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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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