February 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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[Test] Test executable crashes always
by Nate Widmyer 26 Jun '18

26 Jun '18

Hello, I've made some unit tests with boost test before without issue, but on my latest rather ordinary test, I've been able to get Boost test to crash the executable in debug and release mode when boost test is making a report before terminating. test_exe.exe!boost::unit_test::framework::get(unsigned long id, boost::unit_test::test_unit_type t) Line 1388 C++ test_exe.exe!boost::unit_test::framework::get<boost::unit_test::test_unit>(unsigned long id) Line 208 C++ test_exe.exe!boost::unit_test::results_reporter::make_report(boost::unit_test::report_level l, unsigned long id) Line 175 C++ test_exe.exe!boost::unit_test::unit_test_main(boost::unit_test::test_suite *(*)(int, char * *) init_func, int argc, char * * argv) Line 235 C++ test_exe.exe!main(int argc, char * * argv) Line 287 C++ That's the default report_level of 'confirm' If I use report_level=short or detailed, I get a similar crash: test_exe.exe!boost::unit_test::framework::get(unsigned long id, boost::unit_test::test_unit_type t) Line 1388 C++ test_exe.exe!boost::unit_test::framework::get<boost::unit_test::test_suite>(unsigned long id) Line 207 C++ test_exe.exe!boost::unit_test::traverse_test_tree(unsigned long id, boost::unit_test::test_tree_visitor & V, bool ignore_status) Line 365 C++ test_exe.exe!boost::unit_test::results_reporter::make_report(boost::unit_test::report_level l, unsigned long id) Line 185 C++ test_exe.exe!boost::unit_test::unit_test_main(boost::unit_test::test_suite *(*)(int, char * *) init_func, int argc, char * * argv) Line 235 C++ test_exe.exe!main(int argc, char * * argv) Line 287 C++ Here's the get() method: test_unit& get( test_unit_id id, test_unit_type t ) { test_unit* res = impl::s_frk_state().m_test_units[id]; BOOST_TEST_I_ASSRT( (res->p_type & t) != 0, internal_error( "Invalid test unit type" ) ); return *res; } Crash occurs on line 2 of the function. I logged 'res' each time the function is called and many times its valid, but when it runs this one test (by itself or with others), 'res' always ends up being NULL. id seems to always be '1', and t is TUT_ANY (17) if generating a confirmation report or TUT_SUITE (16) if generating a short or detailed report. If I use the option '--report_level=no', then execution does complete fine. I followed through on some process of elimination and it seems to be related to using a fixture? Having no test body still causes the crash. It wasn't until I removed the fixture (and its usage in the body of the test) did the executable not crash. I ensured that I was using the standard fixture model found here: http://www.boost.org/doc/libs/1_64_0/libs/test/doc/html/boost_test/tests_or… OS is Win 7 w/ VS2015 boost is 1.64.0 and was built with: b2 toolset=msvc-14.0 link=static runtime-link=static variant=debug address-model=64 --without-atomic --without-container --without-context --without-coroutine --without-coroutine2 --without-graph --without-graph_parallel --without-iostreams --without-locale --without-math --without-mpi --without-serialization --without-signals --without-type_erasure --without-wave -j4 --abbreviate-paths --without-python -d2 Any help would of something to look at or change would be appreciated. Thanks for your time, Nathan

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Pointer Container Library changes in 1.66.0
by Kevin Hardman 06 Apr '18

06 Apr '18

I am seeing changes in the Pointer Container Library that are preventing my existing application from compile. I see no notice of changes in the 1.66.0 release notes <http://www.boost.org/users/history/version_1_66_0.html <http://www.boost.org/users/history/version_1_66_0.html>>. Is there documentation on the changes and what is required to migrate existing users to the new library? —kevin

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[fiber] Fiber context switching during stack unwinding...
by Oliver Seiler 01 Mar '18

01 Mar '18

(Hopefully I'm not writing an essay for something that is a gcc/libstdc++/Linux bug) I've been using Boost.Context for a number of years now, to do something similar to what Boost.Fiber does. We recently upgraded our development target environment to Debian 9 (gcc 6.3), and moved up to Boost 1.62.0, so I've been looking at Boost.Fiber to replace how we're using Boost.Context (because it looks like it could greatly simplify our code, among other things). One thing I ran into with Boost.Context was that it interacted in some interesting ways with exception handling, and I haven't really seen any discussion about it. Specifically, switching contexts with an active exception (so during stack unwinding, or in a catch block) would result in weird behaviour in the other context (std::uncaught_exception() returning true, std::current_exception() returning the exception from the other context, try/catches in the new context causing new problems when switching back to the original context which is in the middle of stack unwinding, etc). I chalked that up to limitations of the context switching, though I haven't seen any mention of avoiding context switches with active exceptions; presumably this is some interaction with gcc's exception implementation, and would maybe need support from libunwind to save/restore the exception state (I don't recall if I checked if clang produced similar results, though I'll probably give it a go when I have the chance). So I wasn't surprised when I ran into similar problems with Boost.Fiber. I am wondering why this aspect of usage isn't discussed in any of the documentation; it would be nice if these libraries could work well with language features like exceptions, but I understand that the language spec doesn't really speak to the stack switching happening under-the-hood. It actually wouldn't surprise me that this wasn't even a problem in all environments, and just happens to be an artifact of the Linux implementation, but then we're either talking about unspecified or undefined behaviour, but would be nice to know. Even in the documents going through the C++ standards committee I don't see much mention of how things like coroutines should interact with something like std::current_exception() (perhaps because it is assumed to "just work" and doesn't need additional comment?) Anyone else ever run into issues related to this? Seems like any use of RAII for exception handling would easily run into problems. Mostly I've just found ways to work around it (e.g., not allowing the context switch if std::uncaught_exception() or std::current_exception() indicate it would be unsafe to do so, typically by throwing another exception) but this tends to make libraries harder to use correctly (e.g., can't really allow context switching in a destructor, or in a function called from a destructor, etc). Cheers Oliver

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PPA for boost
by legalize+jeeves＠mail.xmission.com 28 Feb '18

28 Feb '18

[Please do not mail me a copy of your followup] Hello fellow boosters, I am one of the maintainers of the C++ language track on exercism.io. When I first implemented this language track, we didn't have good regex support in g++'s standard library yet, so we needed boost.regex to fill that gap. Since we were already going to use boost.regex, I used boost.test for the unit test support. At the time, I found a PPA that was providing prebuilt binaries for ubuntu. Since that time, the need for boost.regex has gone away because the standard library implementation has been completed for g++. Along the way, the biggest source of problems in getting people going with C++ has been boost. For Windows users, it's annoying that CMake won't "just find" boost when you install it because there's no uniform mechanism between boost, packaging and CMake to say where boost got installed. For Mac users, they end up having difficulty with homebrew and fighting with Xcode. For Linux users, the PPA has gone stale and they end up being forced to build from scratch and get sent off into a ditch. In the meantime, we've got conan at stable 1.0 version right now, but that introduces a python dependency and then a conan dependency and for beginners I don't know if that's a path less fraught with peril. We've done some work on a branch to ditch boost.test and therefore boost entirely and switch the unit test framework to Catch. We have yet to "drop the hammer" on that and bring it onto master because reasons. (I am not the developer of that branch, but I suspect it hasn't happened yet because of the other integration issues that are needed; namely a bunch of documentation has to be updated and there will be teething pains with anyone who has already downloaded existing exercises and written them against boost.test.) Now, I find it hard to believe that I am the only one that has suffered from these issues all this time. Sure, if you only use header-only libraries then you don't need to build anything, but there are more than a few libraries in boost that either require or benefit significantly from being compiled. In all this time, have we not managed to come up with a stable, reliable PPA archive with ongoing support for boost for linux users? All I seem able to find are half-heartedly maintained PPAs with stale versions of boost on them. I have even tried to navigate going about setting up my own PPA in order to solve the problem myself, but I found launchpad.net and the whole PPA process so poorly documented and explained that I couldn't make head-nor-tails of it and gave up. (And this is coming from someone who has done more than my fair share of packaging and installer work on multiple platforms.) -- "The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline> The Terminals Wiki <http://terminals-wiki.org> The Computer Graphics Museum <http://computergraphicsmuseum.org> Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

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Missing libs
by Tim Burgess 28 Feb '18

28 Feb '18

Hi, I downloaded the modular Boost master from Git Hub, as per instructions and built it on Windows as follows: .\Bootstrap .\b2 headers .\b2 This generated (amongst others) the following libs for boost::filesystem: libboost_filesystem-vc141-mt-gd-x32-1_67.lib libboost_filesystem-vc141-mt-gd-x64-1_67.lib libboost_filesystem-vc141-mt-x32-1_67.lib libboost_filesystem-vc141-mt-x64-1_67.lib I then tried to build a static release X64 version of my application using VS2017 and got: 1>LINK : fatal error LNK1104: cannot open file 'libboost_filesystem-vc141-mt-s-x64-1_67.lib' Obviously, I don't have this file, though I had thought that .\b2 was supposed to build all targets. So, I tried: .\b2 link=static This still does not generate the required file - where am I going wrong, please? BTW, I have checked that my project's library path points to the appropriate boost\stage\lib folder. Best wishes. Tim Burgess

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[Thread] Version 1.66.0 incompatible with ISOLATION_AWARE_ENABLED
by Jim Wilburn 28 Feb '18

28 Feb '18

I work on a Windows code base that I have been updating from Boost 1.64.0 to Boost 1.66.0. One of the projects sets ISOLATION_AWARE_ENABLED to 1 (refer to https://msdn.microsoft.com/en-us/library/windows/desktop/bb773175(v=vs.85).…) #define ISOLATION_AWARE_ENABLED 1 The project also includes <boost/thread.hpp>. The Windows SDK version is 10.0.16299.0. The include chain is: <boost/thread.hpp> <boost/thread/thread.hpp> <boost/thread/thread_only.hpp> <boost/thread/win32/thread_data.hpp> <boost/thread/win32/thread_primitives.hpp> <boost/detail/winapi/dll.hpp> <boost/winapi/dll.hpp> The last include contains constructions such as: BOOST_SYMBOL_IMPORT boost::winapi::HMODULE_ WINAPI LoadLibraryA(boost::winapi::LPCSTR_ lpFileName); With a nonzero ISOLATION_AWARE_ENABLED, this results in redefinition errors, e.g.: .../boost/winapi/dll.hpp(38): error C2375: 'IsolationAwareLoadLibraryA': redefinition; different linkage ...\include\10.0.16299.0\um\winbase.inl(287): note: see declaration of 'IsolationAwareLoadLibraryA' Jim Wilburn

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all roots of a polynomial
by mdebonis 22 Feb '18

22 Feb '18

Hello, I found Boost while searching for a C++ library which can do accurate polynomial root finding. The problem is that the documentation does not make it very clear how to implement this tool. Does anyone by any chance have some sample code on implementing this feature or steer me in the direction of an example in the documentation? I would like to use the best decimal place accuracy (it appears that you can get 50-place here?) Thanks! -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Users-f2553780.html

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Boost improperly including NTVERP.H
by Brian Catlin 22 Feb '18

22 Feb '18

Boost 1.66.0 is causing the Windows file NTVERP.H to be included (defining macros such as VER_DEBUG, VER_PRODUCTVERSION_STR, etc), preventing the definition of those macros by the application. This behavior didn't exist in 1.65.1, and breaks a standard Windows paradigm (it is very common for a Windows program to have a Version.h file containing the version resource macros (that are also defined in NTVERP.H), and then include Version.h in the main CPP file and the Resources.RC file). The NTVERP.H file contains the version information for the Windows SDK, and should NOT be included in an application! NTVERPH.H is included in: boost.1.66.0.0\lib\native\include\boost\predef\platform\windows_uwp.h boost.1.66.0.0\lib\native\include\boost\winapi\config.hpp

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compilation error
by Dk Jack 21 Feb '18

21 Feb '18

Hi, I am getting a compilation error when trying to compile my app. I've detailed my issue on stack overflow. https://stackoverflow.com/questions/48897103/compile- error-in-boost-header-file-fails-on-centos-7-compiles-on-ubuntu-16-04 Would appreciate if someone here can provide some guidance on how to resolve it. Thanks. D.

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Serialization of optional<std::string>
by Chardrazle 21 Feb '18

21 Feb '18

As part of upgrading a product to a later version of boost the compilation has tripped up on serialization of a boost::optional<std::string>. The /optional.hpp/ header now has the comment: ...and this fires for std::string. What, if any, is the recommended way forward for this? An example code snippet to illustrate: Previous version of boost: 1.50; new: 1.6x Compiling with g++ 4.6.4 (although same problem with 4.8.5): -W -Wall -std=c++0x... (The real code is actually using the portable_binary_archive, but let's avoid muddying the waters at this stage :) -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Users-f2553780.html

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Math and numerics: Odeint - problem with adaptive step size
by William Heitler 20 Feb '18

20 Feb '18

Hello, I'm a moderately experienced C++ programmer using Visual Studio 2017, but I'm new to using the boost odeint library. I'm trying to integrate the Hodgkin-Huxley equations, which are a set of ODEs that describe the generation of nerve impulse. The output should be a time-series waveform which is mainly flat but with occasional spikes in it. I have a functor HH which works fine with a standard fixed-step Runge-Kutta routine runge_kutta4< state_type > stepper; integrate_const(stepper, HH, x, 0.0, 20.0, 0.04,trace_observer()); This code produces exactly the right waveform However, I would like to use an adaptive step size because the waveform is pretty flat between the spikes. I tried the following: integrate_adaptive(make_dense_output(1.0e-6, 1.0e-6, runge_kutta_dopri5< state_type >()), hh, x, 0.0, 10.0, 0.04, trace_observer()); This works up to about the peak of the first spike, but then crashes with the error message: Debug Assertion Failed! ... Expression: vector iterator not incrementable It dies in the Visual Studio vector library code _Vector_const_iterator& operator++() in a call from boost::norm_inf where iterator first1 reports as first1 {2.105352686232e-314#DEN} std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<double> > > I certainly don't understand how the boost code works under the hood, but I wondered if anyone could suggest a change in my calling code that might make it work? I have hand-crafted some adaptive step size code which works OK (and does run faster than the fixed step size), but it is a bit of a kludge and I would rather use code developed by people who actually understand the maths. For reasons of brevity I haven't put the HH code in this message, but could do if it would help. Thanks for any help Dr W J Heitler School of Biology University of St Andrews 01334 463490 www.st-andrews.ac.uk/~wjh<http://www.st-andrews.ac.uk/~wjh>

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[Iostreams] Known issue with 32-bit and iostreams::file_descriptor_sink?
by Tim Landscheidt 19 Feb '18

19 Feb '18

Hi, I'm trying to debug several issues in ledger (https://www.ledger-cli.org/) under Fedora 26 (boost 1.63; https://github.com/ledger/ledger/issues/534) and Debian Stretch (boost 1.62; https://github.com/ledger/ledger/issues/539) These issues occur only on 32-bit architectures (i386/i686), and on Fedora 26 (boost 1.63) some segmentation faults can be /fixed/ by executing: | std::ostream *dummy = new iostreams::stream<iostreams::file_descriptor_sink>(2, iostreams::never_close_handle); but this does not "work" on Debian Stretch (boost 1.62). Does that ring a bell for anyone? (NB: I don't want to im- ply that there is a bug in Boost, but maybe someone recog- nizes the scenario and can suggest where the real issues probably lie.) TIA, Tim

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Compiling boost for Intel compiler on Windows
by Boaz Barnea MTH 19 Feb '18

19 Feb '18

Hi, I followed the steps<https://software.intel.com/en-us/articles/building-boost-with-intel-c-compi…> (with adjustments for intel compiler version 18) to build boost using Intel compiler. I have Intel i7 processor, with windows 7 64-bit version, therefore I run compilervars.bat batch with intel64 flag. I run b2 with address-model=32, yet in boost libboost_log-iw-mt-gd-x32-1_66.lib is created as an x64 binary (I see it using 'dumpbin /HEADERS libboost_log-iw-mt-gd-x32-1_66.lib') I guess the library is built by default as x64 for some reason.... any idea? Thanks, Boaz. *********************************************************************************************** Please consider the environment before printing this email ! The information contained in this communication is proprietary to Israel Aerospace Industries Ltd. and/or third parties, may contain confidential or privileged information, and is intended only for the use of the intended addressee thereof. If you are not the intended addressee, please be aware that any use, disclosure, distribution and/or copying of this communication is strictly prohibited. If you receive this communication in error, please notify the sender immediately and delete it from your computer. Thank you. Visit us at: www.iai.co.il

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[Container] flat_multimap::erase crash on OSX 10.13.3/AppleClang Release mode
by Ho Cheung 19 Feb '18

19 Feb '18

Hi all, Please see attached CMakeLists and cpp file for minimal reproducible example. The throw seems to not always trigger (roughly 20-30% failure rate for me). Compiler: hoc$ clang --version Apple LLVM version 9.0.0 (clang-900.0.39.2) Target: x86_64-apple-darwin17.4.0 Thread model: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin hoc$ system_profiler SPSoftwareDataType | grep Version System Version: macOS 10.13.3 (17D47) Kernel Version: Darwin 17.4.0 -- This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.

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[boost] Yap's formal review is starting now!
by Louis Dionne via Boost 16 Feb '18

16 Feb '18

Dear Boost community, The formal review of Zach Laine's Yap library starts Monday, February 5th and ends on Wednesday, February 14th. Yap is a C++14-and-later library to build expression templates. Yap uses new features introduced in C++14/17 to make the library simpler to use and compile faster than existing solutions, such as the well known Boost.Proto library. The documentation is available here: https://tzlaine.github.io/yap/doc/html/index.html The GitHub repository is available here: https://github.com/tzlaine/yap We encourage your participation in this review. At a minimum, please state: - Whether you believe the library should be accepted into Boost - Your name - Your knowledge of the problem domain You are strongly encouraged to also provide additional information: - What is your evaluation of the library's: * Design * Implementation * Documentation * Tests * Usefulness - Did you attempt to use the library? If so: * Which compiler(s)? * What was the experience? Any problems? - How much effort did you put into your evaluation of the review? All issues discussed during this review will be tracked on the library's GitHub issue tracker at https://github.com/tzlaine/yap/issues. Regards, Louis Dionne P.S.: I've been having trouble posting to this list. If this ends up being a duplicate post, let's make this one the official one. _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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I search information about directory_iterator
by Andy 16 Feb '18

16 Feb '18

I have: #include <boost/filesystem.hpp> namespace fs=boost::filesystem; for (auto& de : fs::directory_iterator("D:\\prog\\alg\\Diff")) { fs::path p = de.path(); auto ext = fs::extension(p); } directory_iterator is object or non-objective method? How can I write something similar, but database iterator. I want get information from mySQL. The simplest way is add everything returning by select to vector of vector of string. But I prefer database iterator. How it write? How is in general directory_iterator as a iterator model?

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We need more mentors for GSoC
by David Bellot 14 Feb '18

14 Feb '18

Hi Boost community, we have already a few mentors, but we need more. If you're interested working with top-level C++ students from all around the world, please contact me and I'll add you to the list of mentors. We need more mentors now ! Best regards, David

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Boost C++ is a mentoring organization for GSoC'18 !
by David Bellot 12 Feb '18

12 Feb '18

We just received this message from Google. It says it all ! *Congratulations! Boost C++ Libraries has been selected as a Google Summer of Code 2018 mentor organization.* This year again, we will be a mentoring organization for the Google Summer of Code. If you want to be a mentor, please contact me right now and register on the Google Summer of Code website too. Best regards, David

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boost serialisation with clang 5.0.1
by avib369 . 12 Feb '18

12 Feb '18

I having a few problems with boost 1.53. I can build boost1.53 with, gcc 4.3-> 7.3, intel 15->17, clang 3.9.1 However with clang 5.0.1 , things go a bit pear shape. I can build boost 1.53/clang 5.0.1 and and my application no problem. However at runtime in crashes in release mode but works ok in debug mode. My early debugging point to serialisation of ptrs is broken in release mode (03) and clang 5.0.1 Has any one else seen this issue in later boost version with clang 5.0.1 ? ta, Avi

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(no subject)
by giridhar 12 Feb '18

12 Feb '18

Hi Boost https://goo.gl/wknrVF Giridhar

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[Graph] const safety in edge_list_impl::edge_iterator
by Hormoz Zarnani 11 Feb '18

11 Feb '18

Hello, I am wondering if there is a particular reason why the == and != operators for edge_list_impl::edge_iterator (defined in boost/graph/edge_list.hpp) are not marked const: // The implementation class for edge_list. template <class G, class EdgeIter, class T, class D> class edge_list_impl { public: ... struct edge_iterator { ... bool operator==(const self& x) { return _iter == x._iter; } bool operator!=(const self& x) { return _iter != x._iter; } EdgeIter _iter; edge_id _i; }; ... }; Also, it does not seem correct to have different const qualifiers for the operands of these operators (the above effectively says that the right operand is const, but the left operand may be changed). Thanks, Hormoz

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[Interprocess] Message queue hex names
by Davies, John 09 Feb '18

09 Feb '18

I have a handful of processes all communicating with message queues. Infrequently, if a process crashes and restarts, it can't connect to the previously created message queue and creates a new one with a long hex name. This is under Windows, but I'm seeing indications the same thing is happening under Linux. Or something very similar. Under what circumstances does it do this and if I can't stop it, can I at least detect that it happened? ________________________________ The information contained in this message may be confidential and legally protected under applicable law. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, forwarding, dissemination, or reproduction of this message is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message.

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coroutine2: pull/push_type ctors with r-value ref arg
by MM 09 Feb '18

09 Feb '18

Hello, push_type class have this ctor: template< typename Fn > push_type( Fn && fn) that moves the object fn, leaving it in a moved-from state. I have a vector V1<C> of class C instances that expose a public member operator: void operator()( coroutine::pull_type& source ); and I would like to construct a vector V2 of push_types, of same size, each element of V2 I construct by emplacing back a element from V1. I assume that leaves the objects in vector V1 in a moved-from state and not usable. Those objects C in V1 are needed for other purposes. Can I use those instances of C by accessing them where they've been moved to inside the elements of V2? If not, should I make a copy of V1 before populating V2? Thanks,

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Mailman upgrade
by Sys Admin - Boost 08 Feb '18

08 Feb '18

All, Per https://bugs.launchpad.net/mailman/+bug/1747209, Ciere staff will install 2.1.26 beginning 9-Feb-2018 04:00 UTC. While the maintenance is performed, incoming messages to the mailing lists for Boost will be temporarily blocked. This may result in “temporarily unable to deliver” messages received by senders if a message is delivered during the upgrade. The upgrade is expected to finish by 9-Feb-2018 05:00 UTC. Thanks, Brad Johnson Your Friendly Mailing List Admin

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[test] data driven test fails to compile when number of samples greater than 9
by Georgios Sermaidis 08 Feb '18

08 Feb '18

Hello, I am having trouble compiling a simple data driven test with 10 samples. I am using clang++ (Apple LLVM version 9.0.0 (clang-900.0.39.2))with C++14 flags enabled. According to this help page http://www.boost.org/doc/libs/1_66_0/libs/test/doc/html/boost_test/utf_refe… <http://www.boost.org/doc/libs/1_66_0/libs/test/doc/html/boost_test/utf_refe…> my compiler should have no problem dealing with number of samples greater than BOOST_TEST_DATASET_MAX_ARITY which is 10 by default. Even defining BOOST_TEST_DATASET_MAX_ARITY to 20 prior to including any headers still fails to compile with the following error: /usr/local/include/boost/test/data/test_case.hpp:182: error: no matching function for call to 'bind' boost::bind( &TestCase::template test_method<Arg...>, ^~~~~~~~~~~ Any ideas how to fix it? Here is the code: #define BOOST_TEST_MODULE dataset_example68 #define BOOST_TEST_DYN_LINK #include <boost/test/unit_test.hpp> #include <boost/test/data/test_case.hpp> #include <boost/test/data/monomorphic.hpp> #include <sstream> namespace bdata = boost::unit_test::data; BOOST_DATA_TEST_CASE( test1, bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ), sample1, sample2, sample3, sample4, sample5, sample6, sample7, sample8, sample9, sample10) {} Thank you!

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[log] Setting log format with string
by Dirk Van Haerenborgh 07 Feb '18

07 Feb '18

Hi, I'm trying to simply set the log format of the sinks using a string. For example from a config file or just in code. Take for instance this simple line taken from the basic_example (https://github.com/boostorg/log/blob/master/example/basic_usage/ main.cpp) logging::add_console_log(std::clog, keywords::format = "%TimeStamp%: %Message%"); Whenever I add %Timestamp% to the log format, I keep getting this error: terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_year> >' what(): Year is out of valid range: 1400..10000 I can easily reproduce this by running these examples (without modification): https://github.com/boostorg/log/blob/master/example/basic_usage/ main.cpp https://github.com/boostorg/log/blob/master/example/ settings_file/main.cpp Am I doing something wrong? I have this same behaviour on both boost1.62 and boost1.65. The former as installed from the debian package manager. The latter was manually compiled... -Dirk

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[intrusive] list compatibility with existing application-defined intrusive lists
by Rahul Ramadas 04 Feb '18

04 Feb '18

Hi all, boost::intrusive lists can be easily customized to be compatible with an existing doubly-linked intrusive list implementation, such as the one used in the linux kernel (struct list_head). Indeed, I have been able to declare and use a boost::intrusive::list of my own with custom traits that uses struct list_head as the underlying representation, enabling me to simply use .end().pointed_node() to get access to the list head and pass it to legacy C code that expects a struct list_head*. However, I can't think of a way to achieve interoperability in the opposite direction. For example, I have an existing function (to be precise, a callback that I pass to legacy C code), that accepts a struct list_head* that is expected to contain a list of elements of a certain type. I want some way to "wrap" this raw pointer in a type-safe intrusive list type that I use as naturally as a boost::intrusive::list (iteration, modification, etc.). I see no way to achieve this. The way I see it, what I need is a boost::intrusive::list_ptr, a container that doesn't actually own the list head, but rather, points to a list head stored elsewhere. It would have the same interface as a list, allowing me to push_back, clear, etc., but behaves as a pointer when it comes to moves and copies. Additionally, there should also be a boost::intrusive::const_list_ptr, which will not allow me to modify the list, but still allows iteration and other non-modifying operations. Unless, of course, there are already existing mechanisms to achieve this. If anyone has any ideas, please let me know. Thanks.

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Boost Python with Continuum Anaconda?
by Stephen Gray 02 Feb '18

02 Feb '18

I'm trying to get started with Boost Python. I've built the Boost Python libraries and linked a simple test programme with embedded Python. My Python environments are managed by Anaconda. There are errors at runtime as detailed in this Stackoverflow posting: https://stackoverflow.com/questions/48552092/boost-python-embedding-error Can anyone please help me understand what the issue is and how to solve it? With thanks.

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asio: cancelling a named pipe client
by Stian Zeljko Vrba 01 Feb '18

01 Feb '18

I have a client which connects to a named pipe as follows: CreateFile(pipeName.c_str(),GENERIC_READ | GENERIC_WRITE, 0, nullptr, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, nullptr); The result of this call is assigned to a stream_handle. I want that io service shuts down orderly by run() returning due to running out of work. To achieve this, I post a lambda that effectively calls cancel() on the handle (hidden inside Kill()): _io.post([this]() { for (auto& w : _workers) w->Kill(); }); However, cancel() has no effect: the callback for async_read continues to return with error code of zero and data read from the pipe. For reference, this is the read call with its handler: template<typename T> void read(T& ioh, const asio::mutable_buffer& buf) { ioh.async_read_some(asio::buffer(buf), [this, self = shared_from_this()](const boost::system::error_code& ec, size_t sz) { if (ec == boost::system::errc::operation_canceled) return; if (ec) QUINE_THROW(Error(self->_ownersId, ec, "async_read_some")); self->ReadCompleted(sz); }); } ReadCompleted() processes the received data and loops by calling read() again. If I call close() the callback gets an error code and everything works out correctly, *except* that I get an error code [invalid handle] that gets logged as an error (though it's not). Am I correct in assuming that cancel() is an apparent noop in this case because of the race-condition where an I/O request completes successfully before cancel is invoked? If so, can you suggest a more elegant way (i.e., a way that doesn't induce a hard error) of exiting a loop as described here? Setting a member variable instead of calling cancel? Given the existence of the race-condition, what are use-cases for cancel? How to use it correctly, if at all possible? -- Stian

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Using Boost 1.66 with VS2017
by Tim Burgess 01 Feb '18

01 Feb '18

Hi, I'm getting the following message during compilation of my application: 1>Info: Boost.Config is older than your compiler version - probably nothing bad will happen - but you may wish to look for an update Boost version. Define BOOST_CONFIG_SUPPRESS_OUTDATED_MESSAGE to suppress this message. I don't want to suppress the message, but would appreciate any mods I need to do to actually stop its cause. Many thanks in advance for any suggestions. Best wishes. Tim Burgess

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