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[uuid] constexpr uuid from string and ""_uuid literal
by Tobias Loew 23 Dec '18

23 Dec '18

Hi, while searching for constexpr GUID from string generators, I found https://gist.github.com/AlexBAV/b58e92d7632bae5d6f5947be455f796f . Since I still work with VS 2015, I wrote a C++11 constexpr version incl. boost-uuid generators. If there's interest adding this to boost uuid, please have a look at https://github.com/tobias-loew/constexpr-GUID-cpp-11 Tobias -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Users-f2553780.html

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Patch for using boost-1_69_0 and clang-cl
by JR Cary 23 Dec '18

23 Dec '18

I found that I had to apply the attached patch to build another project that uses boost with clang-cl, or else I got an error that complained about the non-existence of std::snprintf. John Cary

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Error when trying to build Boost 1.69.0 with LLVM
by Osman Zakir 22 Dec '18

22 Dec '18

When trying to build Boost 1.69.0 with LLVM, I had an error about the "register" keyword, regarding the removal of it in C++17. I searched on the Web and found out that I can use the "-Wno-register" flag to calm down Clang 6.0.0. What do I do in Clang 8.0.0? The same?

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boost_1_19_0 fails to build random using clang-cl
by JR Cary 21 Dec '18

21 Dec '18

This is now more of an FYI, as I can disable random and get the build I need. boost 1_69_0 clang version 8.0.0 (trunk 349323) Windows 10 Build command: ./b2 toolset=clang-win runtime-link=shared link=shared define=BOOST_TEST_DYN_LINK cxxflags='-DBOOST_THREAD_DONT_USE_CHRONO' linkflags='-DBOOST_THREAD_DONT_USE_CHRONO' address-model=64 threading=multi variant=release -s NO_COMPRESSION=1 --layout=system --abbreviate-paths -j2 --without-python --without-mpi --without-log --without-math stage The first error is Creating library bin.v2\libs\random\build\clng-win-8.0.0\rls\adrs-mdl-64\thrd-mlt\boost_random.lib and object bin.v2\libs\random\build\clng-win-8.0.0\rls\adrs-mdl-64\thrd-mlt\boost_random.exp^M random_device.obj : error LNK2019: unresolved external symbol __imp_CryptEnumProvidersA referenced in function "public: __cdecl boost::random::random_device::impl::impl(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0impl@random_device@random@boost@@QEAA@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)^M random_device.obj : error LNK2019: unresolved external symbol __imp_CryptAcquireContextA referenced in function "public: __cdecl boost::random::random_device::impl::impl(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0impl@random_device@random@boost@@QEAA@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)^M random_device.obj : error LNK2019: unresolved external symbol __imp_CryptReleaseContext referenced in function "public: __cdecl boost::random::random_device::impl::~impl(void)" (??1impl@random_device@random@boost@@QEAA@XZ)^M random_device.obj : error LNK2019: unresolved external symbol __imp_CryptGenRandom referenced in function "public: unsigned int __cdecl boost::random::random_device::operator()(void)" (??Rrandom_device@random@boost@@QEAAIXZ)^M bin.v2\libs\random\build\clng-win-8.0.0\rls\adrs-mdl-64\thrd-mlt\boost_random.dll : fatal error LNK1120: 4 unresolved externals^M clang-cl: error: linker command failed with exit code 1120 (use -v to see invocation)^M The build succeeds upon adding --without-random to the build invocation. I tried attaching the full log, but then the message was rejected for being too large. ..................John Cary

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Questions about Boost.Multiprecision..
by A Z 20 Dec '18

20 Dec '18

I want to be performing some algebraic functions work on cpp_rational which I will be using templates with the following type to configure precision (and scale?) #include <boost/multiprecision/cpp_int.hpp> in order to avoid the use of floating point types. --What is the #include statement for cpp_rational? I can't manage to find it. -When using non-floating point, is there a method to obtain a variable precision pi, or do I have to use arccos(-1); ? What is the file to import for that? -If I want to import a non-floating-point (cpp_rational) library power, nth root, trigonometry, all the useful function, what is the #include and the file in boost for that?

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Having some trouble with bootstrapping Boost to use LLVM
by Osman Zakir 20 Dec '18

20 Dec '18

I changed the project-config.jam file in my Boost source tree to have Boost.Build use LLVM, but then when I used "bootstrap" command after, I saw that it was still using MSVC. When I looked at the project-config.jam file again at that point, I saw that its content had been reverted back to the default one for building with MSVC. What's going on? What do I need to do? Is there an argument I need to provide to the bootstrap command here so that it'll keep the configuration file content that I want it to? And is there no help command that would let me see what arguments, if any, I can pass to the tool? Another thing I want to ask is whether or not I need to have Boost.Built emit library files with a .bc extension to be able to link them with code I want to build using the Emscripten compiler. I ask because Emscripten needs compiled libraries to have been compiled to LLVM bitcode, and when Emscripten itself does this it adds the .bc extension instead of the .lib one.

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integer_log2.hpp header deprecation using Boost
by Michael Powell 19 Dec '18

19 Dec '18

Hello, I am receiving a deprecation warning: d:\dev\boost.org\boost_1_69_0\boost\pending\integer_log2.hpp(7): note: This header is deprecated. Use <boost/integer/integer_log2.hpp> instead. The immediate includes are these: #include <boost/uuid/uuid.hpp> #include <boost/uuid/uuid_io.hpp> #include <boost/uuid/random_generator.hpp> But I am also leveraging Spirit, Format, Variant, Optional, to name a few, that I can determine. I am not including "integer_log2.hpp" directly, so I wondered which library(ies) might have this as a dependency? Spirit? Phoenix, via Spirit? Format? Thoughts? Suggestions? Cheers, Michael Powell

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odeint: how to solve ODE as you go without deciding upfront what the interval is?
by Yuri 19 Dec '18

19 Dec '18

The function 'integrate' solves ODE for a pre-defined interval of time. What if I don't know what the interval is? I just need a few values, and then I would like to decide if I need more values, and when to stop. I don't want to just solve for some arbitrarily large interval, because this would waste CPU. On the other hand, choosing the shorter original interval and then continuing would introduce unnecessary errors if one would do this too many times. It seems like either the 'observer' function should have another argument: 'stop', or the interface should allow continuation. Yuri

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[Spirit] X3 thread-safety
by Igor R 19 Dec '18

19 Dec '18

Hello, In my project I run x3-based parsers in parallel, using openmp. I've just moved from boost 1.64 to 1.68, and the parsers now cause segfault (heap corruption) - quite consistently, every time I run the program. OTOH, with 1.64 it never crashed. Before I begin to debug it in depth, I'd like to know if there's some known issue with Spirit's thread-safety in Boost 1.68. Did anyone encounter thread-safety issie with the recent Spirit versions? Thanks.

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Build boost asio http server examples single threaded using c++03
by Eric Curtin 19 Dec '18

19 Dec '18

Hi Guys, I was wondering if anyone could help me out building all the boost asio http server examples from: https://github.com/boostorg/asio/tree/develop/example/cpp03/http But catch is, I need to use c++03/98, single threaded without dependencies on std::thread, boost::thread or posix threads. I also need static linking to all the other boost libraries. Also want to compile with g++ -O3 -flto on x86_64 Linux. How can I build these examples like this? This is also a question on stackoverflow: https://stackoverflow.com/questions/53822438/building-boost-asio-without-th… Lets say the build environment is this one: curtine/dockerfiles-fat:ubuntu18.04 Regards, Eric

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[Asio] Combining use_future with strands
by Sorin Fetche 19 Dec '18

19 Dec '18

Hi, Is there a way to combine the special use_future completion token with a strand? Something with the meaning of: - the asynchronous operation should pass the result to the future it returns, and - the internal operations of it (if any) should run in a strand Code snippet: asio::io_context io_context; asio::io_context::strand strand(io_context); std::future<void> f = async_my_operation(io_context, <params>, asio::use_future); //________________________________________How to add the strand here ^^^ ? The code area where I would like to apply this is in this test program: https://github.com/sorf/cpp-dev-new/blob/abf9d831a0b82fb81751eee6cfa498d3b9… The self contained program and its output is here: https://wandbox.org/permlink/pF5Hbm6jqPOmEKbO As a background, the test program I wrote is based on these Boost.Asio examples: - for strand usage (i.e. bind_executor): https://github.com/boostorg/asio/blob/develop/example/cpp03/tutorial/timer5… - for composed operations: https://github.com/boostorg/asio/blob/develop/example/cpp11/operations/comp… and implements a composed operation that runs multiple internal operations in parallel and in series. Similar to the constructor of a socket or a timer object, the operation receives as a parameter an io_context; it doesn't offer an overload that receives a strand object directly. The operation is then tested with callback completion, callback completion in a strand, future and future + strand (where the test fails). Thank you, Sorin

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How to implement a visitor pattern over an AST
by Michael Powell 19 Dec '18

19 Dec '18

Hello, I have an AST successfully building, generating text file, and subsequently Spirit Qi parsing for verification purposes. Now I want to implement a visitor pattern over that AST, somehow... For "calculators" and such, "evaluating" those expressions is one thing; however, this AST is not that. It is closer akin to a parsed Xml or Json model/tree. In other words, I'd like for it to feel sort of like an iterator if that's even possible. It should have contextual awareness where it is at all times, etc, perhaps "incrementing" is a depth first analysis. In particular I have in mind to iterate the expected and actual AST results in order to perform the verification. In other words, I might do something like this: auto expected_it = ast_visitor{&expected}; auto actual_it = ast_visitor{&actual}; REQUIRE(expected_it); REQUIRE(actual_it); REQUIRE(*expected_it == *actual_it); // Rinse and repeat ++expected_it; ++actual_it; REQUIRE(*expected_it == *actual_it); I wonder if something like this is even possible from the Boost libraries? Or interested to hear any insights on the subject. For that matter, I wonder it is more appropriate to simply implement the logical operators. Thanks! Michael Powell

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Understanding fibers
by Stephan Menzel 18 Dec '18

18 Dec '18

Hello @ll, I am in the process of transforming a sync server application to an async approach. The framework in use (not asio) instantiates and calls an object representing the call when a request comes in, allows me to do things, fill a response object and then expects me to call a finish() method which will send the response and start the next request. This is not what this question is about but more like my circumstances. All code is pseudocode please... void rpc_work() { const value = do_stuff(request); response.fill_value(value) parent->finish(); } Now some of the calls will imply calling methods, which block on some operations, waiting for external resources to respond. Obviously in an async server with only one thread, this will block everything. So I'm looking for a clever way to structure this. My approach so far (in the prototype) is to go boost::async() for those operations. Like this: void rpc_work() { // prepare work boost::async(launch::any, [request, response, parent]() { const value = do_blocking_stuff(request); response.fill_value(value) parent->finish(); }); } The way I understand boost::async or indeed std::async is, that normally it will just spawn a thread for the operation. The best I can hope for is a thread pool but this is not guaranteed either (on Linux x64 gcc 7.3). So I started looking into fibers but I'm having a hard time understanding them, which is why I post here. From what I gather, what I have here is a prime use case as it matches many things the docs talk about. And yet they also suggest that the fibers are very intrusive and everything underneath do_blocking_stuff() would have to be aware of being in a fiber and yield() when appropriate. Is this correct? What would this mean? Most if not all of the blocking operations are using boost::thread::futures in their blocking things. They would do things like... value_t do_blocking_stuff(request) { boost::future<value_t> fv = retrieve_value_from_somewhere(); fv.wait_for(timeout); return fv.get() } Now, considering I would use fibers in the server, would I have to use 'fiber futures' here to make this work? To make the blocking functions automatically 'fiber aware' and yield() when they would block? This would imply replacing the thread::futures? And if so, how will I know when the value is there and they are ready to continue? And how will I cause this continuation? Do I have to keep track of them and somehow poll() them in a loop or something? I am aware of the broad nature of my question but perhaps someone can chime in and give some hints that allow me to understand them better. They look like they would fit my use case perfectly but I am a bit reluctant of dragging the concept all throughout the code until I realize it won't work. Perhaps someone can eli5 this to me ;-) Cheers, Stephan

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Boost Process fails on Solaris 10 in async mode
by Sanket Sharma 18 Dec '18

18 Dec '18

Hi, I tried installing boost process on my Solaris 10 Sparc machine. On compiling it using gcc-6.3.0, I ran into a static assert failure at compile time at https://github.com/boostorg/process/blob/boost-1.68.0/include/boost/process…. In order to fix that, I changed static_assert(!WIFEXITED(still_active) && !WIFSIGNALED(still_active), "Internal Error"); to static_assert(!WIFEXITED(still_active), "Internal Error"); There is some discussion about this at https://www.openwall.com/lists/musl/2018/08/10/1 Now, the following code works well onCentOS 7(where no change was made to Boost process), but fails on Solaris 10 (where I made the above change as a workaround). On Solaris 10, the return code is 127 and stdout and stderr are empty. #include <iostream>#include <thread>#include <boost/process.hpp>#include <boost/asio.hpp> namespace bp = boost::process ;int main(int argc, char** argv){ std::future<std::string> dataOut; std::future<std::string> dataErr; std::string command = "ls"; boost::asio::io_service ios; bp::child c(command, bp::std_out > dataOut, bp::std_err > dataErr, ios); ios.run(); c.wait(); int result = c.exit_code(); std::string stdOut = dataOut.get(); std::string stdErr = dataErr.get(); std::cout << "Exit Code " << result << std::endl; std::cout << "stdOut " << stdOut << std::endl; std::cout << "stdErr " << stdErr << std::endl; return 0;} Output on CentOS 7 Exit Code 0 stdOut a.out main.cppProcess.cppProcess.h simple.cpp stdErr Output on Solaris 10 Exit Code 127 stdOut stdErr 1. Has my workaround to install Boost process on Solaris 10 broken it? 2. Is Boost-1.68.0 not supported on Solaris? 3. Is there a way I can get Boost Process to work on Solaris 10 in async mode? https://stackoverflow.com/questions/53780273/boost-process-fails-on-solaris… -- Regards, Sanket

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Boost version 1.69.0 already included in list of known versions in FindBoost.cmake module
by Osman Zakir 17 Dec '18

17 Dec '18

I looked in the FindBoost.cmake module and saw that version 1.69.0 is already listed as a known version. But when I configured CMake to build Jinja2Cpp after building Boost 1.69.0, I couldn't get it to find some modules of Boost. There were warning messages about imported targets and dependences or some such. Jinja2Cpp uses an earlier version of Boost from its own submodule in this case (it has a GitHub repository that I cloned from and built), but I'd like it if it used the latest version of Boost instead of an earlier version. My Boost installation is in C:/boost_1_69_0/, by the way. Could this be causing problems, or will it still be fine I configure CMake correctly? What CMake option should I use to find Boost? -DBOOST_ROOT?

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[Spirit] Comment skipper or first class member of grammar
by Michael Powell 17 Dec '18

17 Dec '18

Hello, I am turning a corner in my Protocol Buffers grammar, and it is now time for me to consider how best to approach parsing comments. Chiefly, I am weighing two options, I think: 1) A white-space, comments skipper; if memory serves there has been discussion about such a thing on either here, Boost mailing list, or other forums. 2) Or, as with some compiler environments, I'm thinking .NET Roslyn/C#, in particular, where "comment" elements are first class members of the grammar/tokens, quite literally, I think. I'm not quite sure how that would be expressed in terms of synthesized AST, when you could literally have a comment appearing virtually anywhere between tokens, especially of the C variety, i.e. /* this is a comment which may appear virtually anywhere between tokens, potentially */. Or the single line C++ variety, for example, // this is a comment through the rest of this line. // Yet, there could be multiple lines of these... optional myVar = true; // And can appear at the end of a line Thoughts? Suggestions? My first approach I think would be for (1) the skipper; however, for what I am wanting to accomplish, I can see there potentially being some value in capturing the comments and carrying them forward with the target language adapter. Best regards, Michael Powell

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[process] distinguish normal exit from termination by signal - complete
by Oliver Kowalke 17 Dec '18

17 Dec '18

Hello, I'm evaluating boost.process. It seams to me that it is impossible to distinguish a normal exit from a termination by a signal (for instance SIGBUS etc.). child::exit_code() calls eval_exit_status() that expands on POSIX to: if (WIFEXITED(code)) { return WEXITSTATUS(code); } else if (WIFSIGNALED(code)) { return WTERMSIG(code); } else { return code; } With the code above it is impossible if the returned exit_code is a `exit-code` or the number of a signal. Or do I miss something? regards, Oliver

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[process]distinguish normal exit from signaled not possible?
by Oliver Kowalke 17 Dec '18

17 Dec '18

Hello, I'm evaluating boost.process. It seams to me that it is impossible to distinguish a normal exit from a termination by a signal (for instance SIGBUS etc.). child::exit_code() calls eval_exit_status() that expands on POSIX to: if (WIFEXITED(code)) { return WEXITSTATUS(code); } else if (WIFSIGNALED(code)) { return WTERMSIG(code); } else { return code; }

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[contextual async] generator support added
by Christophe Bailly 16 Dec '18

16 Dec '18

Hello, I am still waiting for some feedbacks. I really think it makes possible to add asynchronous code very easiy, I have added the support of generators which can run with asynchronous.code. You will find the added article in the blog: https://pythonc.home.blog/ The project has been updated and the examples are available if you want to test. Regards, Chris

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[corountine2/context] forced_unwind exception on Windows with TDM-GCC
by Hao Jiang 15 Dec '18

15 Dec '18

Hello all, I am porting my program from Linux to Windows with boost coroutine2. I found 32bit program throwing boost::context::detail::forced_unwind every time when coroutine destructed. But 64bit program works like charm. terminate called after throwing an instance of 'boost::context::detail::forced_unwind' The program works well on Linux(Ubuntu). Then I tried the official example: typedef boost::coroutines2::coroutine<int> coro_t; coro_t::pull_type source( [&](coro_t::push_type& sink){ int first=1,second=1; sink(first); sink(second); for(int i=0;i<8;++i){ int third=first+second; first=second; second=third; sink(third); } }); for(auto i:source) std::cout << i << " "; Same thing happened. Platform: windows 7 64 bit Boost: 1.67/1.69 Compiler: TDM-GCC 5.1 64bit. Best,

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project-config.jam File for building Boost with LLVM toolchain?
by Osman Zakir 15 Dec '18

15 Dec '18

Sorry, but I need to see the project-config.jam file I need to use for building Boost with the LLVM toolchain again. I'm going to build it with the MSVC toolchain first and then again with the LLVM toolchain as well so that I have both the MSVC- and Clang-generated binaries. I downloaded Boost version 1.69.0 and I want to build it now. Thanks in advance.

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[boost] mixing async + sync code easily via boost::context
by Christophe Bailly 15 Dec '18

15 Dec '18

Hello, I have worked on a prototype to avoid the current limitations with async code, the use of sync + async code is really difficult, it does not co-exist easily. If you introduce async code, you have to migrate all your code ... There are alternative solutions (threads..) but here is a suggestion to overcome these limitations. It is currently a very simple prototype but I would be interested to have your feedback. I think this kind of solution can be really powerfull, but I will wait to know what you think about it. Here are the links: https://pythonc.home.blog/ https://github.com/chbailly/5a5 Regards, Chris

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C++Now (BoostCon) 2019 Call for Submissions
by Jon Kalb 14 Dec '18

14 Dec '18

The C++Now (formerly BoostCon) 2019 Call for Submissions is now open. http://cppnow.org/announcements/2018/12/2019-call-for-submissions/ C++Now will be held in Aspen, Colorado on May 5th - 10th. Colorado has become trendy for C++ conferences, but BoostCon was here first. If you are interested in Boost Libraries and have never attended C++Now, you owe it to yourself to have the BoostCon experience. The best way to get your company to send you is to have an accepted submission. The deadline is early in the new year, so don’t delay. Jon Kalb Conference Chair C++Now

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[release] Boost 1.69.0
by Marshall Clow 13 Dec '18

13 Dec '18

Release 1.69.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains numerous enhancements and bug fixes for existing libraries. For details, including download links, see < http://www.boost.org/users/news/version_1.69.0> You can also download directly from: < https://dl.bintray.com/boostorg/release/1.69.0/> SHA-256 sums: af05616f71006f97833e130aad886c96136457511ace4b5496d6566e69cbe0ca boost_1_69_0.7z 8f32d4617390d1c2d16f26a27ab60d97807b35440d45891fa340fc2648b04406 boost_1_69_0.tar.bz2 9a2c2819310839ea373f42d69e733c339b4e9a19deab6bfec448281554aa4dbb boost_1_69_0.tar.gz d074bcbcc0501c4917b965fc890e303ee70d8b01ff5712bae4a6c54f2b6b4e52 boost_1_69_0.zip To install this release on your system, see < http://www.boost.org/doc/libs/release/more/getting_started/index.html> Thanks to everyone who participated in this release. Thanks, -- The Boost Release Team Vladimir Prus, Marshall Clow, Daniel James, Micheal Caisse

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The Master branch is still closed; it will be opened tomorrow
by Marshall Clow 12 Dec '18

12 Dec '18

Thanks for your patience -- The boost release managers

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Formatting Boost.Uuid as string
by Michael Powell 11 Dec '18

11 Dec '18

Hello, I see that you can do "basic" formatting of boost::uuids::uuid via boost::format. This is good for basic formatting, but are there other format specifiers one can furnish? I'm thinking along the lines of formats such as with or without hyphens, etc. Or an ability to extend such a feature for that matter. See my C# WPF GuidGen for some examples: http://github.com/mwpowellhtx/guidgenwpf/tree/master/src/GuidGen.Wpf/Formats This is based on the Microsoft GuidGen, but using WPF technology, and with some additional formats. Thanks! Best regards, Michael Powell

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[release] 1.69.0 closed for release
by Marshall Clow 11 Dec '18

11 Dec '18

The master branch is now closed for all changes except by permission. The commit-bot isn't running on master, so the super project will need to be manually updated for any changes. If all goes well, the release candidate should be out later today. Thanks, -- The Boost Release Team

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travis runners version
by Alain Miniussi 10 Dec '18

10 Dec '18

Hi, I see that travis runners uses open MPI 1.6.5 mpirun.openmpi --version mpirun.openmpi (OpenRTE) 1.6.5 which is considered "retired" on the OpenMPI download page (https://www.open-mpi.org/) current version is 4.0.0 and most linux ditrib I see uses 2.x.x or hirgher. What is the travis runners distrib/version ? Thanks -- ----- Alain Miniussi DSI, Pôles Calcul et Genie Log. Tél. : +33492003009 (Mont-Gros) Tél. : +33483618544 (Sophia Antipolis)

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Boost.Filesystem perms on Windows
by Lars 10 Dec '18

10 Dec '18

Hello, The documentation<https://www.boost.org/doc/libs/1_68_0/libs/filesystem/doc/reference.html#En…> (boost version 1.68) for boost::filesystem::perms enumerator says; "Windows: All permissions except write are currently ignored. There is only a single write permission; setting write permission for owner, group, or others sets write permission for all, and removing write permission for owner, group, or others removes write permission for all." Does "All permissions except write are currently ignored" restriction apply to both getting permission from a file and setting permission to a file? In other words, does it apply to both boost::filesystem::status(..) and boost::filesystem::permissions(..) methods? Why does the fileysystem have this restriction? Is this some limitation in the design or a bug or missing feature? Kind regards, Lars

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Mocking with boost.test
by Sean Farrow 09 Dec '18

09 Dec '18

Hi all, I was just wondering whether boost.test provides any mocking facilities? If it doesn't is there a recommended mocking framework? Any help appreciated. Kind regards Sean.

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GIL: New file io, almost there, but can't compile 'write_view'
by Dan Bloomquist 08 Dec '18

08 Dec '18

So, I had to deal with a lib I worked on last a couple of years ago. Great news, the file IO has been greatly simplified in 1.68. I was able to retire several dozens of cryptic,(for me), lines. The old code won't compile as the Adobe extensions are gone. I'm almost there, I can read files, but I don't understand why I can't get the writer to compile. I get to my code, in case it matters: bg::rgb8_image_t destImg( res, x ); resize_view( view( sourceImg ), view( destImg ), bg::bilinear_sampler( ) ); and rgb8_image_t should be a good one from what I read: <https://www.boost.org/doc/libs/1_68_0/libs/gil/doc/html/io.html> With either: bg::write_view( path_to, destImg, bg::jpeg_tag() ); or: bg::image_write_info<bg::jpeg_tag> write_setttings; bg::write_view( path_to, destImg, write_setttings ); ms140 complains: 1>C:\cpp\boost_1_68_0\boost/gil/extension/toolbox/metafunctions/get_pixel_type.hpp(33): error C2039: 'reference': is not a member of 'boost::gil::image<boost::gil::rgb8_pixel_t,false,std::allocator<unsigned char>>' 1> c:\cpp\boost_1_68_0\boost\gil\typedefs.hpp(176): note: see declaration of 'boost::gil::image<boost::gil::rgb8_pixel_t,false,std::allocator<unsigned char>>' 1> console_test.cpp(248): note: see reference to class template instantiation 'boost::gil::get_pixel_type<boost::gil::rgb8_image_t>' being compiled 1>C:\cpp\boost_1_68_0\boost/gil/extension/toolbox/metafunctions/get_pixel_type.hpp(34): error C2146: syntax error: missing '>' before identifier 'reference' What am I missing? Do I need to supply more information? I'll put the whole thing in a url if needed. Thanks, Dan.

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[release] Boost 1.69.0 Release Candidate 1
by Marshall Clow 07 Dec '18

07 Dec '18

The release candidates for the 1.68.0 release are now available at: <https://dl.bintray.com/boostorg/release/1.69.0/source/> The SHA256 checksums are as follows: af05616f71006f97833e130aad886c96136457511ace4b5496d6566e69cbe0ca boost_1_69_0_rc1.7z 8f32d4617390d1c2d16f26a27ab60d97807b35440d45891fa340fc2648b04406 boost_1_69_0_rc1.tar.bz2 9a2c2819310839ea373f42d69e733c339b4e9a19deab6bfec448281554aa4dbb boost_1_69_0_rc1.tar.gz d074bcbcc0501c4917b965fc890e303ee70d8b01ff5712bae4a6c54f2b6b4e52 boost_1_69_0_rc1.zip 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. -- The Boost Release Managers

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error_code using c++11 and boost
by Lars 07 Dec '18

07 Dec '18

Hello, A project that uses Boost 1.6X (filesystem, uuid, asio) and C++14 on multiplatform. Does it make sense to use std::error_code in this project ? The concern is compatibility between boost and std. The filesystem_error exception will return a boost ::system::error_code which is not compatible with std::error_code as far as I can tell. Exception is not an option. Would it be possible for boost to implement some sort of convertion method from boost::system::error_code to std::errror_code? Thanks kind regards, Lars

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Re: [Boost-users] error_code using c++11 and boost
by Bjorn Reese 06 Dec '18

06 Dec '18

On 11/16/18 4:06 PM, Lars via Boost-users wrote: > Would it be possible for boost to implement some sort of convertion > method from boost::system::error_code to std::errror_code? The upcoming 1.69 release of Boost.System has built-in support for std::error_code. If you need to use earlier versions, then you can create a bridge between the two: http://breese.github.io/2016/06/18/unifying-error-codes.html

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[Spirit] How to prohibit reserved names from matching
by Michael Powell 06 Dec '18

06 Dec '18

Hello, Let's say I have some Qi rules: qi::rule<It, char()> mych; qi::rule<It, std::string()> myname; struct reserved_names_t : qi::symbols<path_t, path_t> { reserved_names_t() { this->add("CON", "CON") ("PRN", "PRN") ("AUX", "AUX") ("NUL", "NUL") ("COM1", "COM1") ("COM2", "COM2") ("COM3", "COM3") ("COM4", "COM4") ("COM5", "COM5") ("COM6", "COM6") ("COM7", "COM7") ("COM8", "COM8") ("COM9", "COM9") ("LPT1", "LPT1") ("LPT2", "LPT2") ("LPT3", "LPT3") ("LPT4", "LPT4") ("LPT5", "LPT5") ("LPT6", "LPT6") ("LPT7", "LPT7") ("LPT8", "LPT8") ("LPT9", "LPT9") ; } } reserved_names; Assuming I've defined mych accordingly, the simple approach would be: myname %= +myname; This gets me the name in the character set. Now, I want to prohibit the reserved names from matching. myname %= ~qi::no_case[reserved_names] | +myname; However, this does not seem to work. I suppose it is one thing ruling out invalid characters, but what about prohibiting whole strings? Thanks in advance for any insights... Michael Powell

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LLVM bitcode for Boost libraries?
by Osman Zakir 06 Dec '18

06 Dec '18

I want to build a project I have, which has to link against Boost.System, to WebAssembly, and it seems like I have to generate LLVM bitcode for it first. Is it possible to use the bootstrapper that comes with the Boost distribution to do this on Windows 10? The project in question is on GitHub here: https://github.com/DragonOsman/currency_converter . I switched out the Asio in the Boost distribution with the official Emscripten port of Asio, found here: https://github.com/emscripten-ports/asio . But I don't know which version of Boost.Asio it's using so I'd like some clarification on that if possible (I opened this issue there: https://github.com/emscripten-ports/asio/issues/2 and have just now updated the question to ask what version of Asio is being used for the port). [https://avatars0.githubusercontent.com/u/18173932?s=400&v=4]<https://github.com/emscripten-ports/asio/issues/2> Update of Asio port? · Issue #2 · emscripten-ports/asio<https://github.com/emscripten-ports/asio/issues/2> Sorry if this is an unwelcome question, but I want to ask if there'll ever be an update to this port of Asio to Emscripten/WebAssembly. I notice it's from 2015. Which version of Boost is it... github.com [https://avatars1.githubusercontent.com/u/8116924?s=400&v=4]<https://github.com/emscripten-ports/asio> GitHub - emscripten-ports/asio<https://github.com/emscripten-ports/asio> Join GitHub today. GitHub is home to over 28 million developers working together to host and review code, manage projects, and build software together. github.com [https://avatars0.githubusercontent.com/u/18173932?s=400&v=4]<https://github.com/DragonOsman/currency_converter> GitHub - DragonOsman/currency_converter: Application for Computer Science course<https://github.com/DragonOsman/currency_converter> Google Maps + Currency Converter Web Application. Application for Computer Science course. This is a currency converter web application with the frontend and a backend. github.com

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Boost.Beast vs Boost.Asio
by Cristian Morales Vega 04 Dec '18

04 Dec '18

There are lots of things which I would expect to be in Boost.Asio which are actually in Boost.Beast. Why? Most of it is "helping" code/docs. For example: - Documentation about (and public interfaces to simplify) the creation of composed operations https://www.boost.org/doc/libs/develop/libs/beast/doc/html/beast/using_io/w… - beast::buffers_cat - beast::test::stream (to be fair, it's in experimental) But now we even have code to work around issues in Boost.Asio which ideally would simply be fixed in Boost.Asio. For example: beast::ssl_stream. I'm personally using all of the above, they are extremely useful. I just supposed it is because there is only one person working on Boost.Asio, and Christopher must be quite busy with life and getting Networking TS into the standard. I was hoping all this would go away by 2020 and I was ignoring the issue. But since now it seems Networking TS will have to wait for 2023... well, I am asking myself how to handle an increasing amount of references to Beast that in a future could change to Asio (potentially with slightly different names/semantics). So I am writing this hoping for some light on the situation.

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Re: [Boost-users] [asio] UDP recv error handling
by Bjorn Reese 03 Dec '18

03 Dec '18

On 11/22/18 3:44 PM, Klebsch, Mario via Boost-users wrote: > Are there any recommendations on how to decide, whether the receive > callback function should re-initiate a receive operation after a receive > error or not? Unlike TCP, UDP does not establish a connection. By default you will not receive any network errors on a UDP socket. You have to call connect() on the socket in order to receive (ICMP) error messages, but this has other implications. With UDP it is more common to rely on application layer error messages and/or timeouts.

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Monitor OSX kqueue descriptor for events with ASIO
by Blaine Walls 02 Dec '18

02 Dec '18

Hi all, I'm using boost::asio on OS X. I'd like to watch for changes to a particular regular file - per Apple's documentation, the preferred method for this is with the kevent API. So I do the following: 1) Wrap a kqueue file descriptor (obtained via a call to kqueue()) in a boost::asio::posix::stream_descriptor with boost::asio::posix::stream_descriptor::assign(). 2) Call boost::asio::posix::stream_descriptor::async_wait() to be notified of file events. The problem appears to be that boost::asio::posix::stream_descriptor::async_wait() uses ioctl() w/ FIONBIO to put the file into non-blocking mode, which fails with "Inappropriate ioctl for device". A normal blocking call to wait() works just fine. I realize that my problem is that the kqueue descriptor does not represent a stream of bytes, so it's probably invalid to use stream_descriptor to wrap it. Does anyone have any ideas on how to work around this? I looked for a type concept for a non-stream descriptor that I could implement, but I didn't see anything obvious. Thanks in advance for any advice, -Blaine

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boost/units - converting forces (lbf->N)
by Matt Vinson 01 Dec '18

01 Dec '18

To see if I understand the library, I want to create metric and imperial systems without using Boost Units predefined systems*. Conversions between lengths are going well. Conversion between forces are going well until pounds-force to newtons; line 182 in the link. What am I doing wrong when lbf will not convert to newtons? Here is my code: https://coliru.stacked-crooked.com/a/f5f80d39fbdf8013 Any help is appreciated. * //imperial namespace boost {namespace units { namespace us {}}}//sinamespace boost { namespace units { namespace si {}}}

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Boost on Android-ndk
by Philip_liu 30 Nov '18

30 Nov '18

Hi everyone, I want to build a boost on android-ndk in ubuntu18.04,I had tried boost 1.58 and 1.68 on android-ndk r10e r13b r15c,and all failed at the step "./b2 \"with error"version 'xx' of default 'g++' does not match".Hope to know how to solve the problem or tell me how to install successfully with the right version in ubuntu18.04. Best Regard, Philip Liu

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[Spirit] Qi Symbols mapping to AST enum
by Michael Powell 28 Nov '18

28 Nov '18

Hello, I've got a qi::symbols capturing some built-in types. At the moment, I gather, they are mapped to std::string. However, I would rather map them to an AST level enum. For instance, struct builtin_type_t : qi::symbols<char, std::string> { builtin_type_t() { this->add("double", "double") ("float", "float") // ... ; } } builtin_type; Instead, namespace ast { enum type_t { type_double, type_float /* , ... */ }; } struct builtin_type_t : qi::symbols<char, ast::type_t> { builtin_type_t() { this->add("double", ast::type_double) ("float", ast::type_float) // ... ; } } builtin_type; I assume this is possible? Am I missing something about that? Thanks! Michael Powell

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Boost intrusive list volatile hook
by nat ersoz 26 Nov '18

26 Nov '18

I intend to use the boost intrusive list to implement an observer pattern. - The list will cross interrupt boundaries; meaning one interrupt will produce the notifications and the other interrupt will observer the notifications. - The observer, in response to a notification, might detach itself from the list using the the hook's unlink() function. - I think that I will need the hook to be declared volatile in order to accommodate this. I have a minimal code sample here: https://github.com/natersoz/patterns/blob/master/observer/intrusive_list_me… My list hook member declaration: using list_hook_type = boost::intrusive::list_member_hook< boost::intrusive::link_mode<boost::intrusive::auto_unlink> >; list_hook_type hook; My list declaration: using list_type = boost::intrusive::list< Observer<NotificationType>, boost::intrusive::constant_time_size<false>, boost::intrusive::member_hook< Observer<NotificationType>, typename Observer<NotificationType>::list_hook_type, &Observer<NotificationType>::hook> >; If I a the volatile keyword to the list hood type, I cannot figure out how to get the list_type declaration to fit into the list template list. Is it possible? Thank you. -- Nat Ersoz 425-417-5182 (cell)

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Re: [Boost-users] Interprocess: limited boost::any in shared memory
by Ferguson, Neil D CTR (US) 26 Nov '18

26 Nov '18

Mr. de Vries, std::variant looks like it should work splendidly. boost::variant might be even better. Thank you. BTW: this is my first user group interaction; I hope I am responding correctly. Neil Ferguson -----Original Message----- From: Maarten de Vries [mailto:maarten@de-vri.es] Sent: Wednesday, November 21, 2018 1:06 PM To: boost-users(a)lists.boost.org Cc: Ferguson, Neil D CTR (US) <neil.d.ferguson.ctr(a)mail.mil> Subject: [Non-DoD Source] Re: [Boost-users] Interprocess: limited boost::any in shared memory All active links contained in this email were disabled. Please verify the identity of the sender, and confirm the authenticity of all links contained within the message prior to copying and pasting the address to a Web browser. ________________________________ On Wed, 21 Nov 2018 at 20:58, Ferguson, Neil D CTR (US) via Boost-users <boost-users(a)lists.boost.org < Caution-mailto:boost-users@lists.boost.org > > wrote: Sirs and madams, I hope to use boost interprocess shared memory to pass complex and dynamic data structures between processes on a host efficiently. The structures will be comprised only of simple primitives (int, float, etc.), interprocess basic_string, interprocess containers (vectors and maps), containers of containers, and (possible deal killer) boost::any. From the interprocess documentation, it _looks_ like the preceding is doable, aside from boost::any. The boost::any objects will themselves contain only primitives, basic_string, or interprocess vectors of unsigned char. So it _looks_ like the data held by the any should be okay. My question: does boost::any use pointers, references, or other constructs that preclude the class from working in shared memory? Thanks for your advice. Neil Ferguson Take a look at /usr/include/boost/any.hpp . You will see that the actual content of the any object is a pointer created with `new` and cleaned up with `delete`. So this will not work properly in shared memory. You could consider using std::variant instead, which does not put storage on the heap (unless contained objects do it themselves, of course). Kind regards, Maarten de Vries

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IOStream: Determine number of bytes written to array sink
by Peter Klotz 23 Nov '18

23 Nov '18

Hello The program below decompresses a std::string using Boost.IOStream. The target is an array sink of fixed size. The users know the decompressed size in advance but for security reasons I need to check the number of bytes written to the sink. If the array is too small, a "write area exhausted" exception is thrown, which is fine. If the array is too big, decompression succeeds. I would like to check the number of bytes written to the sink and throw an exception. How can I determine how many bytes have been written to the sink? Btw: I cannot use the "counter" filter because of the overhead involved in line counting and because the return value of its characters() method is "int". The buffers involved in my application require a 64 bit data type. Private base class basic_zlib_decompressor of class basic_gzip_decompressor has method total_out() which seems to return the value in question but its return type is also only an "int". Regards, Peter. #include <iostream> #include <stdexcept> #include <iomanip> #include <boost/iostreams/filtering_streambuf.hpp> #include <boost/iostreams/device/array.hpp> #include <boost/iostreams/filter/gzip.hpp> void decompress(const std::size_t p_bufferSize) { // decompressed string is "xy" const std::string s("\x1f\x8b\x08\x08\x58\xce\xf6\x5b\x02\x03\x78\x79\x00\xab\xa8\x04\x00\x99\x28\xe6\x8f\x02\x00\x00\x00",25); boost::iostreams::filtering_streambuf<boost::iostreams::output> filteringStreambuf; filteringStreambuf.push(boost::iostreams::gzip_decompressor()); const std::unique_ptr<char[]> buffer=std::make_unique<char[]>(p_bufferSize); filteringStreambuf.push(boost::iostreams::array_sink(buffer.get(),p_bufferSize)); boost::iostreams::write(filteringStreambuf,s.c_str(),s.size()); boost::iostreams::close(filteringStreambuf); } int main() { try { decompress(3); // works, although only 2 bytes are required, should be made to fail //decompress(2); // works, exactly fills the buffer //decompress(1); // throws exception "write area exhausted" as expected return 0; } catch (const std::exception& e) { std::cout << e.what() << std::endl; } return 1; }

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Overcoming AST forward declaration (includes online example)
by Michael Powell 23 Nov '18

23 Nov '18

Hello, Please find the example posted here: http://wandbox.org/permlink/NI2Luvrw1HF7lF1E The couple of concerns I have in question at the moment are: * How to best handle variants throughout the grammar. Can I use std::variant? Do I need to use boost::variant? Are there additional Spirit features that make this doable? * Embedded in that question is what to do with "nil" or "empty statements" which occurs throughout the grammar at times. I wondered if "empty statement" could synthesize "nothing", literally, not contribute to a variant alternative, for instance. Other AST examples seemed to inject a "struct nil {}" pattern, so I figured maybe this was the better approach? * The real kerfuffle for me at the moment is the AST forward declaration. From what I gather in the protocol, this is an absolute must have. It most occur before Group, and is also used by Message. Thoughts? Suggestions? And, please, before you suggest there are "proto compilers" already available: yes, I know, I've been down that road. I am not looking to parse the proto itself, per se, but rather do some code generation for target language artifacts other than the proto itself. Toward which end, I am also investigating a protoc compiler plugin approach. But I figured, I'd pursue this as a viable path to solving the problem as well, notwithstanding the above challenges. Thanks in advance! Cheers, Michael Powell

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Boost::Filesystem - Handling Unicode paths
by Richard Závodný 22 Nov '18

22 Nov '18

Hello, I have another problem. My program now failing when I want iterate directory which contain files with Unicode characters in it's name. Is there something I should know about? Also I want it to work on both Windows and POSIX platforms, even though I don't expect Unicode characters in POSIX enviroment. Thank you.

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[Spirit] parsing double precision issues
by Michael Powell 22 Nov '18

22 Nov '18

Hello, I am continuing to work through my Protobuf parsing with Constant/Floating-Point tests. Double precision is rearing its ugly head and I am curious what's the best way to handle potentially determining a healthy epsilon given the expected parsed value. For the most part, I think it's going to work, but for the precision issues. Catch: REQUIRE( actual == expected ) with expansion: struct my::protobuf::ast::floating_point_t { 'val': 1.16624e+306, 'opt_sign': null } == struct my::protobuf::ast::floating_point_t { 'val': 1.16624e+306, 'opt_sign': null } with messages: Source: syntax = 'proto2';option L = 1.16624e+306; Delta was: 2.35309e+300 There was clearly a delta involved, most like a precision issue encountered during the parse. Without going into a great deal of depth, if possible: namespace my { namespace protobuf { namespace ast { using float_t = double; enum num_sign_t { sign_none /// '-' , sign_minus /// '+' , sign_plus }; // Which includes struct floating_point_t : numeric_t<float_t> { /* ... */ }; } } } // Without sign, dot required. // >>> TODO: TBD: Precision issue? Or an actual double parsing issue? <<< float_lit %= real_parser<ast::float_t, strict_ureal_policies<ast::float_t>>{}; floating_point_lit %= -num_lit_sign >> float_lit; qi::rule<It, ast::num_sign_t()> num_lit_sign; qi::rule<It, ast::float_t()> float_lit; qi::rule<It, ast::floating_point_t()> floating_point_lit; https://developers.google.com/protocol-buffers/docs/reference/proto2-spec#f… https://developers.google.com/protocol-buffers/docs/reference/proto2-spec#c… https://www.boost.org/doc/libs/1_68_0/libs/spirit/doc/html/spirit/qi/refere… Cheers, Michael Powell

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[asio] UDP recv error handling
by Klebsch, Mario 22 Nov '18

22 Nov '18

Hello, When using boos asio async receiving, my received callback usually looks like this: void ReceiveCB(const boost::system::error_code& error, std::size_t bytes_transferred) { If (error) { fprintf(stderr, "recv() failes: %s\n", error.message().c_str()); return; } /* process data received */ s.async_receive( boost::asio::buffer(...), & ReceiveCB); } I stop calling async_receive() as soon as I get an error. This works good for TCP sockets. But with UDP sockets, recvfrom() can return e.g. the error 'connection refused' after I called sendto() to a peer machine, where no socket is (yet) bound to the destination port number. So, at least after the error 'connection refuxed', I'd better continue calling async_receive_from(). Are there any recommendations on how to decide, whether the receive callback function should re-initiate a receive operation after a receive error or not? Mario Klebsch -- Mario Klebsch Actia I+ME GmbH Mario.klebsch(a)ime-actia.de<mailto:Mario.klebsch@ime-actia.de> Dresdenstrasse 17/18 Fon: +49 531 38 701 716 38124 Braunschweig Fax: +49 531 38 701 88 Germany

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Interprocess: limited boost::any in shared memory
by Ferguson, Neil D CTR (US) 21 Nov '18

21 Nov '18

Sirs and madams, I hope to use boost interprocess shared memory to pass complex and dynamic data structures between processes on a host efficiently. The structures will be comprised only of simple primitives (int, float, etc.), interprocess basic_string, interprocess containers (vectors and maps), containers of containers, and (possible deal killer) boost::any. From the interprocess documentation, it _looks_ like the preceding is doable, aside from boost::any. The boost::any objects will themselves contain only primitives, basic_string, or interprocess vectors of unsigned char. So it _looks_ like the data held by the any should be okay. My question: does boost::any use pointers, references, or other constructs that preclude the class from working in shared memory? Thanks for your advice. Neil Ferguson

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