March 2019 - Boost - lists.boost.org

CMake Announcement from Boost Steering Committee
by Jon Kalb 13 Aug '24

13 Aug '24

The libraries produced by the Boost community have had a greater impact on the way that the C++ community writes code than any other library implementation. The focus of the Boost community will always be on the libraries, but it is undeniable that we are dependent on and often limited by the infrastructure of our trade. Years ago, the move to Git was contentious; yet, it was required to improve development. In a similar vein our build system has become an impediment for many developers and users, existing and prospective. Therefore, we, the Steering Committee, announce to the Boost community our desire and intent to move Boost’s build system to CMake for users and developers alike. We are soliciting comments and proposals from the community to guide the process and the goals. Our desire is that the community can come to consensus by the end of the calendar year with a vision of supporting users and developers. We understand that the actual process of achieving the end goal will be long, time consuming, and not without its share of conflict. We also recognize that the Boost community is comprised of bright and passionate individuals that are eager to get involved and help get work done. The members of the Steering Committee have been encouraged by the discussions and activity surrounding CMake on the mailing lists over the years and know that many people have voiced visions. We hope that each of you rejoins the discussion to support this initiative and contributes to the common goal of improving Boost’s integration into the broader C++ ecosystem. For the Boost Steering Committee, Jon Kalb, Chair jonkalb(a)boost.org

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[asio][coroutine] forbid_suspend blocks
by Vinícius dos Santos Oliveira 07 Aug '19

07 Aug '19

I've implemented a dumb linter using Python + clang API that allows you to mark certain blocks as “atomic in respect to coroutines” using C++11 attributes. Usage example follows: void f() { int yield; g(yield); [[bt::forbid_suspend]] { // Comment this call to make linter accept the code g(yield); t(); } } You can change bt::forbid_suspend to another identifier by tuning settings on the beginning of the script. The prefix forbid was inspired by Rust's linters[1] as you cannot disallow the linter from inside the forbid_suspend block. Some limitations follow: - A suspend point is identified by looking references to any id equals to yield in the last argument passed to function calls. It means that yield[ignored_ec] and alike will be correctly identified, but it needs to be named yield and it needs to be the last argument to the function call. - I haven't found a way to extract attributes related to COMPOUND_STMT nodes with clang API, so I manually look for token gaps and do a simple regex. It means you cannot use macros to [[bt::forbid_suspend]] as the macro won't be expanded. - You better call the script with '-x c++' and also ' -I/usr/lib/clang/5.0.1/include'. Like I've said in the beginning of the email, it's a *dumb* linter, which means it doesn't try to handle all cases. Therefore, I don't hope to do many changes to it or maintain it to work against newer releases of clang and I'm only uploading it to gist (not fullblow Github): < https://gist.github.com/vinipsmaker2/d930fbe5b7597432b021effe618da171>. It should also be easy to hack as it is very small. I'm releasing the linter under public domain. Enjoy. I have been using fibers in a daily basis on the last months of my job to solve networking problems on a gateway project. Some of the technologies I use are: - Boost.Asio and its spawn function. - A few custom synchronization primitives for the fibers (e.g. mutex, semaphore). - Eventually I'll have to write a custom spawn function that returns a joinable handle so I can kill the usage of a fiber::barrier in a few places. I've been using the linter for about a week already and looks fine. My use case are: - To prevent iterator invalidation in regions accessing shared variables. - To guarantee events order in algorithms that handle races (cannot yield while task YYY hasn't finished). The project I use it in is not an open source project, so I cannot talk much more about it. Also, I don't claim my solution is original. I wouldn't be surprised if the very same solution exists in the wild (please let me know if you know of a similar approach). This is not a new problem. It is know for some time. For instance, in P0171, Gor Nishanov noted this same problem: “In coroutines the suspend point is clearly marked with await, which tells the reader that something unusual happens in this function and allows the reader, for example, to confirm whether the lifetimes of the objects of interest align with the lifetime of the coroutine or not, whether some locks need to be acquired to protect some concurrently accessed data, and whether some locks need to be released before the execution reaches the suspend point.” — <http://open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0171r0.html>, 2015 However, the solution he presented was to manually examine whole blocks of code without help from the compiler. I argue that the solution he presented is as error-prone as manually looking for exit paths that don't free acquired resources in languages lacking RAII. And I've been spoiled too much by RAII. Furthermore, I take this comment of his with highly suspicious look: “Since we are on the subject of maintenance nightmares, we would like to offer a conjecture that the absence of the await in P0114 is a likely source of many maintenance nightmares. Without a syntactic marker to signal to the person reading the code that something funny is going on, it is impossible to tell whether the following code is correct or not” — http://open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0171r0.html If I had to give a vote to the proposal he was defending or Chris' proposal, I'd probably have chosen Chris'. [1] https://doc.rust-lang.org/reference/attributes.html# lint-check-attributes -- Vinícius dos Santos Oliveira https://vinipsmaker.github.io/

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Non-ASCII Path Names in Repo
by Tom Kent 25 May '19

25 May '19

In the last few days we've had a non-ASCII path name added to the repo: tools/boostdep/test/utf8-test-ßµ™∃ Which came with commit 8893d1c57951a [1] I noticed this because a python 2 script (calling shutil.copytree) I had running on windows that copied the repo around started to fail. I've long needed to update that script to python 3, and am working on this. However, I wanted to point this out to the list so we could discuss if there are any other ramifications of having a non-ascii path. I vaguely remember some discussion about something like this in the past, but couldn't find it via search. If this is already a settled topic, that's great. Tom [1] https://github.com/boostorg/boostdep/commit/8893d1c57951a4a83705ed203005576…

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Re: [boost] [ Interest? ] [ out_ptr ] Tiny C++ Abstraction for C-Style Output Pointers
by Bjorn Reese 12 May '19

12 May '19

On 06/28/18 21:03, ThePhD via Boost wrote: > out_ptr is a small abstraction for making types such as > std::unique_ptr, std::shared_ptr, boost::shared_ptr, and the upcoming > std::retain_ptr > <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0468r0.html> work > work C-Style output functions as a parameter, addressing the need of > wanting to be able to do "my_c_api_init( foo, bar, &my_smart_ptr );". It's Does out_ptr have other use-cases than C interoperability?

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[thread] compiler error gcc 7.3 on cygwin
by James E. King III 06 May '19

06 May '19

Getting an internal compiler error with gcc 7.3 but only on cygwin 64-bit. Jim@pulsar /cygdrive/c/boost/libs/thread $ ../../b2 --abbreviate-paths toolset=gcc cxxstd=11 define=_POSIX_C_SOURCE=200112L define=__USE_ISOC99 threadapi=pthread address-model=64 variant=release -q ... gcc.compile.c++ ../../bin.v2/libs/thread/test/test_10963_c.test/gcc-7.3.0/rls/cxstd-11-iso/thrd-mlt/vsblt-hdn/test_10963_c.o In file included from ../../boost/thread/detail/invoker.hpp:30:0, from ../../boost/thread/future.hpp:31, from ../../libs/thread/test/test_10963.cpp:13: ../../boost/thread/detail/invoke.hpp: In function ‘decltype (*(forward<A0>)(boost::detail::invoke::a0).*boost::detail::invoke::f) boost::detail::invoke(Fp&&, A0&&) [with Fp = void (boost::executors::basic_thread_pool::*)(); A0 = boost::executors::basic_thread_pool*]’: ../../boost/thread/detail/invoke.hpp:102:43: internal compiler error: in gimplify_expr, at gimplify.c:12006 return (*boost::forward<A0>(a0)).*f; ^ Please submit a full bug report, with preprocessed source if appropriate. See <https://gcc.gnu.org/bugs/> for instructions. "g++" -std=c++11 -fvisibility-inlines-hidden -m64 -mthreads -O3 -finline-functions -Wno-inline -Wall -pedantic -fvisibility=hidden -Wextra -Wno-long-long -Wno-unused-parameter -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED -DNDEBUG -D_POSIX_C_SOURCE=200112L -D__USE_ISOC99 -I"../.." -c -o "../../bin.v2/libs/thread/test/test_10963_c.test/gcc-7.3.0/rls/cxstd-11-iso/thrd-mlt/vsblt-hdn/test_10963_c.o" "../../libs/thread/test/test_10963.cpp" ...failed gcc.compile.c++ ../../bin.v2/libs/thread/test/test_10963_c.test/gcc-7.3.0/rls/cxstd-11-iso/thrd-mlt/vsblt-hdn/test_10963_c.o... If I change the C++ language level to 03 the problem goes away. I also cannot reproduce it on linux with the same version of compiler (but it probably isn't the exact same compiler code). Should I go ahead and file that gcc bug? - Jim

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[review][variant2] Variant2 Review Starts April 1
by Michael Caisse 06 Apr '19

06 Apr '19

The Boost formal review of Peter Dimov's Variant2 library will take place April 1 - 10, 2019. Please consider participating in this review. The success of Boost is partially a result of the quality review process which is conducted by the community. You are part of the Boost community. I will be grateful to receive a review based on whatever level of effort or time you can devote. Variant2 is a never-valueless C++11/14/17 implementation of std::variant. >From the README: The class boost::variant2::variant<T...> is an almost conforming implementation of std::variant with the following differences: * A converting constructor from, e.g. variant<int, float> to variant<float, double, int> is provided as an extension; * The reverse operation, going from variant<float, double, int> to variant<int, float> is provided as the member function subset<U...>. (This operation can throw if the current state of the variant cannot be represented.) * variant<T...> is not trivial when all contained types are trivial. To avoid going into a valueless-by-exception state, this implementation falls back to using double storage unless * one of the alternatives is the type monostate, * one of the alternatives has a nonthrowing default constructor, or * all the contained types are nothrow move constructible. If the first two bullets don't hold, but the third does, the variant uses single storage, but emplace constructs a temporary and moves it into place if the construction of the object can throw. In case this is undesirable, one can force emplace into always constructing in- place by adding monostate as one of the alternatives. You can find the source code here: <https://github.com/pdimov/variant2> and the documentation here: <https://pdimov.github.io/variant2/doc/html/variant2.html> Please take an early look at the library and ask questions now. Peter Dimov is very active on the Cpplang Slack #boost channel; however, please consider using the Boost Dev or User Mail Lists so that the entire community might benefit from your conversation. Note: The repository contains an expected implementation also; however, that is not being considered in this review. Thank you for your participation! michael -- Michael Caisse Ciere Consulting ciere.com

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GSoC'19 [Boost.Geometry : Implementing algorithms for the concave hull problem]
by yaghyavardhan singh khangarot 06 Apr '19

06 Apr '19

Hi, I am interested in contributing to Boost.Geometry and would like to work on the Project 1 (Implementing algorithms for the concave hull problem) as my GsoC’19 project. I had some discussion regarding this with Adam Wulkiewicz. I have read the paper ( Moreira, Adriano J. C., and Maribel Yasmina Santos. “Concave hull: A k-nearest neighbors approach for the computation of the region occupied by a set of points.”) and currently going through the paper “A New Concave Hull Algorithm and Concaveness Measure for n-dimensional Datasets*” ( https://www.iis.sinica.edu.tw/page/jise/2012/201205_10.pdf )) . These are the papers given in the project description. I am also searching for any other algorithms (newer or better) for the concave hull problem. Please direct me to any other algorithms related to this project. Regards Yaghyavardhan

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Master branch open for merging
by Marshall Clow 03 Apr '19

03 Apr '19

The master branch is is now open for post-beta merges, but only as described in the Post-Beta Merge Policy. See < https://github.com/boostorg/boost/wiki/Releases%3A-Beta-Merge-Policy> -- The Boost Release Team

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[gsoc19] Seeking a mentor for Boost.GIL project
by Igor Antropov 02 Apr '19

02 Apr '19

DearSir/Madam, My name isIgor Antropov and I would like to participate in GSoC 2019.I amfirst-year undergraduate master majoring in Software Engineering at ITMOUniversity (Saint Petersburg National Research University of Information Technologies,Mechanics and Optics).I aminterested in computer vision and C++. I have made AR-application using Unityand OpenCVForUnity at my third-year of bachelor degree. Unfortunately, thatOpenCVForUnity was based on OpenCV version 2.1 or smaller and was the only onefree to use. There was no algorithm for markers detection, so I had to codeit. At the fourth-year, I have implementobject tracking algorithm with C++ and OpenCV using HOG features and colornames features. Additionally, I havebeen working as programmer with Qt for 1 year. I aminterested in implementation of different algorithms using GIL, so I propose toimplement some image feature detection and matching algorithms. For example,ORB keypoints detector(http://www.willowgarage.com/sites/default/files/orb_final.pdf) and brute-forcematching. Besides, I think Boost.GIL numeric algorithms can have some improvements (add 2D convolution, add convolve_option_extend_reflect as convolve_boundary_options). If Boost.GIL users need some other algorithms to be implemented,please contact me. As my competencytest, I have implement a simple Canny edge detection algorithm using GIL. https://github.com/boostorg/gil/pull/258 Sincerely, IgorAntropov

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[gsoc19] Seeking a mentor for Boost.Geometry project related to triangulation and random sampling
by Tinko Bartels 01 Apr '19

01 Apr '19

Hi, I am interested in participating in this year's Google Summer of Code with a contribution to Boost.Geometry. I am looking for mentors and I understand that potential mentors for Boost.Geometry-related projects are Vissarion Fysikopoulos and Adam Wulkiewicz. My proposal is a project that is based on project 3 and 4 for Boost.Geometry in the Wiki. I propose to add concepts for triangles, triangulation, and point-generators for random sampling, as well as corresponding models and an algorithm for Delaunay-triangulation with parametrizable geometric predicates. The first draft of my proposal can be found here: https://docs.google.com/document/d/17M44Hpn0KMuECztCbkvTYIeN2EiXbMAUsVni22K… My implementation of the tasks in the competency tests can be found here: https://tinko92.github.io/boost_geometry_GSoC_2019_project_3_4_test/ I'd be thankful for any feedback. Kind regards, Tinko Bartels -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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[format] Allow the format library to use std::optional
by Sean Farrow 30 Mar '19

30 Mar '19

Hi, Would be possible/desired to allow boost.format to use std::optional instead of boost.optional when compiling a C++17 project. I've raised a GitHub issue to resolve this: https://github.com/boostorg/format/issues/63 I would be happy to do this if it were warranted. Kind regards Sean.

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Re: [boost] [Boost-build] Building Boost 1.69 with Visual Studio 1.69
by Steven Watanabe 29 Mar '19

29 Mar '19

AMDG On 3/27/19 12:02 PM, Paul Bristow wrote: >> <snip> > I was fully up-to-date on develop yesterday, and installed git a week ago (new machine ;-) ). > The current revision of Boost.Build in develop should be e22a75c8 (March 18) > I am also slightly concerned that specifying the cl.exe fully may not be updated when Visual studio is updated, as happens today? > But it does seem to using the new compiler version, even though the full cl.exe file specification is no longer correct. > Similarly vsvarsall.bat location in the set command will change. > > But I am getting Boost library files built OK for several compilers and versions, so that's progress. > Hmm. It looks like VS2019 isn't being autodetected. It seems to be working for Tom's test runners. Maybe see what you get from: vswhere -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath -version "[16.0,17.0)" (This is how Boost.Build tries to detect VS2019.) In Christ, Steven Watanabe

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Regarding BOOST.Astronomy
by Sarthak Singhal 29 Mar '19

29 Mar '19

Hello everyone, I am not able to understand what exactly is to be done to complete the parser for FITS and I have also tried understanding the codebase but I am not getting what is the work done till now. Can you also provide some resources? Thanking you Sarthak Singhal

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[visibility][test][osx] visibility warnings with 1.70beta
by Raffi Enficiaud 28 Mar '19

28 Mar '19

Hi, I have a side project that requires boost.test and I thought it is the right time to use the beta build of 1.70. At link time for my project (in this case a simple boost.test module), I have tons of warnings like the following: ld: warning: direct access in function 'boost::unit_test::decorator::depends_on::apply(boost::unit_test::test_unit&)' from file '/Users/raffi/from-big-laptop/code/software_workshop/sw_thirdparties/osx/boost_1_70_0_b1/lib/libboost_unit_test_framework-xgcc42-mt-x64-1_70.a(decorator.o)' to global weak symbol 'boost::unit_test::basic_cstring<char const>::null_str()::null' from file '/Users/raffi/code/mpi/mpi_kmeans/build/MPI-Kmeans.build/Debug/test_mpi_kmeans.build/Objects-normal/x86_64/test_cls_and_func_impl.o' means the weak symbol cannot be overridden at runtime. This was likely caused by different translation units being compiled with different visibility settings. running Xcode 10.1 on 10.14/mojave. I am building boost like this: ./b2 \ cflags="-mmacosx-version-min=10.10" \ cxxflags="-std=c++11 -stdlib=libc++ -mmacosx-version-min=10.10" \ mflags="-mmacosx-version-min=10.10" \ mmflags="-mmacosx-version-min=10.10" \ linkflags="-stdlib=libc++ -mmacosx-version-min=10.10" \ --prefix=`pwd`/../${build_folder} \ --without-log \ --layout=versioned \ install Each of the files that are being built in my project and that are raising the warning have a compilation command like this: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -DBOOST_ALL_NO_LIB -DKMEANS_VERBOSE=0 -I/Users/raffi/code/mpi/mpi_kmeans/include -I/Users/raffi/code/mpi/mpi_kmeans/applications/include -isystem /Users/raffi/from-big-laptop/code/software_workshop/sw_thirdparties/osx/boost_1_70_0_b1/include/boost-1_70 -O3 -DNDEBUG -std=gnu++11 -o CMakeFiles/test_mpi_kmeans.dir/test/test_kmeans.cpp.o -c /Users/raffi/code/mpi/mpi_kmeans/test/test_kmeans.cpp which is pretty much what I had so far and before 1.70. Boost.test is using BOOST_SYMBOL_VISIBLE to make a symbol public, including the static build variant. Why does the linker say """ This was likely caused by different translation units being compiled with different visibility settings. """ is completely unclear to me. How can I inspect what b2 emits as compilation command line for further debugging? All those visibility issues are causing me a lot of headache :) Thanks! Raffi

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Gsod19 interest
by Damian Vicino 27 Mar '19

27 Mar '19

I'm wondering if there is interest to make boost participate in the Google season of docs. The program is similar to Google summer of code in many ways, but the outcome is production of documentation. It Details: g.co/seasonofdocs <https://developers.google.com/season-of-docs/>

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[GSOC 2019]
by shehab alaa 27 Mar '19

27 Mar '19

Hi, I’m student willing to participate in GSOC 2019. I have finished my competency test for Boost.uBLAS and I have interest in projects 2 (Adding new numerical linear and multilinear algebra algorithms).So I’m writing looking for mentor who have interest to guide me. And here is my GitHub link for competency test https://github.com/Shehabalaa/CompetencyTest Best regards, Shehab Alaa

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Re: [boost] [review][variant2] Variant2 Review Starts April 1
by dariomt＠gmail.com 26 Mar '19

26 Mar '19

> > The class boost::variant2::variant<T...> is an almost conforming > implementation of std::variant with the following differences: > I see the useful comparison to std::variant in the doc, however I'm using boost::variant extensively in my code. It would be very useful to have also a short comparison to boost::variant in the doc, as I would expect many more current users of the venerable boost::variant than of its much younger cousin std::variant. Thanks!

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Building Boost 1.69 with Visual Studio 1.69
by Trueman, Chris 26 Mar '19

26 Mar '19

Maybe I'm getting ahead of myself given the recent topic about picking a version number for the latest MSVC toolset but I'm having trouble building boost 1.69 with Visual Studio 2019 preview. I blindly assumed the toolset was 14.20 (given the directory where cl.exe is found). Letting b2 determine the version yields vc141 in the lib names. Trying to force 142 with: using msvc : 14.2 : <path to cl.exe> ; in project-config.jam yields errors about unescaped characters. Suggestions welcomed. Chris. INTELLICORP LEGAL NOTICE: This E-Mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged and confidential information. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying or other use of this message or its attachments is strictly prohibited. If you received this message in error, please notify the sender immediately by replying to this message, and then delete it.

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[fibers] Great amount of errors and warnings raising out of valgrind
by Stephan Menzel 26 Mar '19

26 Mar '19

Hello all, I was just in the process of doing vagrind runs on a server process that recently switched to an architecture using boost fibers. Specifically buffered_channel as a number of worker fibers run in a thread. The process was regularily checked with valgrind before but now I'm getting overwhelmed by the amount of messages. Uninitialized values, invalid writes and reads all across the board and all seem to come out of fibers. I see no direct mention of my code. A few samples: ==8024== Thread 1: ==8024== Conditional jump or move depends on uninitialised value(s) ==8024== at 0x454F98: unique (circular_list_algorithms.hpp:112) ==8024== by 0x454F98: empty (list.hpp:540) ==8024== by 0x454F98: boost::fibers::buffered_channel<std::function<void ()> >::close() (buffered_channel.hp ==8024== by 0x454FDB: boost::fibers::buffered_channel<std::function<void ()> >::~buffered_channel() (buffere ==8024== by 0x4376BF: operator() (unique_ptr.h:78) ==8024== Invalid read of size 8 ==8024== at 0x9C1756: boost::fibers::context::~context() (in /my_server) ==8024== by 0x9C31CF: boost::fibers::main_context::~main_context() (in /my_server) ==8024== by 0x6B0B85E: __call_tls_dtors (in /usr/lib64/libc-2.26.so) ==8024== by 0x5D49558: start_thread (in /usr/lib64/libpthread-2.26.so) ==8024== by 0x6BC92FE: clone (in /usr/lib64/libc-2.26.so) ==8024== Address 0xa6f0010 is 32 bytes inside a block of size 232 alloc'd ==8024== at 0x4C2D1DA: operator new(unsigned long) (vg_replace_malloc.c:334) and thousands more similar to this. Now, is there something about fibers that causes this as false positives (such as valgrind not knowing about fibers or coroutines) or is there an underlying problem here? This is running on AWS Linux 2, built with gcc 7.3, boost 1.69. Multithreaded release build with debug info. Nothing out of the ordinary. I am a bit concerned about this and wanted to let the list know. Can provide more output on demand. Cheers, Stephan

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Re: [boost] [review][variant2] Variant2 Review Starts April 1
by dariomt＠gmail.com 26 Mar '19

26 Mar '19

> > On Mon, 25 Mar 2019 at 17:18, dariomt--- via Boost <boost(a)lists.boost.org> > wrote: > > > ... as I would expect many more current users of the venerable > > boost::variant than of its much younger cousin std::variant. > > > > Why do you expect that and do you think that will stay that way? Well, Boost.Variant has been around so much more time than std::variant, so this seems obvious to me. For new code, maybe people will just use std::variant, but there's more old code than new code. Also, I'd say the cost of migrating from Boost.Variant to std::variant is non-zero, and the benefits are not clear (to me), so I'd expect not many people to undergo this migration. My feeling is that the library is aimed at current users of std::variant, offering a "better" pin-compatible alternative, but if I'm using Boost.Variant I believe I also should be considered a potential user. That's why I'm curious about the Boost.Variant2 review, we might get more clarity by comparing the three versions, and we may even get guidance for a migration path from Boost.Variant to Boost.Variant2. > My > personal feeling is that C++17-use is picking up at break-neck speed. For > good or for worse, although there appears to be a lot of controversy over a > (any) variant [and there are quite some quite different implementations > around], the std::variant is the one in the std, which seems to give it a > head start. Well, in my (limited) experience Boost is ubiquitous, so being in std is not that much of a head start. > In my view there can only be one objective with boost varant2, > and that is if it is decided [here] that it is (much) better than the > current std::variant, the C++20 std::variant should be/become the proposed > boost::variant2. > > degski > I wonder if code dealing explicitly with valueless_by_exception() will break if you make this change.

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Re: [boost] [review][variant2] Variant2 Review Starts April 1
by dariomt＠gmail.com 26 Mar '19

26 Mar '19

> > dariomt--- wrote: > > > The class boost::variant2::variant<T...> is an almost conforming > > > implementation of std::variant with the following differences: > > > > > > I see the useful comparison to std::variant in the doc, however I'm > using > > boost::variant extensively in my code. > > > > It would be very useful to have also a short comparison to > boost::variant > > in the doc, as I would expect many more current users of the venerable > > boost::variant than of its much younger cousin std::variant. > > The main difference is that Variant2 is a pin-compatible replacement for > std::variant, whereas Boost.Variant isn't (at least for now). So it's > easier > to switch from std::variant to Variant2 and back (depending f.ex. on > whether > std::variant is available.) > > The second most important difference would probably be the fact that > Boost.Variant may do heap allocations. > This is useful info, thanks! I understand that the main objective is to offer a "better" std::variant, but as a user of Boost.Variant wondering "Should I consider migrating to Boost.Variant2?", I would expect a section in the doc addressing this question.

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Which forum to handle issues/questions regarding libraries
by Robert Ramey 25 Mar '19

25 Mar '19

I've been studying the boost multiprecision library and I have a few questions relating to various aspects of said library. These questions are quite specific to that library and I'm not sure that they are of wider interest other than to a couple people. So I'm wondering if it would be better to post these as library issues on github or on this list or both. It used to be simple but now we have at least three places to discuss these things: slack, here and github issues for the library in question. Also sometimes some PRs can highlight differences which can get ironed out in the PR comments. Do we have a consensus as to the preferred way to select the correct forum? Robert Ramey

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Looking for a Mentor: GSoC 19: Boost.uBLAS: Linear and Multilinear...: Project 1 and 2
by forcha glen 24 Mar '19

24 Mar '19

Hello, I am interested in any of these two projects. I do not yet have a mentor. I need mentor. Regards, Glen

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Re: [boost] Master branch open for merging
by Nikita Kniazev 22 Mar '19

22 Mar '19

I would like to merge Spirit to master. The develop contains bunch of minor changes, but I important ones are: Endian namespace pollution and macros conflict fixes: https://github.com/boostorg/spirit/commit/6c258d506c2bbadccdb9f25e481984aca… https://github.com/boostorg/spirit/commit/74c0ec310a2345cb95ffb947327f69007… https://github.com/boostorg/spirit/commit/9d48b5a23197bbbcc4a3a8990c164b1cf… GCC 6/7 regression avoidance: https://github.com/boostorg/spirit/commit/8bd9b6ece40f9324a902bb0f726e785ff… The regression matrix is green for two weeks.

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[release] Boost 1.70.0 Beta 1 is now available
by Marshall Clow 22 Mar '19

22 Mar '19

[ resending with a non-empty subject line ] Boost release 1.70.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.70.0.beta1/source/> The SHA256 checksums are as follows: dbf89645e509acb2e53eac3c633834f1dec80bd8622e6e652a9741dcf0807f17 ./boost_1_70_0_b1.7z 957b984b58656a3ec00661ecad7ef82e3a094bad36e37b9e6624843237854679 ./boost_1_70_0_b1.tar.bz2 76d149c1fb9e8a5ceb3bc1e5587edc40fa79a43e8b990d877c2210f0382b9421 ./boost_1_70_0_b1.tar.gz 71e990b2c26880521fd98459b184ee172ce1c46dcf554b6eaab7776b8b6369a6 ./boost_1_70_0_b1.zip For details of what's in the release, see < https://www.boost.org/users/history/version_1_70_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

6 14

[Process] Proposed solution for posix pipes staying open
by Bills, Jason M 22 Mar '19

22 Mar '19

Hello, I'm new to Boost and looking for some help on the right process to propose patches. I'm running in an embedded Linux environment (OpenBMC) using Boost 1.69.0 and just switched a couple of std::system() calls to boost::process::system() calls. After making this change, I noticed that each time my process executed the bp::system() call, I would get an extra pipe fd in my /proc/<pid>/fd list. I did some debugging and have found a possible solution for this issue in the Boost.Process posix headers that I would like to propose. What is the right forum or process to post my patch (post it here, github pull request, etc.)? Thanks! -Jason

2 2

questions about boost multiprecision
by Robert Ramey 22 Mar '19

22 Mar '19

I'm looking more carefully at Boost Multiprecision than I have in the past and have a couple of questions: It's not clear to me how errors are handled. For example, what happens in a divide by zero? Or what happens when a result overflows. I'm aware that this will likely vary depending on whether the arguments are arbitrary precision made a runtime or a precision fixed at compile time. In any case, looking through the manual I can't find this information. Of course this package is so ambitious, that it's possible that I've missed it but in that case a pointer would be appreciated. Spending some time on this makes me appreciate what an incredibly ambitious accomplishment this is. It's really unbelievable. I would be curious how frequently various parts of the package are used. Robert Ramey

4 4

usage of auto in tutorials
by Stephan Menzel 22 Mar '19

22 Mar '19

Hello all, I was eagerly awaiting the release of the 1.70 beta, especially for outcome, which I have much use for, having lots of async functionality. While looking at the tutorial here that https://www.boost.org/doc/libs/1_70_0_beta1/libs/outcome/doc/html/index.html I notice that auto is used instead of the types. Is there a background to this? I question if this is such a good thing in tutorials. The first thing I like to know about a new lib is the types and classes it offers and auto obfuscates this. Is there any consensus in the boost community as to how and if tutorials and docs should use auto? I have concerns about this and feel it doesn't increase the otherwise great quality of documentation and tutorials for new libs. Cheers, Stephan

10 17

[test] unit test command-line handling
by Stefan Seefeld 22 Mar '19

22 Mar '19

Hello, this is a question concerning the Boost.Test framework. I'd like to pass command-line arguments to my tests, and I'm unsure of how to proceed. I have found https://www.boost.org/doc/libs/1_68_0/libs/test/doc/html/boost_test/adv_sce…, which shows how to access the command-line programmatically, but that's declared obsolete, and it's also lacking some important info, such as how I should handle the argv vector. Are there any examples that demonstrate this use case ? Specifically: * What (non-deprecated) API can I use to access command-line arguments during test initialization ? * How does my own handling of command-line arguments interact with Boost.Test's own command-line argument handling ? Thanks, Stefan -- ...ich hab' noch einen Koffer in Berlin...

3 8

[move] Bug causing issue #81 in Interprocess
by Ion Gaztañaga 21 Mar '19

21 Mar '19

Hi, Looks like a Boost.Move bug that is causing problems in Interprocess and potentially in other libraries like Container. The bug is present in the soon to be released Boost 1.70. The bug was reported by Nikita Kniazev for Interprocess: https://github.com/boostorg/interprocess/issues/81 I've committed a simple fix in the develop branch: https://github.com/boostorg/move/commit/756c964798ff1110406fab541b85267aefb… I hope the regression can cycle soon and release managers can approve the patch for Boost 1.70. Best, Ion

1 0

[GSoC 2019] Seeking guidance for Boost.uBlas (Project 4)
by livingstonegcs 21 Mar '19

21 Mar '19

Hello Boost community, I am GCS Living Stone, a Computer Science and Engineering undergraduate at National Institute of Science and Technology. I have fair amount of knowledge in Linear Algebra and skills in C++, Python programming. I have gone through Boost GSoC2019 proposal list. I found interest in Boost.uBlas Project 4: Non-negative matrix factorization implementation. I am seeking information regarding where to submit the competency test and how to begin with the project proposal as the project description has not mentioned any specific techniques. [Also I would like to bring to your notice that the Boost.Python project just mentions the project number but does not describe the projects.] Looking forward for the advice and guidance in the mentioned issue. Thanking you, GCS Living Stone -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

1 0

GSoC : Boost.Geometry: Generic Geometry Library
by Sarah Arrey 20 Mar '19

20 Mar '19

Dear Sir/Madame, My name is Sarah Arrey. I am a student in the University of Buea, Cameroon. I have written professional programs in C++. As a result of my Anglo-Saxon culture, and currently in the faculty of science, I have good knowledge in mathematics beyond that of the high school; my country is Bilingual (English and French). I am interested in applying for the following two projects: PROJECT 3: Implementation of Algorithms for Computing the Delaunay Triangulation PROJECT 4: Implementation of Algorithms for Random Point Generation I am willing to forward code for the Programming Competency Test, when applying. How do I get started? Regards, Sarah

3 2

GSoC 2019 - Boost.Geometry: Generic Geometry Library
by Indira Ngandi 20 Mar '19

20 Mar '19

Hello, I am Indira Ngandi, a Cameroonian (not an Indian). I am a student in the University of Buea, Cameroon. I have good knowledge in C/C++. I also have good knowledge in British Further Mathematics. I am interested in applying for the following two projects. I know that only one can be accorded to me. I would like to apply for two to improve my chances of having one. The projects are: PROJECT 1: Implementing Algorithms for the Concave Hull problem PROJECT 2: Implementing Support for Non-Cartesian Geometries in Convex_Hull How do I start? Regards, Indira

4 4

Regarding BOOST.Astronomy GSOC'19
by Sarthak Singhal 20 Mar '19

20 Mar '19

Hello everyone, I am Sarthak Singhal currently in my second year pursuing Computer Science and Engineering from IIT Kanpur. I have checked out the astronomy library of boost and the work done on it in previous year's GSOC. I am interested in making contributions to this library. I am proficient in C++ and have an experience of about one and a half years. But before that I want to complete the programming competency test and wanted to know that whether I have to implement the vector class from scratch or I have use the part of boost/astronomy/coordinate/cartesian_representation.hpp and some other header files.

2 1

GSoC Linear and Multilinear Algebra with Matrix and Tensor Computations
by forcha glen 19 Mar '19

19 Mar '19

Hello, I am Glen Beloa. I am a student in the University of Buea, Cameroon. I am studying for a Master's degree in Telecommunications and Networking. I understand that I can apply for two projects. I would like to apply for the projects: Project 1 : Extending and modifying boost::numeric::ublas::tensor Project 2 : Adding new numerical linear and multilinear algebra algorithms How do I get started? Regards, Glen

1 0

GSoC Linear and Multilinear Algebra with Matrix and Tensor Computations
by forcha pearl02 19 Mar '19

19 Mar '19

Hello, I am Pearl Fri. I am a student in the University of Buea, Cameroon. I am studying for a BEng degree in Computer Engineering. I would like to apply for the following two projects: Project 3 : Modifying (smart) expression templates Project 4: Implementing non-negative matrix factorization in uBlas How do I get started? Regards, Pearl

1 0

MSVC 2019 and 1.70 beta
by Olaf van der Spek 19 Mar '19

19 Mar '19

Hi, Is 2019 not properly supported yet? > Building Boost.Build engine > 'cl' is not recognized as an internal or external command, > operable program or batch file. > Failed to build Boost.Build engine. > Please consult bootstrap.log for further diagnostics. >From a dev prompt it doesn't appear to work either: ********************************************************************** ** Visual Studio 2019 Developer Command Prompt v16.0.0-pre.4.2 ** Copyright (c) 2019 Microsoft Corporation ********************************************************************** C:\Program Files (x86)\Microsoft Visual Studio\2019\Preview>cd /vc C:\vc>cd boost_1_70_0 C:\vc\boost_1_70_0>bootstrap.bat Building Boost.Build engine Generating Boost.Build configuration in project-config.jam for msvc... Bootstrapping is done. To build, run: .\b2 To generate header files, run: .\b2 headers To adjust configuration, edit 'project-config.jam'. Further information: - Command line help: .\b2 --help - Getting started guide: http://boost.org/more/getting_started/windows.html - Boost.Build documentation: http://www.boost.org/build/ C:\vc\boost_1_70_0>b2 warning: Did not find command for MSVC toolset. If you have Visual Studio 2017 installed you will need to specify the full path to the command, set VS150COMNTOOLS for your installation, or build from the 'Visual Studio Command Prompt for VS 2017'. Performing configuration checks - default address-model : none - default architecture : none Building the Boost C++ Libraries. error: No best alternative for libs/context/build/asm_sources next alternative: required properties: <abi>aapcs <address-model>32 <architecture>arm <binary-format>elf <threading>multi <toolset>clang not matched next alternative: required properties: <abi>aapcs <address-model>32 <architecture>arm <binary-format>elf <threading>multi <toolset>gcc not matched -- Olaf

7 13

I am interested to participate in BOOST GSOC2019 project
by raghuchandra kanakamedala 19 Mar '19

19 Mar '19

Hi I am Raghuchandra studying 3rd year B.Tech at IIIT Hyderabad. It would be great to contribute to Boost.GIL: generic image library.I have ideas for both the projects.I had this course Digital Image Processing also done a project "Road detection from satellite images" based on the paper attached.my implementation link to git https://github.com/savera2020/dip_project/ .I have good skills in C++ programming. so can you provide the mail id of mentor so that we can go more deeper about the project.please consider my request to contribute to project.without a doubt i will give my best. best regards Raghuchandra

2 1

GSoC 2019 preparation , BOOST.uBLAS project
by mo'men 18 Mar '19

18 Mar '19

Hi, I’m Moamen Ahmed , 4th year student at computer engineering department at Ain Shams university ,Cairo, Egypt. I have read the interesting project ideas , and I have found myself interested in BOOST.uBLAS project. Also, I have good experience in Linear Algebra , and C++ programming. I have developed c++ projects on my own and still do . I ‘m trying now to make the competency test. I 'd like to join BOOST.uBLAS project ,so kindly , help me through the process on how to enhance my opportunity to join this project . Best regards, Moamen Ahmed

2 1

Call for Submissions: International Conference on Information Society (i-Society 2019)
by International Conference on Information Society 18 Mar '19

18 Mar '19

If you are not able to see this mail, click http://r.confinfosoc.org/mk/mr/hHTtReTMggQeh5kiYnT0MxUABiXYJEhpmmVH7xlJw4VK… for Submissions: International Conference on Information Society (i-Society 2019) ********************************************************************************** International Conference on Information Society (i-Society 2019) 22-24 October, 2019 Venue: Royal Marine Hotel Dún Laoghaire, Co. Dublin, Ireland www.i-society.eu ********************************************************************************* The i-Society is a global knowledge-enriched collaborative effort that has its roots from both academia and industry. The conference covers a wide spectrum of topics that relate to information society, which includes technical and non-technical research areas. The mission of i-Society 2019 conference is to provide opportunities for collaboration of professionals and researchers to share existing and generate new knowledge in the field of information society. The conference encapsulates the concept of interdisciplinary science that studies the societal and technological dimensions of knowledge evolution in digital society. The i-Society bridges the gap between academia and industry with regards to research collaboration and awareness of current development in secure information management in the digital society. The topics in i-Society 2019 include but are not confined to the following areas: *New enabling technologies - Internet technologies - Internet of Things (IoT) - Wireless applications - Mobile Applications - Cloud and iCloud - Multimedia Applications - Protocols and Standards - Ubiquitous Computing - Virtual Reality - Human Computer Interaction - Geographic information systems - e-Manufacturing - Electronic Discovery (eDiscovery) - Software Applications - Disruptive Technology *Intelligent data management - Intelligent Agents - Intelligent Systems - Intelligent Organisations - Content Development - Data Mining - Data Management Software - e-Publishing and Digital Libraries - Information Search and Retrieval - Knowledge Management - e-Intelligence - Compliance and Recovery from Data Loss - Knowledge networks - Risk Mitigation - Cost Efficiency - Quality Assurance - Information Management - Support Litigation - Complex Investigations *Secure Technologies - Internet security - Web services and performance - Secure transactions - Cryptography - Payment systems - Secure Protocols - e-Privacy - e-Trust - e-Risk - Cyber Security Investigations and Defence - Cyber law - Forensics - Information assurance - Mobile social networks - Peer-to-peer social networks - Sensor networks and social sensing - Information Security Compliance *e-Learning - Collaborative Learning - Curriculum Content Design and Development - Delivery Systems and Environments - Educational Systems Design - e-Learning Organisational Issues - Evaluation and Assessment - Virtual Learning Environments and Issues - Web-based Learning Communities - e-Learning Tools - e-Education *e-Society - Global Trends - Social Inclusion - Intellectual Property Rights - Social Infonomics - Computer-Mediated Communication - Social and Organisational Aspects - Globalisation and developmental IT - Social Software - Smart City *e-Health - Data Security Issues - e-Health Policy and Practice - e-Healthcare Strategies and Provision - Medical Research Ethics - Patient Privacy and Confidentiality - e-Medicine *e-Governance - Democracy and the Citizen - e-Administration - Policy Issues - Virtual Communities *e-Business - Digital Economies - Knowledge economy - eProcurement - National and International Economies - e-Business Ontologies and Models - Digital Goods and Services - e-Commerce Application Fields - e-Commerce Economics - e-Commerce Services - Electronic Service Delivery - e-Marketing - Gig Economy - Online Auctions and Technologies - Virtual Organisations - Teleworking - Applied e-Business - Electronic Data Interchange (EDI) - Innovative Strategies - Business Intelligence - Information Intelligence - Forensic Accounting *e-Art - Legal Issues - Patents - Enabling technologies and tools *e-Science - Natural sciences in digital society - Biometrics - Bioinformatics - Collaborative research *Industrial developments - Trends in learning - Applied research - Cutting-edge technologies - Industrial Control Systems - Communications Compliance * Research in progress - Ongoing research from undergraduates, graduates/postgraduates and professionals SUBMISSION INSTRUCTIONS: * You can submit your extended abstract or paper online at http://www.i-society.eu/paper-submission/ or email it to papers(a)i-society.eu * You can submit your poster via email at posters(a)i-society.eu * You can submit your workshop or tutorial proposal at workshop(a)i-society.eu or tutorial(a)i-society.eu * You can submit your speaker's proposal at speakers(a)i-society.eu IMPORTANT DATES: *Abstract or Extended Abstract Submission Date: April 25, 2019 *Notification of Abstract or Extended Abstract Acceptance / Rejection: April 30, 2019 *Research Paper Submission Date: May 01, 2019 *Notification of Research Paper Acceptance / Rejection: May 15, 2019 *Camera Ready Paper Due: July 15, 2019 *Proposal for Workshops / Tutorials: May 01, 2019 *Notification of Workshop/Tutorials Acceptance / Rejection: May 05, 2019 *Poster / Demo Proposal Submission: May 01, 2019 *Notification of Poster / Demo Acceptance: May 05, 2019 *Early Bird Registration Deadline: June 01, 2019 *Late Bird Registration Deadline: July 01, 2019 *Conference Dates: October 22-24, 2019 For more details, please visit www.i-society.euIf you wish to unsubscribe from our newsletter, click http://r.confinfosoc.org/mk/un/cJt0lk_6hTiWU2mR1gcBlsWcuOzQ_Zs4QdpVvm0OQwTN…

2 1

question about GSoC 2019
by Aziz Mousa 18 Mar '19

18 Mar '19

hello there, I want to participate in boost project in the GSoC but I am confused a little bit and there is some points that I don't understand and I need some help here please * First : to be involve in this event if I don't have my own idea should I choose one project form the list like boost.GIL or boost.uBLAS as all or should choose a specific project inside one of them like project 1, or project 2 * second: if I choose project in boost.uBLAS should I be professional in machine learning? because I am still in the start of road in this field but I am work on it and will make progress as soon as possible * third : is there any thing should I do or submit before the student registration opens in GSoC website ? thanks in advance.

2 2

Networking TS + Beast, NEW Tutorials, Read this to learn std::net !!!
by Vinnie Falco 17 Mar '19

17 Mar '19

Fellow C++, Boost, and WG21 Enthusiasts, lend me your ear! I write to inform you about exciting developments in C++ networking. First, a bit of background. Networking comes in three flavors: * Networking TS <https://cplusplus.github.io/networking-ts/draft.pdf> * Boost.Asio <https://www.boost.org/doc/libs/1_69_0/doc/html/boost_asio.html> * Standalone Asio <https://github.com/chriskohlhoff/asio> These three are for the most part identical, except that Asio flavors have additional features like ssl::stream and signal_set which are not in the TS, but will very likely appear in a future update or version. We've had Asio for over a decade now, but there is a shortage of experts. Some people believe this shortage is because Asio in particular (and thus, Networking TS since they have identical interfaces) is "difficult to use." I believe it is wrong to blame Asio for this. Concurrent programs in general are hard to write. This is applicable: "Unfortunately, today's reality is that only thoughtful experts can write explicitly concurrent programs that are correct and efficient. This is because today's programming models for concurrency are subtle, intricate, and fraught with pitfalls that easily (and frequently) result in unforeseen races (i.e., program corruption) deadlocks (i.e., program lockup) and performance cliffs (e.g., priority inversion, convoying, and sometimes complete loss of parallelism and/or even worse performance than a single-threaded program). And even when a correct and efficient concurrent program is written, it takes great care to maintain — it's usually brittle and difficult to maintain correctly because current programming models set a very high bar of expertise required to reason reliably about the operation of concurrent programs, so that apparently innocuous changes to a working concurrent program can (and commonly do, in practice) render it entirely or intermittently nonworking in unintended and unexpected ways. Because getting it right and keeping it right is so difficult, at many major software companies there is a veritable priesthood of gurus who write and maintain the core concurrent code." - Herb Sutter, "The Trouble with Locks", <http://www.drdobbs.com/cpp/the-trouble-with-locks/184401930> Although this was written in 2005 it is still relevant today. It is understandable that Asio will be the first target of anger and frustration when writing concurrent programs, since it is on the "front line" so to speak. There has also been a distinct shortage of *good* tutorials and examples for Asio. Articles or blog posts which teach you step by step, explaining everything, and giving example code which demonstrates best practices. Boost.Beast is my low-level HTTP/WebSocket library which builds on Boost.Asio: <https://github.com/boostorg/beast> In the original release of Beast, the documentation stated "prior understanding of Boost.Asio is required." However, field experience has shown that users ignore that requirement and attempt to write complex, concurrent programs as their first-time introduction to both Beast and Asio. Based on feedback from committee members, and to serve users better, the scope of Beast has been enlarged to include first-time users of networking. The upcoming Boost 1.70 release reflects this new scope and I am excited to announce some very nice things which you can access today. First of all, Beast documentation and examples no longer use the "boost::asio" namespace, they the namespace alias "net::". While this is cosmetic, it reinforces the notion when inspecting code that it is equally applicable to Boost.Asio, Asio, and Networking TS (identifiers which are not in the TS, such as signal_set, are still qualified with boost::asio). A new documentation page explains the three flavors of networking: <https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/using_io.ht…> This is also explained in my 2018 CppCon presentation: <https://youtu.be/7FQwAjELMek?t=444> I have added a "Networking Refresher", a complete overview of networking from soup to nuts. No prior knowledge or understanding of networking is required, everything is explained in detail so if you want to learn this is the place to start. I also kept it short, but it is loaded with hyperlinks for further learning: <https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/using_io/as…> There was a recent paper in Kona, P1269R0 ("Three Years with the Networking TS") about difficulty of implementing timeouts. To address this, Beast now has a stream class which implements configurable timeouts for you, and callers no longer have to fiddle with timers manually anymore. Everything "Just Works." It achieves the P1269R0 author's goal of having timeouts "built-in to asynchronous operations", but in a way that fits in with the design of the TS: <https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/using_io/ti…> I feel that this `beast::basic_stream` serves as an existence proof that the current design of Networking TS is sound - the TS offers a flexible toolbox which lets you build your own framework the way that you want it, without making odd choices for you. We are still discovering ways of leveraging it to maximum use. The beast::websocket::stream also has built-in timeouts, but they are enhanced to support "idle pings" (keeping client connections alive) and everything is fully configurable: <https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/using_webso…> All you need to do to get sensible, suggested websocket timeouts is add one line of code after creating your stream: ws.set_option(websocket::stream_base::timeout::suggested( beast::role_type::server)); To address the cumbersome boilerplate of writing composed operations (specifically the need to propagate the associated allocator and associated executor, and to avoid invoking the completion handler from within the initiating function when the operation would complete immediately) Beast adds two new utility base classes, with plentiful documentation and examples throughout: <https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/using_io/wr…> There are two well-rounded examples which show you step by step how to write these things in a safe way: <https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/using_io/wr…> <https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/using_io/wr…> I have a big, new open source project which implements a server, that uses the `system_context`, taking full advantage of native Windows and Mac OS system-level execution context features. To support this use case and industry feedback, the examples in Beast now default to being always thread-safe. All examples use a "strand", and leverage P1322R0 ("Networking TS enhancement to enable custom I/O executors"). Yes, this paper which was approved in Kona, is now implemented in both Boost.Beast, and Boost.Asio, including all of the Beast examples, so if you pick up Boost 1.70 (or the master branches from github) you can start playing with this as soon as you're done reading this message!! <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1322r0.html> We have an active #beast channel in the C++ Slack (https://slack.cpp.al) where experienced users can help, no question is too small! I hope you will join me and the rest of the Beast and Asio community in exploring what the very powerful Networking TS and Asio libraries have to offer, and build something great together! Regards P.S. Don't forget to star the repository! <https://github.com/boostorg/beast>

4 7

I am interested to participate in BOOST GSOC2019 project
by raghuchandra kanakamedala 17 Mar '19

17 Mar '19

I am raghuchandra studying 3rd year B.Tech at IIIT Hyderabad.It would be great to contribute to Boost.GIL: generic image library.I have ideas for both the projects.I had this course Digital Image Processing also done a project "Road detection from satellite images" based the paper attached.my implementation link on git https://github.com/savera2020/dip_project/.I have good skills in C++ programming. so can you provide the mail id of mentor so that we can go more deeper about the project.please consider my request to contribute to project.without a doubt i will give my best. Thanking You.

1 0

How should I teach a C++ college class?
by Joshua Marshall 17 Mar '19

17 Mar '19

I need some general input here. I'd like to pitch and run a semester long C++ course to students who have at least 1 year of programming experience. I'd like to have this open to open ended input. The biggest technical restrictions are that the University systems are running RHEL 7.4 (7.5?) with software collections devtoolset-8.

3 3

Re: [boost] [Boost-users] Networking TS + Beast, NEW Tutorials, Read this to learn std::net !!!
by Vinnie Falco 15 Mar '19

15 Mar '19

On Fri, Mar 15, 2019 at 7:38 AM Stian Zeljko Vrba <vrba(a)quine.no> wrote: > I have an idea of how to accomplish the same in C++, and > it's not pleasant -- worker thread, promise/future, blocking > queue and CancelSynchronousIO. Cannot even use > std::async because CancelSynchronousIO needs a > target thread ID. Yes, yes! I see now...your ideas on how to implement it in C++ convince me more than anything that the documentation is the problem. There's no need for any of that stuff, the code you provided could be implemented in C++ using asio without too much fuss, and there are actually several ways to do it all of which are succinct and will work wonderfully.

1 0

Re: [boost] [Boost-users] Networking TS + Beast, NEW Tutorials, Read this to learn std::net !!!
by Vinnie Falco 15 Mar '19

15 Mar '19

On Fri, Mar 15, 2019 at 7:19 AM Stian Zeljko Vrba <vrba(a)quine.no> wrote: > > I believe it is wrong to blame Asio for this. > > I disagree. Recently, I've been coding parallel, including networked & > asynchronous, programs in C# and Java, and the experience has been a JOY. You > get threads, executors, synchronization primitives, tasks, cancellation, > monadic futures and concurrent (blocking and non-blocking) data structures > out of the box with the platform, plus a myriad of extensions as libraries. > As for executors, you don't need to be bothered with them unless you really > want to for some reason. > If you were to compare POSIX or BSD sockets to C# and Java, you would say exactly the same things. Asio (like Beast) is a low-level, portable abstraction of I/O. You can BUILD "threads", "executors", "synchronization primitives", "tasks", "cancellation", "monadic futures", and "concurrent data structures" with it. Does this mean OS-level sockets are the wrong abstraction? Of course not. The reason C# seems "ahead" of C++ is two-fold: 1. WG21 goofed up by delaying networking 2. C# is not developed through the International Standards Process These mistakes are being fixed though, and you will see library support in C++ catch up by leaps and bounds. And when we finally get these things (built on top of Asio/Networking TS, which has proven over and over to be the correct low-level abstraction) it will be better than C#, Java, or Rust. Compare the documentation for Vertx (vertx.io) or netty (both Java toolkits > for writing asynchronous reactive programs) with that of asio. > Yes I agree, there is a lack of documentation and especially tutorials for beginners (which I am trying to fix). This has nothing to do with whether Asio is the right portable, low-level abstraction (it is) but the lack of guidance from the author could lead you to believe incorrect things about the lib. Once I attempted to write an asio service, tried to understand the simple > example from the documentation, and I gave up. I used a thread, blocking > call and CancelSynchronousIO (and I consider myself fortunate to develop > for Windows only that has it). > The documentation on services is particularly scant. There is no explanation of what they are for, how to use them, best practices, or even "Frequently Asked Questions." I was able to figure it out though, but I am able to focus all of my time on it. > Asio _is_ a relatively nice wrapper around socket and serial port APIs, > but that's about it > Yes now you're getting close to an accurate description. More correct would be to say that Asio provides robust abstractions of buffers, dynamic buffers, synchronous I/O, and asynchronous I/O. Networking is a subset of that (but not the only part, see signals and serial ports, and soon file I/O). > IMO. On the other hand, I could have written the same wrappers around > native APIs in two days and not haul along what I consider the baggage of > technical debt that is asio in the codebase. > There is no API technical debt. That is to say, that the interfaces are modern and up-to-date. You could argue that particular implementations such as Boost.Asio have extra code to provide C++03 compatibility, but this has nothing to do with the soundness of the design. As these interfaces are part of a TS, there will be implementations in gcc and clang appearing shortly (if not already so). These will be written from scratch so there will be no support for older C++. > Conclusion, if any: many people just want/need thread per client and > synchronous IO for simplicity, but until asio/networking TS provide for > timeouts and cancellation of synchronous requests, it's a wrong tool for > those people, me included. > If you define struct sync_socket { net::io_context ioc_; net::ip::tcp::socket_; net::steady_timer timer_; ... template<class Buffers> std::size_t write_some (Buffers const& b); }; You can easily implement timeouts in `write_some` thusly: template<class Buffers> std::size_t sync_socket:: write_some (Buffers const& b, error_code& ec) { std::size_t n; timer_.expires_after(seconds(30)); timer_.async_wait( [&](error_code ec) { socket_.cancel(ec): }); socket_.async_write_some(b, [&](error_code ec_, std::size_t n_) { ec = ec_; n = n_; }); ioc_.run(); return n; } Now, you can use `sync_socket` with all the usual sync write operations like `net::write`, and get timeouts. Thanks

1 0

Re: [boost] [Boost-users] Networking TS + Beast, NEW Tutorials, Read this to learn std::net !!!
by Vinnie Falco 15 Mar '19

15 Mar '19

On Fri, Mar 15, 2019 at 2:45 AM Cristian Morales Vega <cristian(a)samknows.com> wrote: > I have not used the synchronous API at all. But section 3.1 of P1269R0 > seems to make a good point about the lack of timeouts in synchronous > calls, doesn't it? > beast::basic_stream makes using timeouts in the async API way simpler, > but is the sync API really basically unusable because of the lack of > timeouts thing? Synchronous APIs are perfectly fine. Asio defines SyncReadStream and SyncWriteStream named requirements, allowing for generic algorithms to be implemented. Not everything is a socket (for example, a serial port). A synchronous stream represents the reliable, in-order delivery of bytes using functions that block, nothing more and nothing less. For example, serial file I/O can be represented using a synchronous stream. If the synchronous stream requirements mandated timeouts, it would eliminate a broad set of implementations (including sockets on some platforms).

1 0

Status of Disjoint Sets ?
by Brian Kuhl 15 Mar '19

15 Mar '19

Disjoint Sets is in the last few releases, has it's own test suite and github archive, but isn't mentioned on the documentation page? An oversight, or intentional? https://www.boost.org/doc/libs/1_69_0/ I see a defect that says it should move into Graph, is that part of the puzzle? https://github.com/boostorg/disjoint_sets/issues Brian

2 1

Networking TS + Beast, NEW Tutorials, Read this to learn std::net !!!
by Mike 15 Mar '19

15 Mar '19

> All in all nice intro, unfortunately it requires users to understand > templates quite well, but honestly not sure if it is avoidable, with a > gazillion customization points in ASIO. Anyone aware of a wrapper library around ASIO that doesn't offer all those customization points and maybe not the full functionality/ efficiency but is easier to use? Am 15.03.19, 01:09, Ivan Matek via Boost <boost(a)lists.boost.org> schrieb: Here are comments from somebody who "knows C++" but does not know a lot about NW and has read only the 1st <[1]https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/ using_io/asio_refresher.html> page. // get iterators representing the range of characters in the buffer auto begin = range::begin(buffer.data()); auto end = range::end(buffer.data()); Quite a weird pattern, where buffer does not have member begin, end. Maybe a sentence or two describing the rationale and complexity would be nice. I know it is O(1), but it is weird that begin/end are called on pointer. std::size_t read_lineI am tired, but is this function O(n^2)? cb += bytes_transferred; // adjust the pointer and sizeI would maybe switch to write instead of write_some to keep the code shorter, and mention write_some as another option in text. [](error_code ec, std::size_t bytes_transferred) For learning purposes I would capture something in lambda by value and note that reference capture would be buggy. using type = std::allocator<void>; Personal preference: not a fan of typedefs for relatively short types used once. All in all nice intro, unfortunately it requires users to understand templates quite well, but honestly not sure if it is avoidable, with a gazillion customization points in ASIO. _______________________________________________ Unsubscribe & other changes: [2]http://lists.boost.org/mailman/listinfo.cgi/boost References 1. https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/using_io/as… 2. http://lists.boost.org/mailman/listinfo.cgi/boost

1 0

Coordinating Boost Releases with compiler releases
by Marshall Clow 14 Mar '19

14 Mar '19

In the thread "MSVC 2019 and 1.70 beta", there has been a discussion about what to do about support for MSVC 2019, which is due to be released right about the same time that Boost 1.70. One person suggested that we delay the boost release until after the MSVC release (I think the suggestion was "May"). This general question has been discussed before (several times), since tools get released fairly often - and so does Boost. In general, I am not in favor of delaying boost releases in order to add support for 'about to be released' development tools. There are two main reasons for this: * There's always another compiler / tool about to be released. Clang 8 is imminent - currently at RC5. GCC 9.1 is scheduled to be released in early May. * Boost releases happen every four months. August is not really that far off. People who want support for tool XXXX can use "the trunk", getting it either from git or from bintray. [ Everyone knows about the tarballs at bintray, right? https://dl.bintray.com/boostorg/master/ ] Also, if we were to delay the boost release until May, then what would happen to the August release? The release process for 1.71.0 is scheduled to start at the end of June. -- Marshall

5 7

[filesystems]
by Florian Lindner 14 Mar '19

14 Mar '19

Hello, I have this innocent piece of code: namespace fs = boost::filesystem; auto path = getFilename(); // returns a string fs::create_directories(fs::path(path).parent_path()); std::ofstream ofs(path + "~"); ofs << info; ofs.close(); fs::rename(path + "~", path); which causes the exception: boost::filesystem::rename: No such file or directory: "../9f/061b4f7a5e529c964659226eedd4e5~", "../9f/061b4f7a5e529c964659226eedd4e5" However, I have no idea how that could happen. I use the rename, so that a reading process never sees an empty file, but only no file or filed with info. Is there any race involved between ofs.close() and fs:rename()? The code was executed on a distributed network filesystem (lustre). Any ideas anyone? Thanks, Florian

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Re: [boost] [Boost-users] Networking TS + Beast, NEW Tutorials, Read this to learn std::net !!!
by Vinnie Falco 14 Mar '19

14 Mar '19

On Thu, Mar 14, 2019 at 10:50 AM james <dirtydroog(a)gmail.com> wrote: > This is excellent news. Timeouts are ASIO's biggest downfall. I'll definitely check it out. > If it's low level, and performant enough, then it paves the way for ASIO-ed connectors for things like Redis and ZeroMQ. Thanks! And we are very happy to answer questions, feel free to open an issue or come to the #beast Slack channel. Regards

1 0

Cannot serialize pointer through base without void_cast_register and register_type.
by Nicolas Guillot 14 Mar '19

14 Mar '19

Hello. *** CONTEXT *** I use your serialization library since several years on linux (gcc). Now, I'm moving to windows (_MSC_VER == 1600) (boost 1.55, but same issues on boost 1.69). For my example, I use a class A in a DLL, another class B inheriting from A in its DLL and an exe, linked to those DLLs, which serializes a B object, through its A base. _______ | A | ------- /_\ | | _______ | B | ------- I make a class serializable like that (I summurize on purpose (no #include, ...)). For A it's the same thing, but it has no base class. ----> B.h ---------------------------------------- #ifdef B_EXPORTS #define B_DLL __declspec(dllexport) #else #define B_DLL __declspec(dllimport) #endif class B_DLL B: public A { public: B(); virtual ~B(); private: friend class boost::serialization::access; template <class Archive> void serialize(Archive & ar, const unsigned int version); int i; }; BOOST_CLASS_EXPORT_KEY(B) ----> B.cpp ---------------------------------------- B::B() : i(123) {} B::~B() {} template <class Archive> void B::serialize(Archive & ar, const unsigned int) { ar & SERIALIZE_BASE(ClassA); ar & SERIALIZE(i); } #define FULL_SCOPED_SERIALIZABLE_CLASS B #include "Common/InstanciateSerializationTemplate.h" ----> InstanciateSerializationTemplate.h ---------------------------------------- This file purpose is to instanciate the template B::serialize methods for each archive type, and to register the class. Here is its contents (once again, no namesapce nor include to make it easier to read): // explicit instantiate code for all archive types expected to be use: // MUST COME BEFORE BOOST_CLASS_EXPORT_IMPLEMENT // binary: template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<binary_iarchive>(binary_iarchive & ar, const unsigned int version); template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<binary_oarchive>(binary_oarchive & ar, const unsigned int version); // XML: template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<xml_iarchive>(xml_iarchive & ar, const unsigned int version); template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<xml_oarchive>(xml_oarchive & ar, const unsigned int version); // TXT: template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<text_iarchive>(text_iarchive & ar, const unsigned int version); template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<text_oarchive>(text_oarchive & ar, const unsigned int version); BOOST_CLASS_EXPORT_IMPLEMENT(FULL_SCOPED_SERIALIZABLE_CLASS) *** MY ISSUE *** All that stuff works in linux, gcc, but not in Windows. If I write in my exe this serialization code: std::ofstream ofs; ofs.open("D:\\TestSerial.xml"); boost::archive::xml_oarchive ar(ofs); shared_ptr<B> b = shared_ptr<B>(new B()); shared_ptr<A> a = b; try { ar << SERIALIZE(a); } catch (boost::archive::archive_exception& ex) { std::cout << "Serialization to stream error, what: " << ex.what() << std::endl; } catch (...) { std::cout << "Catch ... Serialization to stream error" << std::endl; } ofs.close(); With this code, I have an archive_exception: "unregistered class - derived class not registered or exported". I have to write the serialization like that: ar.register_type(static_cast<B*>(0)); boost::serialization::void_cast_register(static_cast<B*>(0), static_cast<A*>(0)); ar << SERIALIZE(a); *** QUESTION *** At least, my question: I cannot do like that: what I would like to achieve: when a new class is made serializable like above, I expect the class to be registered automatically (probabley with BOOST_CLASS_EXPORT_IMPLEMENT in InstanciateSerializationTemplate.h). It's too painfull to write the register_type and void_cast_register each time I want to serialize. What am I missing? Thank you very much for any help or recommandations. Nico

1 1

Re: [boost] MSVC 2019 and 1.70 beta
by Peter Dimov 14 Mar '19

14 Mar '19

> Tom Kent wrote: > > > Build support for VS 2019 RC (msvc-14.2) is on develop in boost build. > > Do we want to merge that to master for the release? > > I think we do. 1.70 and 2019 will release at about the same time. In fact looking at the calendar, 2019 will release (Apr 2) just before 1.70 is closed for release (Apr 3.)

3 3

boost-install-ing zlib (Was: Re: [Release] Boost 1.70.0 Beta 1 Release Candidate 2)
by Peter Dimov 13 Mar '19

13 Mar '19

> I'll need to try and see what happens with <source> in user-config. > Probably nothing good, because one would expect neither <build-name> nor > <tag> to be specified in such a case. If I remove the check for ZLIB_SOURCE, and just do alias boost_zlib : /zlib//zlib ; libraries-to-install += boost_zlib ; unconditionally in libs/iostreams/build/Jamfile, this is what happens: - when `using zlib : : <source>C:/Projects/zlib-1.2.11 ;` is in user-config, the default `b2 install` fails because `address-model=32,64 variant=debug,release` conflict as all try to build `libz.lib`. When address-model=32 variant=debug is given, `libz.lib` is installed in C:\Boost\lib, and the CMake configuration for boost_zlib correctly points to it. - when using a prebuilt `using zlib : : <include>C:/Projects/include <search>C:/Projects/lib <name>zlib-8 ;`, the CMake configuration file for boost_zlib points to "${_BOOST_LIBDIR}/zlib-8", which is not correct.

2 2

(no subject)
by Marshall Clow 13 Mar '19

13 Mar '19

Boost release 1.70.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.70.0.beta1/source/> The SHA256 checksums are as follows: dbf89645e509acb2e53eac3c633834f1dec80bd8622e6e652a9741dcf0807f17 ./boost_1_70_0_b1.7z 957b984b58656a3ec00661ecad7ef82e3a094bad36e37b9e6624843237854679 ./boost_1_70_0_b1.tar.bz2 76d149c1fb9e8a5ceb3bc1e5587edc40fa79a43e8b990d877c2210f0382b9421 ./boost_1_70_0_b1.tar.gz 71e990b2c26880521fd98459b184ee172ce1c46dcf554b6eaab7776b8b6369a6 ./boost_1_70_0_b1.zip For details of what's in the release, see < https://www.boost.org/users/history/version_1_70_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

2 3

[rational] permission to merge cmake change?
by James E. King III 13 Mar '19

13 Mar '19

Before 1.70.0 beta started, some cmake changes from Mike Dev were merged into rational. There was a typo in one of the cmake options (BOOST_RATIONA_INCLUDE_TESTS). This does not affect code nor the boost build system. Would it be okay to merge this now or should I wait? https://github.com/boostorg/rational/pull/35 Thanks. - Jim

1 1

[release] Boost 1.70.0 Beta 1 Release Candidate 3
by Marshall Clow 12 Mar '19

12 Mar '19

A new release candidates for the first 1.70.0 beta release are now available at: https://dl.bintray.com/boostorg/beta/1.70.0.beta1.rc3/source/ Changes since RC2: * Relative paths for --prefix, --libdir, etc. are now bound relative to the current working directory, instead of being relative to the Jamfile. Thanks to Tom Kent for the report, and Steven and Peter for the fixes. Changes since RC1: * The Jamfile for Boost.Predef has been updated to allow running the tests from /status. Thanks to mike.dev(a)gmx.de for the report, and to Rene for the fix. The release notes are not yet available. The SHA256 checksums are as follows: dbf89645e509acb2e53eac3c633834f1dec80bd8622e6e652a9741dcf0807f17 ./boost_1_70_0_b1_rc3.7z 957b984b58656a3ec00661ecad7ef82e3a094bad36e37b9e6624843237854679 ./boost_1_70_0_b1_rc3.tar.bz2 76d149c1fb9e8a5ceb3bc1e5587edc40fa79a43e8b990d877c2210f0382b9421 ./boost_1_70_0_b1_rc3.tar.gz 71e990b2c26880521fd98459b184ee172ce1c46dcf554b6eaab7776b8b6369a6 ./boost_1_70_0_b1_rc3.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

5 8

[Release] Boost 1.70.0 Beta 1 Release Candidate 2
by Marshall Clow 12 Mar '19

12 Mar '19

A new release candidates for the first 1.70.0 beta release are now available at: https://dl.bintray.com/boostorg/beta/1.70.0.beta1.rc2/source/ Changes since the last RC: * The Jamfile for Boost.Predef has been updated to allow running the tests from /status. Thanks to mike.dev(a)gmx.de for the report, and to Rene for the fix. The release notes are not yet available. The SHA256 checksums are as follows: 26dba8156ad08041c6da52c84a2654aefda292180afe3546a9a74dda0dfb3781 ./boost_1_70_0_b1_rc2.7z ee794d98429bc2bfae054f2fab6fde53ea95f7c5967d8b267e57c894a4d46e57 ./boost_1_70_0_b1_rc2.tar.bz2 bca5f189d87b26ab903838dee2fd4c54e9043bd35d27b8923cdef42651ae7261 ./boost_1_70_0_b1_rc2.tar.gz 6c8f3af4e64d3a04a3d3a5e98499d2f6bb460ad82c1f33ff7da800b5ab182b0b ./boost_1_70_0_b1_rc2.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

4 25

Re: [boost] [Boost-users] [release] Boost 1.70.0 Beta 1 Release Candidate 1
by Tom Kent 11 Mar '19

11 Mar '19

On Fri, Mar 8, 2019 at 9:44 PM Tom Kent <lists(a)teeks99.com> wrote: > > > On Fri, Mar 8, 2019 at 8:57 PM Tom Kent <lists(a)teeks99.com> wrote: > >> >> >> On Fri, Mar 8, 2019 at 6:42 PM Marshall Clow via Boost-users < >> boost-users(a)lists.boost.org> wrote: >> >>> On Fri, Mar 8, 2019 at 10:21 AM Marshall Clow <mclow.lists(a)gmail.com> >>> wrote: >>> >>>> The release candidates for the first 1.70.0 beta release are now >>>> available at: >>>> >>>> https://dl.bintray.com/boostorg/beta/1.70.0.beta.1.rc1/source/ >>>> >>>> The release notes are not yet available. >>>> >>>> The SHA256 checksums are as follows: >>>> >>>> a7c570d6307d05dc8d45a3b4c69a0afdcba2b22eac0c4da4d496559f53db7b89 >>>> ./boost_1_70_0_b1_rc1.7z >>>> 4b91b9a203cf12f6001cf39de83c7cc005fbc5390e2b4b2fc29ce7b19c0537a7 >>>> ./boost_1_70_0_b1_rc1.tar.bz2 >>>> 460dd6499bba9df04c6bfa219b26097bad803b8758304ba45f2fc291aa42c96e >>>> ./boost_1_70_0_b1_rc1.tar.gz >>>> f209c9a086ed2c7882a0bc8755792f436eb141eaeb8c823ed57295ca9ce25b93 >>>> ./boost_1_70_0_b1_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. >>>> >>> >>> >> I'm having a problem with B2 in this release. >> >> For many releases now, I have run a command such as: >> b2 -j16 --build-type=complete toolset=msvc-10.0 address-model=64 >> architecture=x86 --prefix="./" --libdir=lib32-msvc-10.0 >> --includedir=temp_inc install >> >> to get the windows builds of each toolset. For the install, I set the >> prefix as the current directory, so that I'll get a lib{arch}-msvc-{ver} >> directory for each toolset in there. However, with this 1.70 release, it >> seems to ignore my prefix and put the headers in >> libs/headers/build/temp_inc/boost-1_70/boost, instead of >> temp_inc/boost-1_70/boost. For the libraries, it scattered them throughout >> the build in directories such as libs/coroutine/build/lib32-msvc-10.0/. >> >> Any thoughts on what might be causing this? Am I using the --prefix >> --libdir and --inlcudedir correctly? Or at least not badly enough to >> warrant this? >> > > Also, even though I have BZIP2_SOURCE and ZLIB_SOURCE set, I'm not seeing > the appropriate bzip2 and zlib libraries being generated. > > After updating my scripts to us "staging" instead of "install" to avoid the above issue, I was able to get everything else to build successfully for Visual Studio (msvc-10.0 through msvc-14.1, note this is the first release I haven't built against msvc-8.0 and 9.0). The only exception being the lack of bzip2 and zlib support mentioned above. toolset arch compile Link Execute msvc-10.0 32 X X X msvc-10.0 64 X X X msvc-11.0 32 X X X msvc-11.0 64 X X X msvc-12.0 32 X X X msvc-12.0 64 X X X msvc-14.0 32 X X X msvc-14.0 64 X X X msvc-14.1 32 X X X msvc-14.1 64 X X X Compile means that the b2 command completed without errors Link means that visual studio was able to link a sample executable to a library (libboost_thread-vcXXX-mt[-gd]-1_XX.lib) generated Execute means that the linked program executed without errors. Full build logs can be found at https://gist.github.com/teeks99/0aeed77c9251ba02090d9ab7372e2c73 Tom

4 4

Regarding GSoc 2019
by karmanya grover 11 Mar '19

11 Mar '19

Sir/Madam, I am a Google Summer of Code 2019 aspirant. This email is regarding inquiry of possible projects that I am interested in. Please provide the specifics for following questions. In Boost.uBLAS library, I want to know if there's some work done for python integration previously or not. I also want to inquire about Boost Astronomy library. Looking into git repository, I found that this library is fairly new. What are the aspects hoped to be achieved for this library as a full efficient and mathematical friendly. I have always been interested in Astrophysics and applying those concepts in problem solving. Apart from that, What were the previous works done in Boost.Real library by past GSoc'ers. with regards, Yours sincerely, Karmanya Grover (B.E). NSUT

3 2

[release] 1.70 Windows binaries
by Sean Farrow 10 Mar '19

10 Mar '19

Hi, I know there is a discussion regarding building 1.70 with zlib in another thread, but wondered whether there are any binaries available for msvc without zlib for the 1.70 beta rc1/2? Kind regards Sean.

1 0

[variant2] documentation request
by Andrzej Krzemienski 10 Mar '19

10 Mar '19

Hi Peter, Given that the never-empty guarantee appears to be at the heart of the motivation for boost::variant2, I would suggest to: 1. put in the documentation some motivation behind pursuing the never-empty guarantee. 2. Make it clear that never-empty guarantee is not a strong exception-safety guarantee. 3. Describe the algorithm for achieving the guarantee. The current description does not seem to cover all interesting cases, and I found the behavior quite surprising. For instance, the variant's move assignment will sometimes use T's move assignment rather than move constructor when changing the variant's type, as in the following example: https://wandbox.org/permlink/GDRyS54bpdLP7GVa Regards, Andrzej

10 32

[gsoc19] Seeking Guidance along with mentor for Boost.GIL Project
by Keshav Gupta 10 Mar '19

10 Mar '19

Respected Sir, I am Keshav Gupta currently doing my B.E. in Computer Engineering from Thapar University, Patiala, Punjab, India. Actually I want to participate in GSOC19 and want to work with you during that period. Actually I am interested in implementing various Image Processing algorithms using BOOST.GIL. and I think that I can perfectly work upon this as I am also currently doing my research in the area of Fingerprint Matching and you absolutely know that this definitely includes the usage of image processing algorithms and that why I am interested for this as I know I have the proper knowledge of C++ along with image processing algorithms. Kindly guide me how to proceed further so as to increase my chances of getting being selected in GSOC19. Also please tell me any other way how to contact the mentor of this project as I have mailed him certain number of times but didn't get any response. Waiting for your reply Regards Keshav Gupta

2 1

Re: [boost] [Release] Boost 1.70.0 Beta 1 Release Candidate 2
by Peter Dimov 09 Mar '19

09 Mar '19

> Tom Kent wrote: > > > * Can't create libraries for bzip2 and zlib (showstopper? anyone else > > seeing this?) > > I haven't seen your initial report of this issue (on the users list?) but > it's probably caused by this change: > > https://github.com/boostorg/build/commit/5ad92cd76ff393792f30aa50688c95eff2… Or maybe not. This is in 1.69.0, so it can't be the cause.

1 0

[release] Boost 1.70.0 Beta 1 Release Candidate 1
by Marshall Clow 09 Mar '19

09 Mar '19

The release candidates for the first 1.70.0 beta release are now available at: https://dl.bintray.com/boostorg/beta/1.70.0.beta.1.rc1/source/ The release notes are not yet available. The SHA256 checksums are as follows: a7c570d6307d05dc8d45a3b4c69a0afdcba2b22eac0c4da4d496559f53db7b89 ./boost_1_70_0_b1_rc1.7z 4b91b9a203cf12f6001cf39de83c7cc005fbc5390e2b4b2fc29ce7b19c0537a7 ./boost_1_70_0_b1_rc1.tar.bz2 460dd6499bba9df04c6bfa219b26097bad803b8758304ba45f2fc291aa42c96e ./boost_1_70_0_b1_rc1.tar.gz f209c9a086ed2c7882a0bc8755792f436eb141eaeb8c823ed57295ca9ce25b93 ./boost_1_70_0_b1_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

4 9

Interest in GSoC Project
by Kanav Gupta 09 Mar '19

09 Mar '19

Hello, I am third-year undergrad research student at International Institute of Information Technology, Hyderabad. I would like to contribute to Boost.GIL as a part of GSoC '19. I am currently working on a research project involving image processing and have also worked on various projects involving C++ so I guess I am competent for the project. Can you please guide me on how should I proceed? Thanks and Regards, Kanav Gupta

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[release] 1.70.0 closed for major changes
by Marshall Clow 07 Mar '19

07 Mar '19

The master branch is now closed for new libraries and breaking changes, and will be closing for the beta in one week. Also, if you're ready, you can also add your libraries' changes to the release notes at: < https://github.com/boostorg/website/blob/master/feed/history/boost_1_69_0.q… > After editing the release notes, you should get a form to create a pull request, remember to submit it, otherwise I won't see your change. As always, the calendar for the release cycle is available at: https://www.boost.org/development/ Thanks, -- The Boost Release Team

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[Release 1.70] Master branch is now closed for the beta
by Marshall Clow 07 Mar '19

07 Mar '19

Except with explicit permission by a release manager. Do whatever you want on develop, just don't change master. We'll re-open master after the beta. As always, check the calendar at https://www.boost.org/development 6-Mar: Boost 1.70.0 closed for all changes 13-Mar: Boost 1.70.0 beta; master branch re-opened 2-Aug: Release closed for all changes, except by permission of a release manager. 3-Apr: Boost 1.70.0 closed for all changes 10-Apr: Boost 1.70.0 release -- The release managers

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[build] Boost.Build/develop broken with msvc?
by John Maddock 07 Mar '19

07 Mar '19

Currently I see: D:/data/boost/boost/tools/build/src/tools\msvc.jam:1388: in configure-really *** argument error * rule generate-setup-cmd ( version : command : parent : options * : cpu : global-setup ? : default-global-setup-options : default-setup ) * called with: ( 14.16.27023 14.11.25503 : D:/compilers/visual studio/2017/VC/Tools/MSVC/14.11.25503/bin/HostX64/x64 : D:\compilers\visual studio\2017\VC\Tools\MSVC\14.11.25503\bin\HostX64 : <command>D:\compilers\visual studio\2017\VC\Tools\MSVC\14.16.27023\bin\Hostx64\arm\cl.exe <command>D:/compilers/visual studio/2017/VC/Tools/MSVC/14.11.25503/bin/HostX64/x64/cl.exe : i386 : : x86 : vcvars32.bat ) * extra argument 14.11.25503 D:/data/boost/boost/tools/build/src/tools\msvc.jam:1003:see definition of rule 'generate-setup-cmd' being called D:/data/boost/boost/tools/build/src/tools\msvc.jam:393: in configure D:/data/boost/boost/tools/build/src/tools\msvc.jam:345: in msvc.init D:/data/boost/boost/tools/build/src/build\toolset.jam:44: in toolset.using D:/data/boost/boost/tools/build/src/build\project.jam:1104: in using C:\cygwin64\home\John Maddock\user-config.jam:46: in modules.load D:/data/boost/boost/tools/build/src\build-system.jam:255: in load-config D:/data/boost/boost/tools/build/src\build-system.jam:453: in load-configuration-files D:/data/boost/boost/tools/build/src\build-system.jam:607: in load D:\data\boost\boost\tools\build\src/kernel\modules.jam:295: in import D:\data\boost\boost\tools\build\src/kernel/bootstrap.jam:139: in boost-build D:\data\boost\boost\boost-build.jam:17: in module scope Master is fine BTW. Best, John. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

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[interprocess] support for a new synchronisation mechanism
by Dudi Likvornik 06 Mar '19

06 Mar '19

Hi, My name is David, I would like to suggest a new synchronisation mechanism based on linux futex. as far as I saw, its not being supported as of now with in the interprocess communication library. One suggestion is to support a mutex, here is an example, possible partial implementation, based upon the following paper: http://dept-info.labri.fr/~denis/Enseignement/2008-IR/Articles/01-futex.pdf Mutex::Mutex(): m_word(UNLOCK) {} void Mutex::lock() { int lockState = UNLOCK; if(std::atomic_compare_exchange_strong(&m_word, &lockState, static_cast<int>(LOCK_SINGLE)) == false) { if(lockState != LOCK_MANY) lockState = std::atomic_exchange(&m_word, static_cast<int>(LOCK_MANY)); while(lockState != UNLOCK) { #if defined(__linux) syscall(SYS_futex, &m_word, FUTEX_WAIT, LOCK_MANY, nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wait is not being supported by current platform"); #endif lockState = std::atomic_exchange(&m_word, static_cast<int>(LOCK_MANY)); } } } void Mutex::unlock() { if(std::atomic_fetch_sub(&m_word, 1) == LOCK_SINGLE) return; m_word = UNLOCK; #if defined(__linux) syscall(SYS_futex, &m_word, FUTEX_WAKE, 1, nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wake is not being supported by current platform"); #endif } bool Mutex::try_lock() { int lockState = UNLOCK; return std::atomic_compare_exchange_strong(&m_word, &lockState, static_cast<int>(LOCK_SINGLE)); } ————————————————————————————————————————————————————————— And a conditional variable: Condition::Condition(): m_command(SLEEP), m_waitersCount(0){} void Condition::signal(Command command) { m_wakeLock.lock(); if(m_waitersCount == 0) { m_wakeLock.unlock(); return; } m_command.store(command, std::memory_order_relaxed); #if defined(__linux) syscall(SYS_futex, &m_command, FUTEX_WAKE, command == NOTIFY_ONE ? 1 : std::numeric_limits<int>::max(), nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wake is not being supported by current platform"); #endif while(m_command.load(std::memory_order_relaxed) != SLEEP && m_waitersCount.load(std::memory_order_relaxed) != 0){} m_wakeLock.unlock(); } void Condition::wait(std::unique_lock<core::Mutex> &lock) { m_waitersCount++; lock.unlock(); while(true) { while(m_command.load(std::memory_order_relaxed) == SLEEP) #if defined(__linux) syscall(SYS_futex, &m_command, FUTEX_WAIT, SLEEP, nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wait is not being supported by current platform"); #endif int fromCommand_one = NOTIFY_ONE; if(m_command.compare_exchange_strong(fromCommand_one, static_cast<int>(SLEEP), std::memory_order_relaxed)) { m_waitersCount--; lock.lock(); return; } else if(m_command.load(std::memory_order_relaxed) == NOTIFY_ALL) { if(m_waitersCount.fetch_sub(1, std::memory_order_relaxed) == 1) m_command.store(SLEEP, std::memory_order_relaxed); lock.lock(); return; } } } ConditionVariable::ConditionVariable() {} void ConditionVariable::wait(std::unique_lock<core::Mutex> &lock) { m_condition.wait(lock); } void ConditionVariable::notify_one() { m_condition.signal(Condition::NOTIFY_ONE); } void ConditionVariable::notify_all() { m_condition.signal(Condition::NOTIFY_ALL); } class ConditionVariable { public: ConditionVariable(); ConditionVariable(const ConditionVariable&) = delete; ConditionVariable& operator=(const ConditionVariable&) = delete; void wait(std::unique_lock<Mutex>& lock); template<typename Predict> void wait(std::unique_lock<Mutex>& lock, const Predict& predict) { while(predict() == false) m_condition.wait(lock); } void notify_one(); void notify_all(); private: Condition m_condition; }; Your thoughts of the idea, if any. p.s. Please be soft, its my first post ever :).

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Boost.uBLAS [gsoc19]
by Sarthakag 06 Mar '19

06 Mar '19

Hello, I am Sarthak Agarwal, 3rd-year undergraduate student from Birla Institute of Technology and Science, Pilani - Goa, India currently pursuing a double major MSc. Mathematics and B.E. Computer Science and Engineering. I am an active Competitive Programmer on various online judges for the last 4 years. I am comfortable in C/C++(STL) and Python(Django). I wish to contribute to Boost.uBLAS, specifically to Project 4 on implementing non-negative matrix factorization(NMF). I would also like to know if there are any upcoming ideas to implement in Boost.intrusive. I have completed the Boost Competency test and learned a lot while doing it. How can I share it for valuable feedback? I look forward to your guidance. Sarthak Agarwal -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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Regarding GSOC'19
by Keshav Gupta 05 Mar '19

05 Mar '19

Hi I am Keshav Gupta from India and wanted to work with Boost during GSOC 2019 on the major topic of Boost GIL. So can you tell me how to proceed with? Regards Keshav Gupta

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[variant2] Need rationale for never-empty guarantee
by Andrzej Krzemienski 04 Mar '19

04 Mar '19

Hi Peter, Thank you for writing and sharing this implementation of variant. I am sorry if I am bringing back an issue that has been already discussed and solved before, but I do not understand the rationale behind doing compromises in order to provide the never-empty guarantee. The short rationale provided in Boost.Variant library: https://www.boost.org/doc/libs/1_69_0/doc/html/variant/design.html#variant.… was provided before we got C++11 the moved-from state in the language. Today, it should come as no surprise to programmers that a type might be in a "moved from" state where only a limited interface of an object can be used. The guarantee provided by variant's assignment is not a strong exception safety guarantee: it is possible that my variant has value A, I want to assign value B, and (due to an exception) I end up with value C. If this happens, the only thing I can reasonably do is to either abandon whatever I was doing or reset the variant to the state that I need. So the guarantee that it is not left empty does not seem to be of much use. But the cost to be paid is noticeable. I think that this question should be addressed in the documentation. Regards, Andrzej

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[gsoc19][astronomy] Code for review
by Avinal Kumar 04 Mar '19

04 Mar '19

where should I submit my code for programming competency test ??

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Mentors invitations
by David Bellot 04 Mar '19

04 Mar '19

Dear Boost C++ mentors, it seems we only have 5 mentors this year. It's not a lot. Usually, we have one student per mentor, but we also have 6 to 8 students as well. We need at least one or two mentors more. I've just sent the invite from the GSOC website to become a mentor. If you didn't receive it yet, it's surely because I forgot your name. Can you please send me a reminder now with your correct email address? If you didn't propose to become a mentor but want to now, please let me know as well. Cheers, David

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GSoC 2019 Introduction|Boost.Python-C++-Python Integration Project
by Roopkatha Samanta 04 Mar '19

04 Mar '19

Hi, I am Roopkatha Samanta, studying in 2nd year CSE (undergrad) at Jadavpur University, Kolkata, India. I am very well versed with programming languages like C, C++, Python and Java. I am very much into mathematics too and also interested in machine learning and deep learning. Presenly I am working on two projects in domain of Image Processing as my undergrad project and also trying to develop games on my own. I would like to contribute toBoost.Python-C++-Python Integration Project as my GSoC 2019 Project. Kindly guide me through the process on how to start. Regards, Roopkatha Samanta

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[gsoc19] Logo
by Cem Bassoy 04 Mar '19

04 Mar '19

Hi, is there a chance to change the current logo on the organization list https://summerofcode.withgoogle.com/organizations/?sp-page=5 with https://de.wikipedia.org/wiki/Boost_(C%2B%2B-Bibliothek)#/media/File:Boost.… The current image on the google summer of code page does not look too good and all other organization have smooth ones. Best Cem

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GSoC 2019
by Shourya IIT B 04 Mar '19

04 Mar '19

Respected Sir, I am Parashuram Shourya from India. Currently, I am doing my Master’s in Geoinformatics from Centre of Studies in Resources Engineering(CSRE), Indian Institute of Technology Bombay(IITB). I have a Bachelor's degree in Computer Science and Engineering. Currently, I am learning Machine Learning and High-Performance Computing. I have vast programming experience in C, C++, Python I would love to contribute to The Qt Project in the upcoming Google Summer of Code 2019. I would be very grateful to get any directions to start with so that I can pursue and participate in GSoC 2019 with your organization.

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GSoC 2019: we're in again!
by David Bellot 04 Mar '19

04 Mar '19

Dear Boost community, this year again, Boost C++ has been accepted as a mentor organization for the Google Summer of Code 2019. We are very happy to be part of this program every year because it brings talented students and a substantial amount of money to our organization to support our work toward the best libraries in C++. If you want to be a mentor, please propose your project now here: https://github.com/boostorg/boost/wiki/Google-Summer-of-Code:-2019 It's very important to write your proposal as soon as possible to attract the best students. If you have any questions, please contact me immediately. If you happen to be in Sydney, come and have a chat with me directly. Happy coding, David

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Regarding project idea for GSOC 2019
by Syed Souban 04 Mar '19

04 Mar '19

Hi guys! I am a machine learning enthusiast looking forward to work in implementing some machine learning algorithms in c++ as a gsoc 2019 project. I know that a similar project has been done last year. So in a way I want to extend to that idea. I needed some suggestions and or pointers on which algorithms are feasible to implement. Regards, Souban

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(no subject)
by Roopkatha Samanta 04 Mar '19

04 Mar '19

I want to contribute to boost C++-Python integration project for my GSoC 2019 project.

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[Boost.Intrusive]
by PREET THAKKAR 03 Mar '19

03 Mar '19

I am a 2nd year computer science student. I want to contribute to Boost.Intrusive as part of GSoC '19. I have some ideas to enhance Boost.Intrusive and also add more features to previous year's project in Intrusive. I am new to Boost. Any help regarding getting started with the library would be appreciated. Regards, Preet Thakkar

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Re: [boost] Review request for variant2, review manager wanted
by Peter Dimov 03 Mar '19

03 Mar '19

> If anyone would like to step forward to manage the review, please do. Michael Caisse was the first to graciously offer his services (via Slack) and I'll be glad to have him manage the review. Thanks to Niall who also volunteered. :-) With respect to Niall's request for compile time and run time measurements, I've added a benchmark https://github.com/pdimov/variant2/blob/develop/benchmark/benchmark1.cpp and the results from compiling and running it on my machine are at https://github.com/pdimov/variant2/blob/develop/benchmark/benchmark1.md This is not a cherry-picked example that makes variant2 look good, so it loses to std::variant here and there. :-)

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Runtime code generation
by VIKRAM LODHI 03 Mar '19

03 Mar '19

I am trying to write a grammar based code but can't seems to find starting point. Is there anything I should go through first. Grammar based . All the functions are written in string formats by user and parsed into binary at runtime and are able to use that function.

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[release][multi_index] Permission to merge to master
by Joaquin M López Muñoz 03 Mar '19

03 Mar '19

I'm asking permission to merge the following fairly trivial changes to master: https://github.com/boostorg/multi_index/compare/bbb915bd344463ba767aebe7988… Travis and AppVeyor tests are passing. BTW, the conditions for allowed commits at this release stage ("closed for major changes") are not clear to me. Do I really need to ask for permission if the change (as is this case) is deemed minor? Joaquín M López Muñoz

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Re: [boost] [Boost-testing] Running regression tests for msvc-14.2 (preview)
by Tom Kent 02 Mar '19

02 Mar '19

On Tue, Feb 26, 2019 at 7:13 AM Mateusz Loskot via Boost-Testing < boost-testing(a)lists.boost.org> wrote: > On Tue, 26 Feb 2019 at 14:02, Tom Kent via Boost-Testing > <boost-testing(a)lists.boost.org> wrote: > > I was hoping to start running regression tests for the upcoming Visual > Studio 2019 (toolset 14.2) and got stumped by an issue. > > I've set a user-config.jam: > > using msvc : 14.2 ; > > Is this toolset even supported? > > As I explained in > https://lists.boost.org/Archives/boost/2019/02/245143.php, > I had to 'fake' it as 14.1 in project-config.jam: > > using msvc : 14.1 : "C:\\Program Files (x86)\\Microsoft Visual > > Studio\\2019\\Preview\\VC\\Tools\\MSVC\\14.20.27323\\bin\\HostX64\\x64\\cl.exe" > I was able to get the regression tests to run using this workaround in user-config.jam. Here's what the config_info is: https://www.boost.org/development/tests/develop/developer/output/teeks99-te… I'm disappointed that we can't have general support for future versions of msvc. We don't seem to have this problem with pre-release versions of GCC/Clang. https://www.boost.org/development/tests/develop/developer/output/teeks99-02… Tom

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Gsoc 2019 Boost.GIL project
by fady faragallah 02 Mar '19

02 Mar '19

Hi,I am fady faragallah 4th year student at faculty of computer engineering. I am interested in Boost.GIL and would like to contribute to the project. I have good experience in C++ programming and image processing algorithms and I am currently working on image processing and deep learning projects using convolutional neural networks. I need to know where I can deliver the competency test and how to contact the mentors. Thanks

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Interested in working on Boost.GIL
by AvZ NaV 01 Mar '19

01 Mar '19

Hello, I am Arnav Tiwari, a sophomore year undergraduate student of IIT Kharagpur. I am interested in working on Boost.GIL. I have prior experience in image processing and C++ so I feel I will be able to pick up the project and get to work quickly. I would really appreciate it if someone can point me in the right direction to get started. I hope I'm not spamming the mailing list, apologies if that is the case. -- Regards, Arnav Tiwari

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Re: [boost] [variant2] Need rationale for never-empty guarantee
by Nikita Kniazev 01 Mar '19

01 Mar '19

> This reply actually addresses my question: visitation on boost::variant2 is > faster than on std::variant because it does not have to account for the > valueless state. I would not expect perfomance differences on CPUs with branch predictor or if visitation translated into jump table (variant uses switch for this?). > For example, resizing a std::vector implements the strong guarantee that > state will be restored to before the resize if an exception is thrown in > the middle of the resize. Probably one should use different container type if a data types move/copy can throw. There even a vector implementation that will not copy/move on resize https://www.youtube.com/watch?v=Ke1mJiGO-pU (for CPU with virtual memory).

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[appveyor] basic question
by Raffi Enficiaud 01 Mar '19

01 Mar '19

Hi Boost, Can somebody explain me like I am 5 what I need to do in order to activate Appveyor builds for boost.test? I am not admin of the repository. Thanks! Raffi

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