December 2018 - Boost-users - lists.preview.boost.org

[interprocess] Determine size of managed_shared_memory
by Kai Benndorf 12 Oct '19

12 Oct '19

Hi all, I want to create a managed_shared_memory in exactly the size I needed. Therefore I do something like this: size = sizeof( common_managed_shared_memory ); size += sizeof( MyClassInSharedMem ); managed_shared_memory segment(create_only, "name", size ); MyClassInSharedMem allocates itself some memory by segment->allocate(). I added this also to the size, but get a boost::interprocess::bad_alloc exception on allocating this additional memory. Are there some magic bytes I forgot to add? Many thanks in advance Kai

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boost::filtered_graph filtering on vertex color... if I only had a colormap
by Brian Davis 19 Jul '19

19 Jul '19

Lets say I have a graph g (of type graph_t) and a color map (boy I wish I had a colormap): typedef boost::property_map<graph_t, boost::vertex_color_t>::type color_map_t; or is it? auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::default_color_type>(indexmap); or maybe? auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::vertex_color_t>(indexmap); or possibly some goop found on the internet? boost::make_iterator_property_map(color_map.begin(), boost::get(boost::vertex_index, data_->g), color_map[0]) or other internet goop? typedef boost::property_map<GraphType, boost::vertex_color_t>::type color_map_t; color_map_t colorMap; boost::color_map(colorMap)) or other internet goop?? std::vector<int> colorMap(num_vertices(g), boost::white_color); so confused... (certainly not surprised why bgl is not a part of stl) Can someone help explain the various types and ways of specifying colormaps and the logic for each way and means? and a function (if I could get that far without VS syntax highlighter going bonkers and gobs of compiler errors.. you know the type): make_pretty(g, colormap ) which colors the graph colormap and a filter struct for boost::filtered_graph<Graph, EdgePredicate, VertexPredicate> (where I wonder why if I only want to filter vertices I have to set boost::keep_all for EdgePredicate... sigh... I know the answer... and also know how long it found me to find/figure out boost::keep_all - and if you are looking for boost::keep_all and found it here... your welcome ;-) ) and modifying (probably incorrectly) boost::filtered_graph example to: template <typename ColorMap> struct vertex_color_filter_eq { vertex_color_filter_eq() { } vertex_color_filter_eq(ColorMap colormap/*, boost::default_color_type c*/) : m_colormap(colormap)/*, m_c(c)*/ { } template <typename Vertex> bool operator()(const Vertex& v) const { return 0 < get(m_colormap, v); //return c < get(m_colormap, v); } ColorMap m_colormap; //boost::default_color_type m_c; }; auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::default_color_type>(indexmap); // some where here I would call make_pretty(g, colors) typedef property_map<graph_t, boost::vertex_color_t>::type ColorMap_t; vertex_color_filter<ColorMap_t> filter(colors); // boost::filtered_graph<graph_t, boost::keep_all, VertexPredicate> boost::filtered_graph<graph_t, boost::keep_all, vertex_color_filter> fg(g, filter); // Later say if I could get it compile and better if it compiled and worked I could move on and auto color = boost::red_color; typedef property_map<graph_t, boost::vertex_color_t>::type ColorMap_t; vertex_color_filter<ColorMap_t> filter(colors, color); boost::filtered_graph<graph_t, boost::keep_all, vertex_color_filter> fg(g, filter); Maybe if I color them yellow, I can then reach the wizard pull back the curtain and ask how to create a color map... If I only had a color map.

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Question on Posix timezone string
by Mats Webjörn/WIKAB 10 Mar '19

10 Mar '19

I'm using Boost 1.66 and use the following code to get a Posix string to set my uCLinux TZ environment variable to get a local time from an UTC time #include <boost/date_time/local_time/tz_database.hpp> #include <boost/date_time/local_time/local_time.hpp> tz_database tz_db; tz_db.load_from_file("./date_time_zonespec.csv"); time_zone_ptr nyc = tz_db.time_zone_from_region("Europe/Stockholm"); auto s = nyc->to_posix_string(); // "CET+01CEST+01,M3.5.0/02:00,M10.5.0/03:00" setenv("TZ", s.c_str(), 1); The odd thing is that my localtime becomes incorrect, and is actually 1 hr wrong on the opposite side of UTC. But, when I read https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html it says "The offset specifies the time value you must add to the local time to get a Coordinated Universal Time value". Not add to UTC time, which seems like the Boost Posix string assumes !!!!! Which explains why 16:00 UTC give 15:00 CET instead of 17:00 which is the correct value, when using localtime_r(). Am I missing something fundamentally, or what? Regards Mats Webjörn Webjörn IngenjörsKonsult AB Solhemsbackarna 75A SE-163 56 SPÅNGA Sweden

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Boost Test thread safety
by Dan Field 21 Feb '19

21 Feb '19

Hi folks: I'm trying to identify whether or not the boost Test library is thread safe in the sense that multiple threads can simultaneously interact with the library's various macros and API. I'm more interested in a single test being multi-threaded than being able to run multiple test cases simultaneously. In early documentation of the Test library (version 1.58.0 and before) , there's a section in the introduction called "Open issues" that indicates that the library is not thread-safe. However, the documentation after 1.58.0 was substantially re-written, and I don't see any discussion regarding thread safety at all. The question remains. is the Test library thread-safe or not? If there is a definitive statement regarding this issue, please let me know. Thanks in advance!

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[boost.test] Colors
by Udo Steinbach 20 Feb '19

20 Feb '19

Ahoi! I use boost.test and have now updated to boost v1.68 on Windows, working in standard console. Now Test has colored output, YEAH. The result you see in the picture https://www2.pic-upload.de/img/36193998/no_error_detected.png Notice that I don't use the standard color scheme. With set BOOST_TEST_COLOR_OUTPUT=1 text is light green on gray, bad to read. set BOOST_TEST_COLOR_OUTPUT=0 does black on gray. After that the colors are set to my scheme. Now error result with set BOOST_TEST_COLOR_OUTPUT=1: https://www2.pic-upload.de/img/36193997/failure.png Light red on gray, OK to read, but reset to dark red on gray. I have to use the color command to reset the colors. With command line options it's all the same. Hmmm, how useful can colors be, if the standard output (no error detected) is only one short line? Both pics on https://www.pic-upload.de/gal-1197957/om664y/1.html -- Fahrradverkehr in Deutschland: http://radwege.udoline.de/ GPG: A245 F153 0636 6E34 E2F3 E1EB 817A B14D 3E7E 482E

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ASIO: Writing Composed Operations
by Cristian Morales Vega 26 Jan '19

26 Jan '19

Hi, I was looking at https://www.boost.org/doc/libs/develop/libs/beast/doc/html/beast/using_io/w… and came up with a question I can't answer: In https://github.com/boostorg/beast/blob/develop/example/echo-op/echo_op.cpp#… why does it use the AsyncStream associated executor without even looking at the potentially different (right?) Handler associated executor? Regards.

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C++/CLI and >=VS2015
by liong＠gmx.ch 09 Jan '19

09 Jan '19

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ASIO vs Beast DynamicBuffer use
by Cristian Morales Vega 02 Jan '19

02 Jan '19

Hi, I have just noticed that while ASIO passes DynamicBuffers as && (https://www.boost.org/doc/libs/1_68_0/doc/html/boost_asio/reference/async_r…) Beast passes them via reference (https://www.boost.org/doc/libs/1_68_0/libs/beast/doc/html/beast/ref/boost__…) I'm guessing this happens because ASIO thinks you are going to use dynamic_string_buffer/dynamic_vector_buffer as DynamicBuffer, while Beast thinks you are going to use flat_buffer/multi_buffer. In the second case doesn't make sense to give ownership of the DynamicBuffer to the initiation function because then you would not be able to look at the received data when the operation completes. Since ASIO DynamicBuffer implementations are just adaptors over string/vectors that you keep, it makes sense to move those adaptors, you still keep the string/vector with the data. Have I got it right? But this raises the question: what should I use in my own initiating functions? Regards.

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function template with a universal reference to a specific type
by Ireneusz Szcześniak 01 Jan '19

01 Jan '19

Hi, I'm writing to ask a C++ question, not specifically Boost-related, but this list is the best place I know. How can I write a function template, which has a parameter of the universal reference to a specific type? I can write a function template like this: template <typename T> void foo(T &&t) { // The primary template implementation. cout << "Primary: " << __PRETTY_FUNCTION__ << endl; } And so I can call this function with an expression of any value category, and any type, cv-qualified or not, like this: int main() { foo(1); int i = 1; foo(i); const int ci = 1; foo(ci); } In my code I need to provide different implementations of foo for different types (and these types are templated). How can I accomplish that? Best, Irek

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Error: no member named 'GetModuleFileNameA' in namespace 'boost::winapi'; did you mean simply 'GetModuleFileNameA'?
by Osman Zakir 31 Dec '18

31 Dec '18

Hi again, everyone. When trying to build Boost 1.69.0 after having placed my installation of Python 3.7.1 above the one of Python 2.7.15, I got the error mentioned in the title of this email. It says at the end, " ...failed updating 4 targets... ...skipped 8 targets... ...updated 2381 targets... " The project-config.jam file I used is attached to this message.

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Errors with 1.69 when compiling with /clr on MSVC
by Stian Zeljko Vrba 30 Dec '18

30 Dec '18

I get the following warning and error when compiling a C++/CLI file that includes boost 1.69. 1>c:\quinesoftwarebase\include\boost\type_traits\detail\is_member_function_pointer_cxx_11.hpp(114): error C2764: 'C': template parameter not used or deducible in partial specialization 'boost::is_member_function_pointer<Ret(Args...)>' 1>c:\quinesoftwarebase\include\boost\type_traits\detail\is_member_function_pointer_cxx_11.hpp(125): warning C4575: '__vectorcall' incompatible with the '/clr' option: converting to '__stdcall' Is there a workaround for this? -- Stian

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Re: [Boost-users] [cfe-dev] [llvm-dev] Error: ISO C++17 does not allow 'register' storage class specifier [-Wregister], when building Boost 1.69.0
by Osman Zakir 25 Dec '18

25 Dec '18

I'll build using C++14 mode, then. I wonder if Python 3.7.1 has this issue as well? If it doesn't, then maybe Boost should switch over to that version of Python. ________________________________ From: Matthieu Brucher <matthieu.brucher(a)gmail.com> Sent: Tuesday, December 25, 2018 2:56 PM To: Oleg Smolsky Cc: Craig Topper; Osman Zakir; clang developer list; cfe-users(a)lists.llvm.org; llvm-dev(a)lists.llvm.org Subject: Re: [cfe-dev] [llvm-dev] Error: ISO C++17 does not allow 'register' storage class specifier [-Wregister], when building Boost 1.69.0 The issue comes in part form the Python headers that have the keyword. Unfortunately, this also means that there is an issue while building user code. But it's not a Boost code issue for this library, but a Python one. Regards, Matthieu Le mar. 25 déc. 2018 à 02:08, Oleg Smolsky via cfe-dev <cfe-dev(a)lists.llvm.org<mailto:cfe-dev@lists.llvm.org>> a écrit : Yes, this keyword is no longer valid starting from C++17: https://en.cppreference.com/w/cpp/keyword/register I realize that the "why" probably doesn't help you move forth with your problem, so here are a couple suggestions how to get over it: * Build Boost in C++14 mode with -std=c++14 * Cut out "register" from the Boost source and rebuild * Try a newer Boost version, it may have been fixed Oleg. On 2018-12-23 09:26, Craig Topper via cfe-dev wrote: This seems a better question for cfe-dev or cfe-users ~Craig On Sat, Dec 22, 2018 at 12:23 PM Osman Zakir via llvm-dev <llvm-dev(a)lists.llvm.org<mailto:llvm-dev@lists.llvm.org>> wrote: When trying to build Boost using LLVM, I had this error: " error: ISO C++17 does not allow 'register' storage class specifier [-Wregister] " I attached the project-config.jam file I used to this message. Someone please help me out (if there's someone on here who can). _______________________________________________ LLVM Developers mailing list llvm-dev(a)lists.llvm.org<mailto:llvm-dev@lists.llvm.org> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev _______________________________________________ cfe-dev mailing list cfe-dev(a)lists.llvm.org<mailto:cfe-dev@lists.llvm.org> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev _______________________________________________ cfe-dev mailing list cfe-dev(a)lists.llvm.org<mailto:cfe-dev@lists.llvm.org> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev -- Quantitative analyst, Ph.D. Blog: http://blog.audio-tk.com/ LinkedIn: http://www.linkedin.com/in/matthieubrucher

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Problem downloading 1.69.0 for Windows
by tim＠raisedbar.net 24 Dec '18

24 Dec '18

Hi, Windows Defender is blocking my download from https://www.boost.org/users/history/version_1_69_0.html as it is identified as being unsafe. Can anybody advise, please? Best wishes. Tim Burgess Raised Bar Ltd. E: <mailto:tim@raisedbar.net> tim(a)raisedbar.net M: +44 (0)7989 486976

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[Asio/Beast] Any non-obvious reasons for no bind_executor_and_allocator?
by Sorin Fetche 23 Dec '18

23 Dec '18

Hi, As I'm looking to modernize an older C++03 project based on Boost.Asio to use C++17 and the net TS api, I am not ready yet to give up on using lambdas for completion handlers. Boost.Asio and Boost.Beast have some utilities for correctly implementing asynchronous composed operations but from them only asio::bind_executor seems to be applicable to lambdas. And the problem is that it only associates an executor with a (lambda) object; I didn't find any utility for associating an allocator too. Could there be any reason for a utility that associates both an executor and an allocator with an object to not work correctly when implementing asynchronous operations? Or is it just that this utility has not been implemented yet? I did come across the paper "Networking TS Associations for Call Wrappers"[1], but I didn't see any mention there about bind_executor or something similar for allocators or why this kind of approach wouldn't work. I would be very happy if I could write something like: asio::post( socket_.get_executor(), bind_executor_and_allocator_from( handler_, [...] { self_.handler_(...); })); and, unless I'm missing something, such a utility could be implemented similarly to the existing asio::bind_executor. Thank you, Sorin [1] http://open-std.org/JTC1/SC22/WG21/docs/papers/2018/p1133r0.html

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Update for C++17 register keyword error question
by Osman Zakir 23 Dec '18

23 Dec '18

This is the error I get when trying to build Boost 1.69.0 with LLVM: "error: ISO C++17 does not allow 'register' storage class specifier [-Wregister]". I've also sent an email about this to the LLVM developer mailing list. I've attached the project-config.jam file to this message. Please let me know how to fix this. Thanks in advance.

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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.

1 0

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

1 0

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.

4 3

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.

2 3

[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

2 2

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

3 2

[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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