June 2018 - Boost - lists.stage.boost.cppalliance.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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[RFC] unique_val (handles, IDs, descriptors...)
by Miguel Ojeda 15 Oct '18

15 Oct '18

Hi all, While working on a medium-sized project, I had to wrap quite some handles, IDs, descriptors, etc. into RAII classes. Somehow, writing those and making them movable seemed more verbose than needed. I searched in the STL and Boost for something already implemented, but nothing seemed to come up. I decided to write my own prototype to see whether I was missing something important; but actually using it in my project felt quite natural and simple. At this point, I asked for a second opinion from a well-known expert (thanks Scott!) and he agreed that it seemed like a reasonable idea but, of course, he would also be surprised if others haven't come up with something similar. So I polished it up a bit and uploaded it to: https://github.com/ojeda/unique_val Below you have the introduction inlined [1]. If you have the time, please take a look (specially to the Rationale) and let me know your comments. The code itself is very short and straightforward. If you already have this class/template in Boost somewhere that I missed, please let me know! Otherwise, if you think this could be interesting to put into Boost in some existing library (not sure which) or as a new tiny library, I would be glad to make the effort to expand it, clean it up, etc. Thank you! Miguel [1] """ A single-header header-only library for representing unique values (handles, IDs, descriptors...) that default to a value on move for C++11, C++14 and C++17. It simplifies writing resource-owning classes (RAII) with move semantics support for resources with handles, IDs or descriptors that are supposed to be used as unique values, not as unique pointers. For instance, it can be used with non-pointer handlers (like the `int` file/socket descriptors in POSIX) and with opaque pointer handlers (like the `HWND` handles in the Win32 API). As such, it can be used as an alternative to `std::unique_ptr` with or without custom deleter, specially for resources that use a non-pointer type or resources that are not simply heap-allocated. It does not have any overhead compared to using the original type. It supports booleans, integers, pointers and enumerations. The default value can be different than the default-constructed value (i.e. different than 0, nullptr, etc.). """

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Original STL Library Documentation has been recovered and is now safe forever.
by Robert Ramey 02 Sep '18

02 Sep '18

The Standard Template Library is the foundation of modern C++. The creation and publication of this code and its documentation set a new standard for the formal specification of what a computer program should do, how it should be designed and how it should be formally documented. These pages were maintained first by Silicon Graphics and then later by Hewett-Packard. In January of 2018 these pages were removed by H-P. This is a historic blunder. I have recovered the original STL Library Document and hosted them here: http://www.rrsd.com/software_development/stl/index.htm Robert Ramey

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Strange libstdc++ versions in travis-ci testers
by Andrzej Krzemienski 15 Aug '18

15 Aug '18

Hi Everyone, Maybe someone could help me understand the configuration on the travis-ci testers. Whenever I push a new commit I get a number of failures from travis-ci about missing std::is_trivially_default_constructible from the standard library; like here: https://travis-ci.org/boostorg/optional/builds/397519342?utm_source=email&u… Some tests with Boost.Predef indicate that they are clang compiler 3.X, and clang 5 with libstdc++ of strange version nubers: macro BOOST_LIB_STD_GNU gives values 450400026 and 460700026, which would correspond to releases 2015-04-26 and 2016-07-26, but when I look at the release notes for GCC there are no releases mentioned of these dates: https://gcc.gnu.org/news.html Maybe someone knows what versions of libstdc++ these are? Or maybe I am missing something obvious? Regards, &rzej;

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Docker environment(s) for Boost Development
by James E. King, III 26 Jul '18

26 Jul '18

I submitted a pull request into the superproject containing some docker scripts. The intention of this is to simplify managing a docker build environment for boost: https://github.com/boostorg/boost/pull/184 I'm wondering if folks will find this useful, and whether folks think this should be in its own submodule instead of being in boostorg/boost. I only have an Ubuntu Bionic environment in this pull request but it wouldn't be that difficult to add debian, centos, and others, as well as various versions of each. I have tested it on Unix and on Windows. On Unix the performance is quite good overall - but on Windows since they use SMB to do the sharing it is really slow (I would say a good 20 times slower between typing "b2" and getting the first output as it scans through all the files. I would recommend continuing to use a virtual machine on Windows Hosts for unix boost development, but this option is there and hopefully they will improve things. This partially came out of the discussion we had a number of months back about how we handle third party dependencies. For the most part one has to look at README files in various locations to learn about them. This is an attempt to pull all the dependencies together for a complete build into one place (the Dockerfile). One day when Microsoft supports Visual Studio compilation inside a reasonably sized windows container (i.e. based on nanoserver and not Windows Server Core), I'd like to add that as well since managing the dependencies on Windows is a bit harder (you usually have to build them). Thanks, Jim

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Looking for help on preparing for review
by Damian Vicino 20 Jul '18

20 Jul '18

Hi, I'm preparing my library safe_float to be proposed for review. The library was born in the GSOC2015, but it never reached a review ready state. My plan is to change that in the next few months. At this point, I'm looking for some volunteers to proof-read the documentation. Code is going through major rewrite, and I will send another mail looking for help with reviewing the code when that is done. The most current documentation can be read directly from the web here: https://sdavtaker.github.io/safefloat/ Any comment is appreciated. Best regards, Damian

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Boost.Signals deprecation and removal
by James E. King, III 15 Jul '18

15 Jul '18

This first implementation of signals has been deprecated since the 1.54 release. (When) are we going to remove it? It is under management of the CMT, and it has been deprecated for over 10 major releases. I would like to suggest we remove it in the Boost 1.68.0 release. - Jim

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[Boost.Serialization] Help with PR fixing a memory leak in the current version
by Alexander Grund 12 Jul '18

12 Jul '18

Hi, TLDR: I would like https://github.com/boostorg/serialization/pull/105 to be merged for the next Boost release to fix a memory leak and need someone to review this or help getting it merge-ready. Details: Some time ago I made an analysis of a crash introduced in Boost 1.65.0 in the serialization part. The details are quite complicated as the cause is static initialization/destruction order in shared libraries which may even depend on compilers (could not confirm) or standard libraries (dito, observed in all tested versions). It boils down to a violation of the expected destruction order in the case of shared libraries. I observed how 2 global instances of the same type but from different shared libs are destroyed together although the 2nd should not yet be which causes a use-after-free from another global instance. The Singletons involved did have methods to detect, whether they are active or destroyed but they were kinda optimized away in Boost 1.65 leading to a crash which makes the whole library unusable. Not understanding the root cause of the crash lead to changing the singleton to use dynamic allocation, but not freeing it which leads to the memory leak that is currently in Boost. The current state of the develop-branch changed this back to the crash situation we had before making it unsuitable for the next release. Another pair of eyes would be great to check the PR and get this finally fixed. Thanks, Alex

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python::numpy not built on windows binary installers
by Nicholas Devenish 07 Jul '18

07 Jul '18

Hi All, I just downloaded the windows boost binaries from https://dl.bintray.com/boostorg/release/1.67.0/binaries/, linked from the boost downloads page. They are missing the boost_numpy library. This (silently) doesn't build if the python installation that boost finds is missing numpy. This is listed as "Third Party" so apologies if this is the wrong place to report it - but it's not clear from the page who makes them. I also couldn't find any mention of this, so don't know if it's a deliberate exclusion. Nick

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[MultiIndex] Hinted insertion for multiple indices?
by Gareth.Sylvester-Bradley＠sony.com 04 Jul '18

04 Jul '18

Is there a way to provide insertion hints for multiple indices in a multi_index_container? In a particular example, I have a container with several ordered_non_unique indices, and for the majority of insertions, the value will end up at the end of these indices. I'm looking for a way to provide the index.end() hint for all of these indices? (Or maybe alternatively, to relax the stability/insertion-order guarantee?) Thanks, Gareth

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