyle Ketterer 25 Oct '18

25 Oct '18

Hello fellow Boost friends, I am looking into some advice on implementing rate-limiting using using Boost ASIO with async_write. I am working on a Enterprise File Backup solution named Vessel @ https://github.com/VesselEnterprise/vessel-backup. My project uses Boost through and through. The use case is as follows: - Many users on the same network/subnet may be transferring files at once - I want to add the feature of being able to limit upload speed to the storage provider (AWS, Azure, etc) The request starts as follows: (pseudo code) Let's say we have a string of 1000 bytes we want to send to a server: const std::string& request //Passed to member function and make_shared<>() > to member var on stack to ensure lifetime of async operation Let's also say we want to limit the transfer speed to 100 bytes/second size_t transfer_max = 100; Should we start the request with async_write() on the socket? //Ensure that no more than transfer_max bytes are sent during the first write > boost::asio::async_write(*m_socket, boost::asio::buffer(http_request, > transfer_max), boost::bind(&HttpClient::handle_write, this, > boost::asio::placeholders::error, > boost::asio::placeholders::bytes_transferred )) ; > Here is where I have questions. In the completion handler handle_write(...), we need to continue to call async_write() until all bytes have been written and determine the current transfer rate, and sleep the thread if necessary. When sending the next set of bytes, is it best to explicitly declare a buffer and consume or use a pointer to the char array? void HttpClient::handle_write( const boost::system::error_code& e, size_t > bytes_transferred ) > { > /** > ** Do some stuff here to determine transfer rate, and sleep if > necessary... > */ > > //Pseudocode > if ( transfer_rate > transfer_max ) > { > //Possibility 1? > auto buffer = boost::asio::buffer(request, transfer_max); > buffer.consume(total_bytes_transferred_so_far); > boost::asio::async_write(*m_socket, buffer, > boost::bind(&HttpClient::handle_write, this, > boost::asio::placeholders::error, > boost::asio::placeholders::bytes_transferred )) ; > //Possibility 2? > boost::asio::async_write(*m_socket, > boost::asio::buffer(&request[total_bytes_transferred_so_far], > transfer_max), boost::bind(&HttpClient::handle_write, this, > boost::asio::placeholders::error, > boost::asio::placeholders::bytes_transferred )) ; > return; > > } > //...eof > } Advice on the topic is greatly appreciated. If I am way off, just let me know :) Thanks! -- Kyle Ketterer <reminisc3(a)gmail.com>

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[gil] Who uses Boost.GIL?
by Mateusz Loskot 24 Oct '18

24 Oct '18

Dear Boost Users, I'm interested in collecting a list of software projects using or depending on, directly or indirectly, Boost.GIL. If you stick boost::gil anywhere in your code, please tell me about it, drop link to your project. I'd like to list users of GIL at https://github.com/boostorg/gil/wiki/Who-Uses-GIL If you ask me to not to, I'll respect your request. Thank you! Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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[release] 1.69.0 deadline for new libraries approaching
by Marshall Clow 22 Oct '18

22 Oct '18

It's that time again! On Wednesday, the master branch will be closed for adding new libraries. Upcoming dates: * 24-Oct: Boost 1.69.0 closed for new libraries and breaking changes * 31-Oct: Boost 1.69.0 closed for major code changes * 7-Nov: Boost 1.69.0 closed for beta * 14-Nov: Boost 1.69.0 beta 1 * 5-Dec: Boost 1.69.0 closed for release * 12-Dec: Boost 1.69.0 release -- The Boost Release Team

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[Range] Help with syntax
by Robert Jones 19 Oct '18

19 Oct '18

Given struct S { int i( ) const; }; vector<S> v; set<int> s; I want to write (approximately) for_each( v | transform( []( const S & s ){ return s.i( ); } ), s.emplace ); With the intention putting all the i's extracted from v into the set s. My syntax is all over the place, and I'm not sure how to express the s.emplace bit. Also is there a better way to say the whole thing? If I were doing push_back instead of emplace there's a facility especially for that, but I guess Boost::Range hasn't embraced emplace because range-v3 is around now. I'm sure some of you are fluent in this stuff! Kind Regards Rob.

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[Boost-serialization] undefined reference error
by phillip mobley 19 Oct '18

19 Oct '18

Hello all, I ma having a major issue with the boost library. I have been having this issue for a few days now and I can't seem to figure out what the problem is. Basically, I get this error message after my linker: "undefined reference to `boost::archive::text_oarchive_impl<boost::archive::text_oarchive>::save(std::string const&)'" My complete linker command is as follows: " -L. -L/usr/lib/x86_64-linux-gnu -L/usr/local/lib -L/usr/lib/lapack -lfreetype -lGLEW -llapack -lboost_serialization -lglut -lGL -lGLU -L/usr/local/lib -pthread -lwx_gtk2u_xrc-3.1 -lwx_gtk2u_stc-3.1 -lwx_gtk2u_richtext-3.1 -lwx_gtk2u_ribbon-3.1 -lwx_gtk2u_propgrid-3.1 -lwx_gtk2u_aui-3.1 -lwx_gtk2u_gl-3.1 -lwx_gtk2u_html-3.1 -lwx_gtk2u_qa-3.1 -lwx_gtk2u_adv-3.1 -lwx_gtk2u_core-3.1 -lwx_baseu_xml-3.1 -lwx_baseu_net-3.1 -lwx_baseu-3.1" I built Boost 1.64 from the source and kept the default values. I also built the whole library. My Boost library is built into the /usr/local folder. I am pretty sure that I am referencing the linker libraries correctly but I can't seem to figure out why I would be getting this error message. Has anyone had an issue similar to this before?

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[Boost.Serialization] Unnecessary use of <iostream> in boost/serialization/export.hpp
by dariomt＠gmail.com 18 Oct '18

18 Oct '18

Hi, I see #include <iostream> in header boost/serialization/export.hpp, but that header uses nothing from namespace std. To me it looks like that #include is unnecessary, as all my code compiles fine if I remove that #include, but maybe I'm wrong. Was it included by mistake? PS: I'm using Boost 1.64, but I see the same #include in Boost 1.68

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Questions about Boost multiprecision library.
by A Z 11 Oct '18

11 Oct '18

I have some basic startup for use questions pertaining to the Boost multiprecision library. I have downloaded the set of 64 bit .dll files successfully online, and would like some help points to help me get going. *I have heard that there are some strange results that can happen if you are quizzing multiprecision for trigonometry and try to keep using the double type. Is this true, so that I can just kee relying on the std library instead? -What is the name of the 64 bit windows .dll, or .dll files, that are the ones for the multiprecision library? -If I wish to go into arbitrary precision and scale numbers, what is the type I should use for an integer? What is the #include statement I should use, and how do I specify the number of whole number points and decimal points, before starting my operations? -If I wish to go into arbitrary precision and scale numbers, what is the type I should use for a rational number? What is the #include statement I should use, and how do I specify the number of whole number points and decimal points, before starting my operations? -For these two types, I wish to do sine, cosine, tangent, arcsine, arccosine, arctangent, base 10 logarithm, base e logarithm, power, nth root. I also want to obtain pi, but also Euler's constant, to any number of significang figure or decimal places that I would like. -If the files are separate for the function support or not, what are the 64 bit .dll files for this? What #include statements should I use?

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signals2
by tim＠raisedbar.net 04 Oct '18

04 Oct '18

Hi, A friend pointed me at this library, as it may solve a problem for me. Am I correct in thinking that a signal can be activated once all of its slots are filled and not before? Best wishes. Tim Burgess Raised Bar Ltd. E: <mailto:tim@raisedbar.net> tim(a)raisedbar.net M: +44 (0)7989 486976

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Twenty years and time to retire
by Beman Dawes 04 Oct '18

04 Oct '18

The idea behind Boost was hatched in March, 1998, and the proposal document <https://www.boost.org/users/proposal.pdf> was released May 6, 1998. That makes Boost twenty years old, and makes me twenty years older. It is high time I retire from Boost; I haven't been able to contribute for some time now. Thanks to all of you who made Boost such an overwhelming success in the past and will drive Boost forward into a bright future! --Beman

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Making interprocess::message_queue use Windows_shared_memory instead of shared_memory_object
by Gaurav Sehgal 04 Oct '18

04 Oct '18

Hi, I am trying to make boost::interprocess::message_queue to use windows_shared_memory, instead of shared_memory_object. I have made the below changes to boost version 1.65.1 1) In ipc\message_queue.hpp, included windows_shared_memory.hpp instead of shared_memory_object.hpp 2) Changed typedef ipcdetail::managed_open_or_create_impl<shared_memory_object, 0, true, false> open_create_impl_t; to typedef ipcdetail::managed_open_or_create_impl<windows_shared_memory, 0, false, false> open_create_impl_t; 3) Changed the below in mq_hdr_t:: typedef ipcdetail::managed_open_or_create_impl<shared_memory_object, 0, true, false> open_create_impl_t; to typedef ipcdetail::managed_open_or_create_impl<windows_shared_memory, 0, false, false> open_create_impl_t; 4) Changed inline bool message_queue_t<VoidPointer>::remove(const char *name) { return shared_memory_object::remove(name); } to inline bool message_queue_t<VoidPointer>::remove(const char *name) { return true; } 5)Changed the below in detail\managed_open_or_create_impl.hpp template<bool dummy> static void truncate_device(DeviceAbstraction &dev, offset_t size, true_) { dev.truncate(size); } to template<bool dummy> static void truncate_device(DeviceAbstraction &dev, offset_t size, true_) { } After the above changes, no file is getting created and everything seems to work. Is there something else i should care about? Regards, Gaurav.

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undefined reference to `boost::log::v2_mt_posix::...
by Antonis Polykratis 01 Oct '18

01 Oct '18

Hello I face this error and I cannot figure out a fix. I use bjam to build the application code, and inside site-config file, I have also the following a section where I define BOOST_ALL_DYN_LINK: ''' using gcc : : : where I have defined <define> BOOST_ALL_DYN_LINK ''' I have build boost libraries with the following command: sudo bjam toolset=gcc --with-system --with-thread --with-timer --with-chrono --with-filesystem --with-program_options --with-timer *--with-log* --with-program_options --with-date_time --with-math --with-serialization --with-regex --with-chrono --with-atomic runtime-link=shared define=*BOOST_ALL_DYN_LINK* --prefix=/opt/boost_shared install | tee output.txt I also changed some files (macro definitions and jam files) because I had an error that system and filesystem are configured to be compiled both as static and shared. I compiled them as shared. When I build the application code, I have plenty of `boost::log::v2_mt_posix::...` error messages. Could you give me some guide why this problem exist? Thanks, Antonis

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