October 2018 - Boost - lists.preview.boost.org

[intrusive] static_assert(sizeof(caster)==sizeof(int))
by Vinnie Falco 18 Oct '18

18 Oct '18

A user is reporting a static assert on compilation: <https://github.com/boostorg/beast/issues/1270> Any ideas? Thanks

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Boost header isolation testing
by James E. King III 16 Oct '18

16 Oct '18

In the winapi project there's a neat little Jamfile rule that will ensure each public header will compile properly (i.e. it is not missing any #include statements). I pulled this into uuid when I started maintaining it, and I find myself pulling it into another repository. It would be nice to have this as a standard Boost.Build rule that one could easily add to test Jamfiles. Is there anything like this that exists right now in Boost.Build? - Jim

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Boost CMake support - Request for Comment
by Robert Ramey 16 Oct '18

16 Oct '18

Background ========== My personal knowledge of build systems is somewhat limited. a) I don't really understand CMake all that well. I have made CMakeLists.txt files for both the serialization library and the safe numerics libraries as an aid to build and maintain IDE and make files used in running tests and posting results to CDash. b) I don't really understand our current system, Boost Build, very well either. I've made jam files for building and running tests for the serialization and safe numerics libraries. c) I recently reviewed C++Now 2017: Daniel Pfeifer's excellent video from C++Now 2017 “Effective CMake" - https://www.youtube.com/watch?v=bsXLMQ6WgIk . I recommend it highly. Despite my lack of knowledge in this area, or perhaps because of it, I've volunteered to direct the effort to evolve Boost so that users of Boost can avail themselves of the benefits of CMake. This effort will be organized as follows: a) A discussion on the boost developers mailing list with the goal of reaching a consensus as to what benefits CMake can and should provide to users and developers of Boost. This effort will commence with the posting of this notice. I hope that this discussion can be more or less resolved within 30 days. b) I will then synthesize from the above discussion a call for proposals which lists the requirements and requirements. c) Those proposing CMake for boost will have approximately 90 days to prepare their proposals. Their proposal are expected to look similar to a boost library proposal. That is they are expected to have some (CMake) code, along with tests, documentation including tutorials and reference. This is only an expectation. It's conceivable that such a proposal might only contain conventions and and samples of what boost library should contain to fulfill the requirements. As with boost libraries, submissions are not required to totally complete. But they have to be sufficiently complete to convince reviewers the the submission fulfills the stated requirements and can be finished in good time. d) After the 90 day period, submissions will be reviewed simultaneously. Note that this is at a variance from normal boost procedure of reviewing submissions one at a time. Since we expect to receive a number of submissions and only one can be accepted, the normal boost protocol can't really function. Target date for this review is 1 February 2019. e) After the review period the review manager will prepare a report which includes the decision of which submission will be accepted into the official boost distribution. Currently, I, Robert Ramey, expect to be review manager. However, it's possible that this by the time the review is undertaken, this coveted position could be assigned to some more worthy candidate. Scope, Requirements and Features ================================ We presume that submissions will fulfill the applicable requirements of any boost submission. In addition we would like to see the following addressed. Library Build ------------- “Effective CMake" - https://www.youtube.com/watch?v=bsXLMQ6WgIk Recommends that all libraries - including header only libraries have a CMakeList.txt file. What should this include for Boost Libraries? Library Test ------------ Should facilities for "testing" be only done by developers? or should users who acquire library packages also be able to test libraries. Should CMake testing results posting be used - CDASH? Should we just skip the issue of Library Testing and continue to depend on Boost Build. Library Packaging ----------------- Is the library packaging facility provide by CMake - CPACK - useful to boost. Should boost libraries be updated to support it? Dependencies ------------ If the above is implemented, can we depend upon CMake to handle library dependencies? Or does some special functionality Do circular dependencies constitute a problem? Modularity ---------- Currently boost is organized as a tightly integrated group of libraries. This organization manifests itself in a number of ways. We have a Boost "super project" in github. Boost libraries are "sub projects" of this super project. This known structure is exploited by and depended upon by boost tools. Should CMake support continue this policy/design. We distribute boost as "super project". Should we continue to do this or distribute libraries on a library by library basis. Does CMake/CPACK etc. make this "simple"? Documentation/testing --------------------- What support should be require for uses of Boost CMake implementation. Documentation, examples, templates for helping library developers. How should the CMake design/implementation be tested? Other considerations -------------------- add your requirement/features here. Useful Resources =============== “Effective CMake" - https://www.youtube.com/watch?v=bsXLMQ6WgIk https://gist.github.com/mbinna/c61dbb39bca0e4fb7d1f73b0d66a4fd1 https://github.com/purpleKarrot/Boost.CMake https://www.youtube.com/watch?v=eC9-iRN2b04 Please try to keep this discussion on this list. I know that there has been a lot going on on slack. But having it in two places makes it harder for me to review and summarize. Also slack doesn't conveniently maintain comment hierarchy. So please try to keep this discussion on this list. Robert Ramey

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Re: [boost] "peer reviewed" - Rights and responsibilities of maintainers
by Bjorn Reese 16 Oct '18

16 Oct '18

On 10/16/18 9:59 AM, Alexander Grund via Boost wrote: > So again: What is the Boost course on reviews of existing libraries and > the statement on the rights and responsibilities of maintainers? https://www.boost.org/community/reviews.html#Maintainer

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[program_options] custom validator overrides
by Roger Martin 16 Oct '18

16 Oct '18

Hi, The Custom Validators documentation https://www.boost.org/doc/libs/1_68_0/doc/html/program_options/howto.html shows void validate(boost::any& v, const std::vector<std::string>& values, magic_number* target_type, int) { but the possible templates don't match; the last variable type is an int; the key is matching this last type: int goes with std::vector<T>* long goes with T* it also seems possible to hit the void validate(boost::any& v, const std::vector<std::basic_string<charT> >& s, boost::optional<T>*, int) { where it then calls for get_single_string and if you are trying for a multitokens switch args, it'll throw " only takes a single argument". which also varies if it was parsed by command_line_parser or parse_config_file command_line_parser: vector size can >= 1 up to number of switch args parse_config_file: vector size ==1 no matter what the number of args are on the input. just one string with all switch args. This was tested with 1.65 yet I don't see anything changing in https://github.com/boostorg/program_options/blob/develop/include/boost/prog…

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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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bjam question about "requires" negation
by James E. King III 13 Oct '18

13 Oct '18

I want to run a test that should run without explicit operator conversion capability and fail to compile with explicit operation conversion capability, but I'm not sure how to negate the requires statement. I'm sure it's trivial but I found no examples. I tried a bunch of things but none worked. [ run implicit_conversion.cpp : : : [ requires NO cxx11_explicit_conversion_operators ] : implicit_conversion ] [ compile-fail implicit_conversion.cpp : [ requires cxx11_explicit_conversion_operators ] : explicit_conversion ] How do I properly implement the "NO" part? Thanks, Jim

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[parameter] An offer to help maintain and improve the library
by Cromwell Enage 13 Oct '18

13 Oct '18

Hello, everyone. It took me a while to get around to this, but here goes. I've been a long-time user of Boost libraries, although life events imposed a bit of a hiatus until recently. But now I have the opportunity to help out some more, and one of the ways I want to give back to this community is by helping to maintain and improve Boost.Parameter. I participated in the review of this library before it was accepted, so I'm familiar with its capabilities and code structure. In addition to fixing any bugs and handling pull requests, I'd like to make the following improvements, which I will summarize here: * Add macros to generate Boost.Parameter-enabled function call operators. * Add parameter category qualifiers "consume", "move_from", and "forward". (Current qualifiers are "in", "out", and "in_out".) * Fix parameter::parameters::operator() so that it also accepts non-const rvalues. * Be no longer bound by BOOST_PARAMETER_MAX_ARITY on compilers that support perfect forwarding. * Enable parameter::template_keyword<> to accept function types. * Remove the necessity of wrapping boost::ref() around non-const lvalues. I can discuss each of these bullet points in separate threads if necessary. I await your feedback! Cromwell D. Enage

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Boost xxhr ? High level http client library
by Damien Buhl 13 Oct '18

13 Oct '18

Dear Boost, I've built an header-only library based on Boost.Beast which allows you to perform HTTP requests. It is implememented with two backends : * Boost.Beast for native builds. * XmlHttpRequest for WebAssembly (plans to migrate to fetch API which is richer) Actually Boost.Beast is a great lib, however it's API is thought to build HTTP centric app not just to make some simple HTTP call ( as for example urdl was ). xxhr on the other hand is about making it simple to call an HTTP service. Usage example : GET <https://nxxm.github.io/xxhr/html/namespacexxhr.html#a69bafa24d7c33b004a7de8…>( "http://httpbin.org/anything"s, on_response = [](auto&& resp) { std::cout << resp.text; }); I would be really interested in a pre-review or some feedback about it's API. The implementation merits more attention and can significantly be improved but this email is to grab a first feedback from the community. Documentation : https://nxxm.github.io/xxhr/ GitHub : https://github.com/nxxm/xxhr Example code relying on it : nxxm/gh <https://github.com/nxxm/gh>: partial GitHub API implementation Thanks for your time :) -- Damien Buhl Software Developer +33 6 77 43 10 05 https://nxxm.github.io/

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Test matrix file read errors?
by James E. King III 11 Oct '18

11 Oct '18

I'm trying to look at the develop test matrix for a couple repositories and I am getting an error: Error extracting file: Error code 9 - The specified zipfile was not found *(the > file exists, so this is probably an error reading the file)*. https://www.boost.org/development/tests/develop/developer/date_time.html https://www.boost.org/development/tests/develop/developer/dynamic_bitset.ht… Thanks, Jim

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