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option to let program_options remove the flags it recognises
by Brice Rebsamen 14 Apr '16

14 Apr '16

I believe it would be good to add an option to program_options to tell it to remove the flags it recognizes. That would allow to make it work with some other parsers such as gflags etc.

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[property_tree] Json parser with invalid JSON string
by Sébastien Gallou 13 Apr '16

13 Apr '16

Hi all, I experience a strange behavior of parsing non-JSON data with JSON parser. I can create a property_tree from a simple non-JSON string, without exception. And serializing back the result throws : boost::property_tree::ptree m_tree; // Non-JSON to ptree using JSON parser std::istringstream is("1"); // Simple value, non-JSON boost::property_tree::json_parser::read_json(is, m_tree); // ==> No exception, I now have a valid ptree object. // ptree back to JSON std::ostringstream buf; boost::property_tree::json_parser::write_json(buf, m_tree, false); // ==> Exception How can I filter input values that will not be serializable later (= verify that input value is well JSON formatted) ? Thanks for your help, S. Gallou

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boost with c++11
by Christian Meesters 13 Apr '16

13 Apr '16

Dear All, Perhaps my question has been covered already, in this case a pointer to the relevant docs / thread would be highly appreciated. However, I have not been able to find the answer on my question: My code makes use of the C++11 standard and the standard libraries. I feel tempted to employ more current features, also beyond C++11, eventually. When downloading the boost 1.60.0 release and compiling with cxxflags='-std=c++11 -march=native' toolset=gcc linkflags=-stdlib=libc++ supplied to b2 compilation of my software (with gcc 5.3.0) leads to a number of warning messages and deprecation messages related to unused variables or redifined symbols, e.g.: - boost_1_60_0/include/boost/system/error_code.hpp:223:36: warning: ‘boost::system::native_ecat’ defined but not used [-Wunused-variable] static const error_category & native_ecat = system_category(); - /boost_1_60_0/include/boost/iostreams/chain.hpp:256:14: warning: ‘template<class> class std::auto_ptr’ is deprecated [-Wdeprecated-declarations] std::auto_ptr<streambuf_t> In file included from /cluster/gcc/5.3.0/include/c++/5.3.0/memory:81:0, from trunk/src/ngs_io.cpp:8: /cluster/gcc/5.3.0/include/c++/5.3.0/bits/unique_ptr.h:49:28: note: declared here template<typename> class auto_ptr; - /usr/include/boost/iostreams/detail/adapter/concept_adapter.hpp:35:7: note: ‘boost::iostreams::detail::concept_adapter<boost::iostreams::basic_gzip_decompressor<> >::concept_adapter(const boost::iostreams::detail::concept_adapter<boost::iostreams::basic_gzip_decompressor<> >&)’ is implicitly deleted because the default definition would be ill-formed: class concept_adapter { ^ etc. And most importantly this error: /usr/include/boost/iostreams/detail/adapter/concept_adapter.hpp:35:7: error: use of deleted function ‘boost::iostreams::basic_gzip_decompressor<>::basic_gzip_decompressor(const boost::iostreams::basic_gzip_decompressor<>&)’ My g++ compiler flags (other than output and source file) are: -c -fopenmp -O3 -march=native -Wall -ansi -pedantic -Wuninitialized -std=c++11 The code compiles fine with a git pull from May last year, yet I do not recall what I have done differently. So, can anybody tell me how to set up boost, such that compilation and linking against C++11 std-libraries works? I understand that Best regards, Christian Meesters

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Boost Log: I can't see syslog messages sent via boost syslog.
by Anatoly G 11 Apr '16

11 Apr '16

Dear members, I have a question about Boost syslog. I"m beginner Boost user. I created attached code and can't understand why it doesn't work. I execute my code on linux Kubuntu 3.13.0 After execution I"m looking for test strings in syslog file: grep "Test" /var/log/syslog But I don't see any line. I tried to execute commands from shell logger "Test from shell" logger -n 127.0.0.1 -t myapp -p user.notice "Test from shell" I see these lines after executing grep on /var/log/syslog I tried to initialize syslog_backend with boost::log::keywords::use_impl = boost::log::sinks::syslog::native instead of boost::log::keywords::use_impl = boost::log::sinks::syslog::udp_socket_based but then I get compile message, native not defined. I found BOOST_LOG_USE_NATIVE_SYSLOG macro which should be defined during Boost build, but I don't understand how to activate this macro in boost build. Can you please suggest what is the problem? Regards, Anatoly.

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[accumulators] nan error of mean
by Ireneusz Szcześniak 08 Apr '16

08 Apr '16

Hi, I'm using Boost.Accumulators to calculate the standard error of a sample mean, and I'm getting a nan (not a number) as a result, while I should be getting a zero or some number close to it. I boiled down the problem to a small sample that I'm attaching. I would appreciate it if someone could help me out here. Thanks, Irek

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[Boost.Container] flat_set constructor with ordered_unique_range
by dariomt＠gmail.com 08 Apr '16

08 Apr '16

Hi list, If I use the flat_set constructor passing ordered_unique_range, does the library assert in debug mode that the passed data range is indeed ordered and unique? I don't seem to find such assert, but I think it would be very useful, to catch programmer errors. Regards

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seekable input filter definition
by Cherotek Music 07 Apr '16

07 Apr '16

Hey, I'm new to boost and need a seekable input filter that will operate on bytes read from an ifstream. This is what I currently have: struct my_filter : boost::iostreams::seekable_filter{ template<typename Source> int get(Source& src) { int byte = boost::iostreams::get(src); if(byte != EOF && byte != boost::iostreams::WOULD_BLOCK) { // Do something with byte } return byte; } template<typename Sink> bool put(Sink&, char) { // No need to actually implement put because this filter is only used with ifstream return true; } template<typename T> std::streampos seek(T& t, boost::iostreams::stream_offset off, std::ios_base::seekdir way, std::ios_base::openmode which = std::ios_base::in | std::ios_base::out) { return boost::iostreams::seek(t, off, way, which); }}; It works but I would like to get rid of the useless put method. The boost documentation here http://www.boost.org/doc/libs/1_60_0/libs/iostreams/doc/concepts/filter.html says there is an InputSeekableFilter refinement of Filter but I can't seem to understand how to use it (there are no input_seekable_filter_tag or input_seekable_filter structs that I could use). Thanks

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[asio] Error code by io_service.run(ec) not the same as in async_read_handler
by Michael Weise 06 Apr '16

06 Apr '16

Hello, my question is about the error code returned by io_service.run_one. I expect the error code returned by run_one to be the same as the one in the handler - but they are not. Inside my handler I check the error code, which is equal to operation aborted: void ConnectionBase::ReadUntilHandler( const boost::system::error_code & ec, std::size_t bytes_transferred) { // ec == boost::asio::error::operation_aborted ... } At some other point I call io_service.run_one, which calls the above handler: ... m_asioService.run_one(ec); assert(ec == boost::asio::error::operation_aborted); ... The assertion fails - for some reason the error code is not the same as in the handler. What's the reason for this? Maybe my assumtion that run_one(ec) returns the error code of the handler is simply wrong? If so, what error does io_service.run(ec) actually report? Thanks for help, Michael PS: boost::asio version is 1.56.0

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Using Boost.ASIO with Boost.Coroutine2
by Carlos Ferreira 06 Apr '16

06 Apr '16

Hello to all! Is it possible to use Boost.ASIO with Boost.Coroutine2? For what I understood upon reading the documentation, using Boost.Corouine2 is preferable, due to issues present in Coroutine that were solved in Coroutine2. The documentation is scarse and I'm having some trouble in making things work. Thank you! -- Carlos Miguel Ferreira Researcher at Telecommunications Institute Aveiro - Portugal Work E-mail - cmf(a)av.it.pt Skype & GTalk -> carlosmf.pt(a)gmail.com LinkedIn -> http://www.linkedin.com/in/carlosmferreira

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[Q] piecewise_construct for boost::container::map::emplace()
by dave m. 05 Apr '16

05 Apr '16

I recently tried (but failed) to use boost::container::map::emplace() with the piecewise_construct tag to forward constructor args as tuples. After some fiddling around, it appears that piecewise_construct is not implemented for boost::container::detail::pair (see boost/container/detail/pair.hpp:151). I couldn't find any discussion in the mailing list archives. Is there a good reason not to use emplace() this way, or unreasonable difficulty in implementing piecewise_construct for pair<U,V>? (I ended up making constructors for my K, V elements that take tuples<>, so emplace() is working for me, but I'm not completely sure that I have avoided all possible copy/move operations. Using gcc-4.9.2, fwiw.) Thanks, dhm

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