March 2015 - Boost-users - lists.preview.boost.org

boost::property_tree::ptree with write_xml
by Uthpal Urubail 21 Mar '15

21 Mar '15

All, I am looking got the help with xml writer using property tree. My requirement is to write a user defined comment (in below example /*comment*/) in every line of XML file. Example: /*comment*/<debug> /*comment*/ <filename>debug.log</filename> /*comment*/ <modules> /*comment*/ <module>Finance</module> /*comment*/ <module>Admin</module> /*comment*/ <module>HR</module> /*comment*/ </modules> /*comment*/ <level>2</level> /*comment*/</debug> Can someone help me in solving the above? Any help on this would be highly appreciated. boost::property_tree::xml_writer_settings<std::string> w(' ', 4); write_xml(os, pt,w); Regards, UJ

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phoenix 1.55 no-arg mem function fails
by MM 20 Mar '15

20 Mar '15

#include <boost/phoenix/phoenix.hpp> struct Foo { const int& bar() const { return i; } int i; }; int main() { Foo f; const int& ir = boost::phoenix::bind(&Foo::bar, f)(); } The above fails to compile. linux g++492 -std=c++11 -c 1.cpp When bar() has a single int arg for e.g., boost::phoenix::bind(&Foo::bar, f, 5)(); succeeds. The error: In file included from /usr/include/boost/phoenix/bind/bind_member_variable.hpp:13:0, from /usr/include/boost/phoenix/bind.hpp:17, from /usr/include/boost/phoenix/phoenix.hpp:17, from 1.cpp:1: /usr/include/boost/phoenix/bind/detail/member_variable.hpp: In instantiation of ‘struct boost::phoenix::detail::member_variable<const int&() const, const int& (Foo::*)() const>’: /usr/include/boost/proto/make_expr.hpp:77:16: required from ‘struct boost::proto::detail::protoify<boost::phoenix::detail::member_variable<const int&() const, const int& (Foo::*)() const>, boost::proto::domainns_::basic_default_domain>’ /usr/include/boost/proto/detail/preprocessed/make_expr_.hpp:70:9: required from ‘struct boost::proto::detail::make_expr_<boost::phoenix::detail::tag::function_eval, boost::proto::domainns_::basic_default_domain, boost::phoenix::detail::member_variable<const int&() const, const int& (Foo::*)() const>, Foo, void, void, void, void, void, void, void, void, void>’ /usr/include/boost/proto/make_expr.hpp:185:13: required from ‘struct boost::proto::result_of::make_expr<boost::phoenix::detail::tag::function_eval, boost::proto::domainns_::basic_default_domain, boost::phoenix::detail::member_variable<const int&() const, const int& (Foo::*)() const>, Foo, void, void, void, void, void, void, void, void, void>’ /usr/include/boost/phoenix/core/preprocessed/expression_10.hpp:84:13: required from ‘struct boost::phoenix::expr_ext<boost::phoenix::actor, boost::phoenix::detail::tag::function_eval, boost::phoenix::detail::member_variable<const int&() const, const int& (Foo::*)() const>, Foo, void, void, void, void, void, void, void, void, void>’ /usr/include/boost/phoenix/core/preprocessed/expression_10.hpp:24:12: required from ‘struct boost::phoenix::expr<boost::phoenix::detail::tag::function_eval, boost::phoenix::detail::member_variable<const int&() const, const int& (Foo::*)() const>, Foo, void, void, void, void, void, void, void, void, void>’ /usr/include/boost/phoenix/core/detail/preprocessed/function_eval_10.hpp:7:561: required from ‘struct boost::phoenix::detail::expression::function_eval<boost::phoenix::detail::member_variable<const int&() const, const int& (Foo::*)() const>, Foo, void, void, void, void, void, void, void, void, void>’ /usr/include/boost/phoenix/bind/bind_member_variable.hpp:37:5: required by substitution of ‘template<class RT, class ClassT> const typename boost::phoenix::detail::expression::function_eval<boost::phoenix::detail::member_variable<RT, RT ClassT::*>, ClassT>::type boost::phoenix::bind(RT ClassT::*, ClassT&) [with RT = const int&() const; ClassT = Foo]’ 1.cpp:11:52: required from here /usr/include/boost/phoenix/bind/detail/member_variable.hpp:50:17: error: forming reference to qualified function type ‘const int&() const’ RT& operator()(Class& obj) const ^ /usr/include/boost/phoenix/bind/detail/member_variable.hpp:59:23: error: forming reference to qualified function type ‘const int&() const’ RT const& operator()(Class const& obj) const ^ /usr/include/boost/phoenix/bind/detail/member_variable.hpp:68:17: error: forming reference to qualified function type ‘const int&() const’ RT& operator()(Class* obj) const ^ /usr/include/boost/phoenix/bind/detail/member_variable.hpp:74:23: error: forming reference to qualified function type ‘const int&() const’ RT const& operator()(Class const* obj) const Rds,

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phoenix: c++11
by MM 20 Mar '15

20 Mar '15

Hello Are there plans to add emplace_back to the stl part of phoenix? MM

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what happens between "fixed in development" and "available in release"?
by oswin krause 20 Mar '15

20 Mar '15

Hi, Question is in the subject. What has to happen after a fix of a bug in development stage before it enters an official release? Do not get me wrong, I like boost and all it does for the community and all the effort people put into it. And i really would like to help to speed up certain...processes, but for this i have to know what can block this step? Apparently a bug in serialisation - which totally breaks my software to the point where it can not be compiled on several linux distributions und MacOsX since release of boost 1.56 - is fixed in development even prior to 1.57 and is still not available in 1.58. And what I hear from several mails across the mailing list, this is not the only change that got stuck. And somehow i have the feeling that the new boost release cycle won't make the situation any better. As I said, do not get me wrong, but this situation becomes unbearable as these boost versions spread more and more through the ecosystem and there is really nothing on my side I can do about it, except rolling my own implementation and maintaining it, until this whole thing is faded out of all major distributions(you might already get the feeling that I am not really happy about doing that). if there is something i can do to help, I will do it. But I now know that "report bugs and investigate possible fixes and send patches" does not necessarily lead to a fast fix and i am pretty frustrated by the situation. Best, Oswin

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[multi_index] iterating over keys and "extracting" key extractors
by Nick Stokes 20 Mar '15

20 Mar '15

Q1: Is there a builtin in way in MI to iterate over keys rather than elements? I.e. the iterator's value type will be that of the key, not the element. Q2: Is there a way to obtain the type of key extractors given a multi index container? (it is related to Q1, as this sort of a thing could be passed to boost::transform iterator to obtain an alternative answer for Q1) An example is in order: struct Foo { int id; sting name; }; using namespace boost::multi_index; typedef multi_index_container< Foo, indexed_by< ordered_unique< member< Foo, int, &Foo::id > >, ordered_unique< member< Foo, string, &Foo::name > > > MFoo; MFoo foos; // .. populate // Now, we want to iterate over sorted name's only, for e.g: auto beg = answer_to_Q1(foos).begin(); auto end = answer_to_Q1(foos).end(); std::copy( beg, end, ostream_iterator<string>(cout, " ") ); // Continuing the example for Q2: auto aFunctorThatExtractsFooName = answer_to_Q2<M>::type(); auto beg = make_transform_iterator( M.get<1>.cbegin(), aFunctorThatExtractsFooName ); auto end = make_transform_iterator( M.get<1>.cend(), aFunctorThatExtractsFooName ); std::copy( beg, end, ostream_iterator<string>(cout, " ") ); Thanks! Nick

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From: giridhar
by giridhar 19 Mar '15

19 Mar '15

Hello boost http://thalbangla.org/business.php?broken=6zpp82zkpkd1 giridhar Sent from my iPhone

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[afio][v1.30 "C++ Now edition" released]
by Niall Douglas 19 Mar '15

19 Mar '15

Dear Boost, I am very pleased to announce the v1.30 release of proposed Boost AFIO, a Boost library implementing asynchronous file input/output which has been in the review queue since 2013. This is the version of AFIO which will be overviewed in my talk at C++ Now 2015. It also demonstrates the validity of the clang AST driven BindLib standalone Boost library conversion technique which will also be overviewed at C++ Now. Source distro: https://github.com/BoostGSoC13/boost.afio/archive/v1.30_Boost_v1.57.zi p Docs and CI dashboard: https://boostgsoc13.github.io/boost.afio/ Major new features in the v1.30 release: * Performance was improved by removing the transactional memory support in the v1.2 engine which is now compile time enabled only. Throughput now reaches up to 85% of raw ASIO and average latencies were reduced by 48%, yielding a 15 microsecond average latency with +/- 0.15 microsecond at a 95% confidence interval. This should enable AFIO to handle the latest generation PCIe SSDs with their 80 microsecond latencies reasonably well. * AFIO is now capable of complete standalone usage no Boost dependencies whatsoever, including for its unit testing via a Boost.Test emulation. * Due to its use of libclang AST generated template aliasing to allow user swapping of STL 11 implementation, minimum compilers required are now VS2013, GCC 4.7 and clang 3.2. All the VS2010 workarounds baggage has been eradicated. * All things related to async_data_op_req are now fully metaprogrammed with automatic generation by the compiler of suitable ASIO scatter-gather buffers from input types and STL containers with correct scatter-gather buffer coalescing where safe to do so. This automatic generation is user customisable via free function specialisation. * Support for relative paths from an open file descriptor was added. This lets you specify a file descriptor as a base from which a path fragment operates with the path resolution atomically performed in the kernel, and therefore the path of the base file descriptor may rapidly change safely. * AFIO is now optimally filing system race condition safe on all supported platforms, with per-API documentation of how much race safety is guaranteed per platform. A soak unit test verifies per commit that perfect race safety under severe and rapid filing system change is maintained. * A new afio::path type which very thinly wraps filesystem::path was added. The new afio specific path type makes the management of NT kernel path to Win32 path transition and conversion explicit, and therefore much harder to accidentally get wrong. A new normalise_path() function can convert a NT kernel path to a traditional Win32 path, complete with drive letter. * New platforms supported: Apple OS X and Android 5.0. * New filing system features support: All platforms: sparse file support, storage extent enumeration, extent deallocation ("hole punching"), volume metadata fetching (statfs), open file handle path discovery, hard link support, atomic relink (rename) support. Windows only: file symlinking, NT lock file performance flags (lock file performance is now not far from POSIX), workaround semantics for all the ways Windows will surprise you on the filing system such as files and directories which won't delete. AFIO now does a fair job of replicating POSIX filing system semantics on Windows (and better than Mingw/Cygwin presently). Linux: symlinks are now opened as file descriptors on kernels supporting that feature. * Doubled the size of the tutorial, with all the new material being non-toy examples. There is a particularly nifty "File locking via only atomic appending and hole punching" algorithm implementation in there, and it holds up surprisingly well compared to traditional file locks except on ZFS. Plus, it's completely portable. * Some utility routines in preparation for AFIO v1.4: a cryptographically strong random filename generator, a hugepage TLB STL allocator useful for efficient file copy buffers, a very highly optimised C++ 14 constexpr constructing arbitrary Hamming code SECDED template class (an amazing 22 cycles per byte for the 32784,32768 code), and secure to-hex and from-hex validating converters. * No shortage of bug fixes, helped hugely by additional unit testing for correct error handling. Detailed changelog can be found at https://boostgsoc13.github.io/boost.afio/doc/html/afio/release_notes.h tml. I'll tag a Boost 1.58 release on github once Boost 1.58 is out. This release took far longer than I originally intended mainly due to the extensive debugging of weird filing system races, and for six weeks now I've been working till 5am every night after my day job. I cannot tell you how glad I am to see this release out! My enormous thanks to my family who have put up with a lot for this release, and to my employer for a fairly dopey employee recently. Bed, here I come! Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

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[Phoenix] Version 1.57 of Phoenix breaks when used with MSVC 2010 compiler?
by Andrew Nordquist 19 Mar '15

19 Mar '15

Hello, folks - I must be doing something wrong, but I can't figure it out. I/we have been using Boost in our 20,000+ lines of C++ code for a few years now. We started with 1.43, went smoothly to 1.53, and although it was bumpy going from MSVC 2008 to MSVC 2010, we are there now. We are now using MSVC 2010 and Boost 1.53. We use many routines, including Phoenix, Spirit, bind, tie, etc. I am attempting to migrate to Boost 1.57. Got clobbered with about 400 lines of unexpected diagnostic in the compiler. That is the attached file. In the file, the lines showing the files named "cutoffitem.cpp" and "densitydelegate.cpp" are ours, but what is between these two lines is coming from Boost. It appears that it could be a C++11 type of problem, but I'm not sure . I read about that potential problem with the [utility] [result_of] class template in the report designated n3276 and in the 1.57 [utility] documentation. I think the major concern with this issue was going to Boost 1.52. In our code, I tried a quick-fix precompiler #define, but it did not work. Got any ideas? I'm about to go back to version 1.53, at least until I upgrade to Visual Studio 2013. Thank you, /Andrew Nordquist Research Analyst Southwest Research Institute San Antonio, TX, USA

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[geometry] Compile error on project_inverse_transformer.hpp
by Jeremy Murphy 19 Mar '15

19 Mar '15

Hi Geometry team, nice to meet some of you (Adam, Barend, Menalaos) at Meeting C++ last year! I started doing projection transformations for the first time recently and found some compilation errors (using gcc or clang) when I include "project_inverse_transformer.hpp". Specifically, this is the amusingly helpful output from clang 3.6: project_inverse_transformer.hpp:63:9: error: no member named 'convert' in namespace 'boost::geometry::detail'; did you mean 'concept'? and project_inverse_transformer.hpp:63:9: error: no template named 'point_to_point' in namespace 'boost::geometry::concept'; did you mean 'detail::conversion::point_to_point'? Are these just known unfinished features? Thanks, cheers. Jeremy

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[asio] wrap lambda async_receive call
by Andrew Hundt 18 Mar '15

18 Mar '15

In C++11 is there an easy way to use boost::asio::io_service::strand::wrap() on a lambda function handling the return of an async_receive call? As noted in the docs (link below it looks like there has to be an implementation of asio_handler_invoke but I'm not sure how that would work for a lambda function. Looking through the C++11 examples I can't find any examples of using a strand. Any help would be greatly appreciated. http://www.boost.org/doc/libs/1_57_0/doc/html/boost_asio/overview/core/stra… Cheers! Andrew Hundt

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Better late than never - command line interface to on line code generator
by Brian Wood 17 Mar '15

17 Mar '15

In 2007 there was some discussion here about on line code generation: http://lists.boost.org/Archives/boost/2007/02/116997.php One thing I said back then was: "There isn't a library to download." That's changed and now there's an archive that can be downloaded: http://webEbenezer.net/build_integration.html Martin Slater, commenting on the fact that the only way to use the code generator was through a web interface, said: "the fact that it cannot be integrated into the build process easily ... would deter many from using it" I agreed with him on that point at the time and have spent a lot of time since then developing a command line interface to make it easy to integrate on line code generation into build processes. The archive mentioned above is the result of that work. So now I would like to ask for further thoughts and feedback. How can it be improved? It has support for some Boost types and I'm open to adding support for more. Tia. -- Brian Ebenezer Enterprises - In G-d we trust. http://webEbenezer.net

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Boost release 1.58.0 beta 1 is now available from SourceForge
by Marshall Clow 17 Mar '15

17 Mar '15

Boost release 1.58.0 beta 1 is now available from SourceForge See http://sourceforge.net/projects/boost/files/boost/1.58.0.beta.1/ <http://sourceforge.net/projects/boost/files/boost/1.58.0.beta.1/> This release contains three new libraries: • Endian: Types and conversion functions for correct byte ordering and more regardless of processor endianness. • Sort: includes spreadsort, a general-case hybrid radix sort that is faster than O(n*log(n)) • WinAPI: For details of what's in the release, see http://www.boost.org/users/history/version_1_58_0.html <http://www.boost.org/users/history/version_1_58_0.html>. Note that the links to files on this web page are for the final release - use the SourceForge link above to get the beta files. Please download the beta, give it a try, and report any problems you encounter. IMPORTANT NOTE: There is a bug with the build scripts; you have to specify the address-mode and architecture to b2. I used: ./b2 address-model=64 architecture=x86 (this will be fixed before the final release) Thanks, -- The Boost Release Team

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Boost::MSM: Transition Priority
by georg＠schorsch-tech.de 17 Mar '15

17 Mar '15

I try to use boost::MSM to implement a simple state machine for testing purpose. There are several events which have to be processed in the right order, so i defer the other events, which are currently not allowed. I try to defer the events in the transition table, to have one place to look for it, despite having all states to look, what events they defer. I tried to change the transition rows to change their priorities, but it didnt help. If i unkomment the anonymous transition from live_got_image to live_wait_for_image, it works as expected, but i want to transition automaticly to repeatedly enter the states live_wait_for_image/live_got_image until the ev_stop_live get sent. I expect the following output: ------------------------------ entering: fsm_master entering: not_ready no transition from state 0 on event struct `anonymous namespace'::ev_stop_live leaving: not_ready starting: live_wait_for_image leaving: live_wait_for_image starting: live_got_image leaving: live_got_image entering: not_ready but actually i get the following output: ---------------------------------------- entering: fsm_master entering: not_ready no transition from state 0 on event struct `anonymous namespace'::ev_stop_live leaving: not_ready starting: live_wait_for_image leaving: live_wait_for_image starting: live_got_image leaving: live_got_image starting: live_wait_for_image I use boost 1.57.0 and MSVC-2013 (VS-12). Could anybody get me a useful hint? Georg Here is the code: #include <iostream> // back-end #include <boost/msm/back/state_machine.hpp> //front-end #include <boost/msm/front/state_machine_def.hpp> #include <boost/msm/front/functor_row.hpp> namespace msm = boost::msm; namespace mpl = boost::mpl; namespace { using namespace boost::msm::front; // events struct ev_start_stop {}; struct ev_start_live {}; struct ev_stop_live {}; struct ev_learn {}; struct ev_load {}; struct ev_got_image { int payload; }; // front end: define the FSM structure struct fsm_master_ : public msm::front::state_machine_def<fsm_master_> { typedef int activate_deferred_events; template <class Event, class FSM> void on_entry(Event const&, FSM&) { std::cout << "entering: fsm_master" << std::endl; } template <class Event, class FSM> void on_exit(Event const&, FSM&) { std::cout << "leaving: fsm_master" << std::endl; } // the fsm states which are not sub state machines struct not_ready : public msm::front::state<> { template <class Event, class FSM> void on_entry(Event const&, FSM&) { std::cout << "entering: not_ready" << std::endl; } template <class Event, class FSM> void on_exit(Event const&, FSM&) { std::cout << "leaving: not_ready" << std::endl; } }; // The list of FSM states struct live_wait_for_image : public msm::front::state<> { template <class Event, class FSM> void on_entry(Event const&, FSM&) { std::cout << "starting: live_wait_for_image" << std::endl; } template <class Event, class FSM> void on_exit(Event const&, FSM&) { std::cout << "leaving: live_wait_for_image" << std::endl; } }; struct live_got_image : public msm::front::state<> { // here we got the image and we can check, if we need to react on an external event // otherwise transit to wait_for_image and fetch the next image template <class Event, class FSM> void on_entry(Event const&, FSM&) { std::cout << "starting: live_got_image" << std::endl; } template <class Event, class FSM> void on_exit(Event const&, FSM&) { std::cout << "leaving: live_got_image" << std::endl; } }; // --------------------------------------------------- // initial state: fsm_master_ typedef not_ready initial_state; typedef fsm_master_ l; struct transition_table : mpl::vector< // Start Event Next Action Guard // +---------------------+----------------+-------------------+-------------------+----------------+ _row < not_ready, ev_start_live, live_wait_for_image >, _row < live_wait_for_image, ev_got_image, live_got_image >, Row < live_wait_for_image, ev_stop_live, none , Defer , none >, _row < live_got_image, none, live_wait_for_image >, _row < live_got_image, ev_stop_live, not_ready > // +---------------------+----------------+-------------------+-------------------+----------------+ > {}; // Replaces the default no-transition response. template <class FSM, class Event> void no_transition(Event const& e, FSM&, int state) { std::cout << "no transition from state " << state << " on event " << typeid(e).name() << std::endl; } }; // back-end: fsm_master typedef msm::back::state_machine<fsm_master_> fsm_master; } void test() { fsm_master s; s.start(); s.process_event(ev_stop_live()); // this gets no transitioned s.process_event(ev_start_live()); // this one enters live s.process_event(ev_stop_live()); // this gets defered s.process_event(ev_got_image()); // this one enters got_image and the stop live should get processed. // now we should be in not ready again, but we are still in live_wait_for_image } int main() { test(); return 0; }

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Re: [Boost-users] [scope_exit] 1.57 MSVC C4003 warning
by Cheng Mo 17 Mar '15

17 Mar '15

Hi, Edward： Thanks a lot.

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How to get Text Archive with CRLF after each record?
by Tony Camuso 16 Mar '15

16 Mar '15

I'm just getting one big line, no CRLF in the archive. Makes it difficult to debug. Interesting thing is that I was seeing CRLF in a previous archive I created in another app. There is no difference I can detect in the way I'm archiving in this app. Tool chain ... g++ (GCC) 4.9.2 20150212 (Red Hat 4.9.2-6) libstdc++-4.9.2-6.fc21.x86_64 libstdc++-devel-4.9.2-6.fc21.x86_64 Code... typedef std::multimap<unsigned, int> cnodemap_t; typedef cnodemap_t::value_type cnpair_t; typedef cnodemap_t::iterator cniterator_t; typedef std::multimap<unsigned, qnode> qnodemap_t; typedef qnodemap_t::value_type qnpair_t; typedef qnodemap_t::iterator qniterator_t; typedef qnodemap_t::reverse_iterator qnriterator_t; struct qnode { qnode(){} enum ctlflags flags; std::string sname; std::string stypnam; std::string sdecl; cnodemap_t parents; cnodemap_t children; template<class Archive> void serialize(Archive &ar, const unsigned int version) { if (version){;} ar & flags & sdecl & sname & parents & children; } }; class Cqnodemap { public: Cqnodemap(){} qnodemap_t qnmap; template<class Archive> void serialize(Archive &ar, const unsigned int version) { if (version){;} ar & qnmap; } }; static inline void write_cqnmap(const char *filename, Cqnodemap& cqnmap) { ofstream ofs(filename, ofstream::out | ofstream::app); if (!ofs.is_open()) { cout << "Cannot open file: " << filename << endl; exit(1); } { boost::archive::text_oarchive oa(ofs); oa << cqnmap; } ofs.close(); }

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Re: [Boost-users] [scope_exit] 1.57 MSVC C4003 warning
by Cheng Mo 16 Mar '15

16 Mar '15

Hi Filip: It is happened on VS 2010 as well. Hi Edward: Excuse me about this question postponed. I have just had this problem and have found this thread. Could you tell me what mean by "BOOST PP level" does ? Thanks. Sincerely Mo.Cheng

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Boost 1_58_0_rc1 is available for testing
by Marshall Clow 16 Mar '15

16 Mar '15

Release candidate files for 1.58.0 beta 1 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. IMPORTANT NOTE: There is a bug with the build scripts; you have to specify the address-mode and architecture to b2. I used: ./b2 address-model=64 architecture=x86 to test this. The files (and associated md5s) are: MD5 (boost_1_58_0_b1_rc1.7z) = 302c7dfc917227843d24beed33ccc99c MD5 (boost_1_58_0_b1_rc1.tar.bz2) = d7d030e85bf5534a328c108c62a7fb0e MD5 (boost_1_58_0_b1_rc1.tar.gz) = ec90cd23bdc99c5eaf88245ea94a28e0 MD5 (boost_1_58_0_b1_rc1.zip) = dc8379fb95c84fe2fca53a4b2c96da23 Thanks! -- The release managers

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[Asio] Need help making a custom service
by Kyle Edwards 16 Mar '15

16 Mar '15

Hello everyone, First off, I would like to say that I have been using Boost for the past few years, and have found it very useful. Thanks for all your hard work! Second, I have a question about making a custom service. I would like to make a service that triggers a callback when a GPIO pin changes state and triggers an interrupt (I'm using a Raspberry Pi.) I have (or can obtain) a file descriptor that can be poll()'d, select()'d, or epoll'd and which omits high-priority events (POLLPRI, EPOLLPRI, etc.). This entire use case is pretty Linux-specific, so it doesn't have to be very portable. What I would like to be able to do is something like this: // CODE STARTS HERE #include <iostream> #include <boost/asio.hpp> class gpio_interrupt { public: gpio_interrupt(boost::asio::io_service &io_service, unsigned int number) { // Asio magic goes here } template <typename Callback> void async_wait(Callback c) { // Asio magic goes here } }; static void my_callback(const boost::system::error_code &ec) { if (ec) return; std::cout << "Pin changed state" << std::endl; } int main(int argc, char **argv) { boost::asio::io_service io_service; gpio_interrupt interrupt(io_service, 21); interrupt.async_wait(my_callback); io_service.run(); return 0; } // CODE ENDS HERE I've looked a little bit at the Boost.Asio code (in particular the socket code) to get an idea of how I would do this, but there are so many different classes and inner classes that I'm not sure where to get started. Can someone help me? Thanks in advance! -- Kyle Edwards Software Developer 20 Corporate Circle | Albany, NY 12203 office 888-4BULLEX | 518.689.2023 | fax 518.689.2034 | web: www.bullex.com

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[context] Crash in case of exception from a context
by Tamas.Ruszkai＠leica-geosystems.com 16 Mar '15

16 Mar '15

I use boost::context to implement cooperative multitasking. At the moment I use boost 1.57 on Windows 7 with VisualStudio 2013. Everything works fine until I throw an exception from a context created by "boost::context::make_fcontext(.......)". I have seen someone had the same problem and it was caused by the Windows OS, that checks the exception hierarchy in the stack and if it finds that the starting point is not the one that should come from the OS then it terminates the process. It suspects some malitious code that corrupted the stack. http://www.blinnov.com/en/2013/04/11/english-boostcontext-and-seh/ This guy metioned in his blogpost, that this problem was solved in boost 1.53 ("Boost 1.53 has updated and fixed version of boost::context library that addresses exactly this problem. "), but somehow I still have the same thing in 1.57. Is there some special preprocessor flag (#define) that I have to activate to get this fix? Thanks! Tamas

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Boost forces Cygwin build to be 32-bit, even when it shouldn't
by Chris Taylor 15 Mar '15

15 Mar '15

I'm having trouble building boost under Cygwin. I've installed the 64 bit version of Cygwin and all programs are compiled as 64 bit. Yet, for some reason, the header ./boost/python/detail/wrap_python.hpp defines SIZEOF_LONG to be 4 when __CYGWIN__ is defined, which is only valid for a 32-bit system. This signals an error check in a python header, and the build fails. Why does this #define exist? Can we get rid of it? More info here: http://stackoverflow.com/questions/29004590/compiling-boost-on-cygwin-heade…

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[regex] stuck with expression syntax / exception
by Thomas 15 Mar '15

15 Mar '15

Hi, I am pretty much a complete novice to the boost::regex library, and stuck with the following snippet: std::string String = " (of 1000 elements; 67.10%)"; try { std::cout << boost::regex_match(String, boost::regex("^ (of \\d+ elements; .+%)$")) << std::endl; std::cout << boost::regex_match(String, boost::regex(" (of \\d+ elements;.+")) << std::endl; } catch(boost::regex_error const &) { std::cout << "caught boost::regex_error!"; } Two questions: First, why does the first not match? Second, why does the second throw? The idea of the regex is that the first number is an integer, and for the percentage number the formatting is unspecified but must terminate with '%'; otherwise all characters must match exactly. thanks, Thomas

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[Range] concatenate 2 vectors
by Christophe B. 14 Mar '15

14 Mar '15

Hi all, I want to construct a static const vector being the result of concatenation of two other vectors. I was thinking to use boost::push_back, but it takes a container as a lvalue reference as a 1st argument. I could develop the following piece of code template <typename Container, typename Range> Container concat(Container const &c, Range cont& r) { Container result = c; return boost::push_back(result, r); } static const std::vector<std::string> v = concat(v1, v2); But I wanted to avoid to reinvent the wheel. Currently, I am living with this kind of writing: static const auto v = [&]{ std::vector<std::string> result = v1; return boost::push_back(result, v2); }(); Does boost libraries offer a better alternative to this construct ? Christophe

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Need site-config.jam msvc example for cxxflags
by David Highley 13 Mar '15

13 Mar '15

> We are beating our head on the wall trying to get site-config.jam to add > an include path for the Windows SKD includes. We have tried many flavors > of this: > > using msvc : 12.0 : : <cxxflags>"-IC:\\Program Files (x86)\\Microsoft > SDLs\\Windows\\v7.1A\\Include" ; We found the magic and the file now looks like this. using msvc : 12.0 : : <compileflags>"-I\"C:\\Program Files (x86)\\Microsoft SDKs\\Windows\\v7.1A\\Include\"" ; > > > We need it to only be used with the 12.0 or Studio 2013 version of > Studio. >

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Need site-config.jam msvc example for cxxflags
by David Highley 13 Mar '15

13 Mar '15

We are beating our head on the wall trying to get site-config.jam to add an include path for the Windows SKD includes. We have tried many flavors of this: using msvc : 12.0 : : <cxxflags>"-IC:\\Program Files (x86)\\Microsoft SDLs\\Windows\\v7.1A\\Include" ; We need it to only be used with the 12.0 or Studio 2013 version of Studio.

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Re: [Boost-users] Boost 1_58_0_rc1 is available for testing - coroutine2 missing
by Oliver Kowalke 12 Mar '15

12 Mar '15

boost.coroutine2 is missing in the archive

2 6