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Boost iostreams for binary data
by Robert Dailey 03 Feb '17

03 Feb '17

I have my own BinaryInputStream and BinaryOutputStream classes that simply take a reference to some container that meets the requirements of random access and contiguous internal memory. It doesn't own this container, but rather serves as an adapter to the container to allow stream operators to be used for streaming out data. For example, you can stream a `std::uint32_t` to the binary stream, and it will insert 4 elements into an internal byte vector which is just `std::vector<std::uint8_t>`. I did not implement these in terms of IO streams, because those seemed a bit overkill and make a lot of assumptions on the data being text-only. Also I can't stream binary data into vectors, lists, and other containers because the data simply can't be parsed. Each stream out of a binary vector must be done so with a finite count of bytes. Would it make sense to implement these objects in terms of the IOstream facilities provided by boost? I know these were designed to make defining stream classes easier, but honestly I don't have a lot of experience with them. Any feedback on this? Thanks in advance. I can provide some example code if needed.

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Mail List Migration - Update
by Michael Caisse 02 Feb '17

02 Feb '17

The Boost mail lists are now migrated to a new set of servers. This change affected all mail lists and web resources (signing up, changing passwords, moderator access, archives...) that were associated with the domain lists.boost.org . If you are having difficulties, please drop me an email. (Oh the irony) Happy coding! michael -- Michael Caisse Ciere Consulting ciere.com

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Mail Lists Migrate at 00:00 UTC Feb 3
by Michael Caisse 02 Feb '17

02 Feb '17

The following mail lists will be switched to new infrastructure at 00:00 UTC on February 3rd. There will be a small interruption while the DNS/MX records propagate. * Boost - Boost developers' mailing list * Boost-announce - Boost announce-only mailing list * Boost-bugs - Bugs reported/updated through Boost's Trac * Boost-build - Boost.Build developer's and user's list * Boost-cmake - Discussion of the CMake-based build system for Boost * Boost-commit - Boost Subversion commit messages * Boost-docs - Discussion of Boost Documentation * Boost-Interest - Moderated announcements of interest to the Boost community. * Boost-maint - Boost community maintenance mailing list * Boost-mpi - Discussion of Boost.MPI development * Boost-test - Test list for the boost mailing lists * Boost-Testing - Running Boost regression tests * Boost-users - Boost Users mailing list * Geometry - Boost.Geometry library mailing list * glas - Generic Linear Algebra Software * proto - Discussions about Boost.Proto and DSEL design * threads-devel - Discussions about the boost.thread library * ublas - ublas mailing list -- Michael Caisse Ciere Consulting ciere.com

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Cross compiling context library of boost for windows 32 on a linux 64-bit machine
by Jack Kumba 01 Feb '17

01 Feb '17

Hello, Did someone succeed cross compiling context library of boost for windows 32 on a linux 64-bit machine? OR Is it even possible? I see the following error: libs/context/src/unsupported.cpp:7:2: error: #error "platform not supported" #error "platform not supported" Also, there is this ticket on this issue https://svn.boost.org/trac/boost/ticket/7262 Please advise me. Thanks, Jack

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Cross compiling boost (context, coroutine, filesystem, and system libraries) on ubuntu 64-bit for windows 32-bit (running on intel atom e3845 that is x86-64 bit)
by Jack Kumba 31 Jan '17

31 Jan '17

Hello, I want to cross compile context, coroutine, filesystem, and system libraries of boost for windows 32-bit (running on Intel Atom E3845) on my ubuntu 64-bit. To do that, I create a user-config.jam file in my homedirecotry and put the following: using gcc : mingw : i686-w64-mingw32-g++ : <compileflags>-m32 <linkflags>-m32 ; then, I would like to run following command: b2 --with-context --with-coroutine --with-system --with-filesystem --prefix=/home/jagdish/COMMELEC/prerequisits/real_boost_installation_dir/ toolset=gcc-mingw target-os=windows variant=release link=static address-model=32 runtime-link=static threading=multi architecture=x86 instruction-set=x86 abi=ms install is it good? Specifically, the options architecture, instruction-set, address-model? thanks in advance for your help. best, jack

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[thread] understanding multiple statically-linked boost::thread in same process
by Simon Haegler 31 Jan '17

31 Jan '17

hi boost users, i am debugging an application where several shared libraries contain statically-linked copies of boost::thread (and other boost components). this means the static part of boost::thread is multiple times present in the process. on macos (apple clang 7.3) we see rare (but reproducible) access violations caused by boost::thread_specific_ptr::get() unexpectedly returning nullptr. if we enable assertions we get an assert in thread.cpp:151 if we dynamically link boost the problems go away. i can superficially understand that linking only one "common" instance of boost::thread is "more safe". what could be the explanation for this observation? is this setup even supported? one theory is that the implementations in pthread/thread_heap_alloc.hpp interfere with each other... the specific line where we get an unexpected nullptr (actually a bad reference) is here: https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_CGAL_cgal_b… the definition of CGAL_STATIC_THREAD_LOCAL_VARIABLE is here?: https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_CGAL_cgal_b… boost version is 1.59 TIA, simon -- Simon Haegler | Software Engineer Esri R&D Center Zurich | Foerrlibuckstrasse 110 | 8005 Zurich | Switzerland T +41 44 204 60 80 | shaegler(a)esri.com

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C++Now 2017 Registration is Open
by Jon Kalb 31 Jan '17

31 Jan '17

Boost Users, Registration for C++Now 2017 is now open: http://bit.ly/CppNow2017IsOpen The conference will be in Aspen, Colorado from May 15th to 20th. The deadline for submissions is this Friday: http://cppnow.org/2017-conference/announcements/2017/01/06/call-for-submiss… Jon

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Re: [Boost-users] [boost::asio] Wait for multiple async_read()'s
by Marat Abrarov 30 Jan '17

30 Jan '17

Hi Adam, > I'd like to write data to these streams then wait for everyone to reply before performing computation on the resulting data. What about Chris's coinvoke (http://blog.think-async.com/2008/10/asynchronous-forkjoin-using-asio.html)? Could it help for you case? Regards, Marat Abrarov.

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[preprocessor]how to compute include with .hpp in name?
by Larry Evans 28 Jan '17

28 Jan '17

With the attached, I get the error: g++ computed_include.hpp.cpp -o a.out In file included from computed_include.hpp.cpp:4:0: computed_include.hpp.cpp:5:22: error: pasting "computed_include" and "." does not give a valid preprocessing token #define FILENAME_INC computed_include ^ computed_include.hpp.cpp:7:58: note: in expansion of macro ‘FILENAME_INC’ #define FILENAME_CAT_STR BOOST_PP_STRINGIZE(BOOST_PP_CAT(FILENAME_INC,HPP_EXT)) ^ computed_include.hpp.cpp:8:10: note: in expansion of macro ‘FILENAME_CAT_STR’ #include FILENAME_CAT_STR ^ Is there some other way this can be done? TIA. -regards, Larry

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[boost::asio] Wait for multiple async_read()'s
by Adam Zegelin 28 Jan '17

28 Jan '17

Hi, I'm writing a boost::asio application that communicates with multiple streams. I'd like to write data to these streams then wait for everyone to reply before performing computation on the resulting data. What is the best way to implement this? The route I've ventured down involves me calling async_write() on each stream, with the callback hander executing async_read(). But this where I'm stuck. What is the best way to execute one final hander once all read operations have completed? One solution I've found, though it feels "un-asio" is to pass the use_future option as the hander for the reads. The result is futures for each read, which I can then place into a list<future>, and have an additional io_service.post()'ed handler call get() on these futures. The only issue with this is that I must call io_service.run() from more than one thread, since the handler calling get() blocks — otherwise I can potentially deadlock the whole application. Another alternative I can think of is that the function that schedules all the async_writes knows ahead-of-time the number of reads that need to be completed. Each async_read() handler would put its results into a shared list and then, if the list's size is equal to the expected number of results, fires the "completion" handler. While easy enough to implement, this seems fraught with issues. If there is more than one thread calling io_service.run(), then access to the shared list has to be synchronised. Also, it doesn't seem very generic — I have a number of places where this write n, read n, execute (or is it map, reduce?) pattern needs to happen, and I'd prefer a solution that was write one, worked everywhere. Any help would be appreciated. - Adam

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