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[review][mp11] Review report
by Bjorn Reese 03 Aug '17

03 Aug '17

I. VERDICT Mp11 is accepted unconditionally into Boost. There were 14 accept votes and 1 conditional accept vote. See list at end of this report. II. DESIGN Reviewers evaluated the design as very good. Many agreed with the design principle of using template aliases on type lists, which means that Mp11 can be used on std, boost, and custom type lists. Integration with MPL was discussed. This resulted in a new header file <boost/mp11/mpl.hpp> that enables the conversion between mp_list (and std::tuple) and MPL sequences. A version of mp_eval_if that can apply a metafunction to type lists in both the true and false branch was requested. This is not possible due to C++ limitations (template parameter pack must be at the end.) Instead two alternatives were suggested: (1) use a nested mp_eval_if in the true branch, or (2) use mp_if<>::type with mp_defer in both branches. Extra metafunctions were added for working with map and sets: mp_is_set, mp_is_map, and mp_map_keys which returns a list of all keys. No review without a discussion about names. The mp_ prefix received most comments. The prefix is used to avoid collision between mp11 names and C++ keywords. The argument against the mp_ prefix was that MPL and other Boost libraries already have established trailing underscore as the naming convention. The argument in favor is that the mp_ prefix is better suited for later C++ standardization. Other names that deviate from MPL, such as apply versus fn, were also pointed out, and the names of tuple operations were also discussed. III. IMPLEMENTATION The reviewers who looked at the implementation were generally pleased with its quality and simplicity. A faster version of mp_find was proposed during review. On reviewer pointed out that const lists causes obscure compilation errors. IV. DOCUMENTATION The evaluation of the documentation was more mixed. Some found it good, while others found it too terse. A recurring comment was that the documentation is missing beginner-level explanations and examples. For instance, the tuple_cat example was mentioned as being too advanced for an introduction. More examples with higher-order metafunctions (e.g. mp_bind) was requested. The reference documentation does not state the pre-conditions of the metafunctions. For example, what happens when indices are out of bounds? The description of map (list of lists) lead to confusion. Mp11 map entries have one unique key-type, and zero or more value-types. The ability to have multiple value-types per key-type makes it possible to emulate multi-maps. Some where unsure whether C++11 or C++14 was required for the library. There were plenty of other useful comments that I will omit from the review report for the sake of brevity. V. USEFULNESS The library was generally deemed useful. It was discussed if C++11 (and later) makes it too easy to write our own metaprogramming utilities, and thus not needing a metaprogramming library. This was not directed at Mp11 in particular. Some of the arguments in favor of a metaprogramming library were better performance and portability. I would like to add another advantage of a metaprogramming library, namely that it gives us a common vocabulary. VI. CONCLUSION The library fulfills the quality and usefulness criteria without major outstanding issues. The library is therefore cleared to be included into Boost. My main recommendation as review manager is to make the documentation more beginner-friendly before the library is added to Boost. This is a recommendation, not a requirement. VII. PARTICIPANTS The following formal reviews were posted: * Barrett Adair : Accept * Brook Milligan : Accept * Edward Diener : Accept * Glen Fernandes : Accept * Jason Rice : Accept * Joaquin M López Muñoz : Conditional accept * John P Fletcher : Accept * Lee Clagett : Accept * Paul Fultz : Accept * Peter Koch Larsen : Accept * Robert Ramey : Accept * Roberto Hinz : Accept * Vijayan : Accept * Vinnie Falco : Accept * Zach Laine : Accept I would like to thank all participants for their efforts. I would also like to thank Peter Dimov for bringing such a high-quality library to Boost.

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Warning generated by boost::process code
by Wilfred Smith 02 Aug '17

02 Aug '17

Dear Sir or Madam, In Boost 1.64.0, include/boost/process/detail/posix/wait_group.hpp:131:10: warning: unused variable 'start' [-Wunused-variable] auto start = std::chrono::system_clock::now(); ^ /usr/local/include/boost/process/detail/posix/wait_group.hpp:165:10: warning: unused variable 'start' [-Wunused-variable] auto start = std::chrono::system_clock::now(); ^ I believe these two lines should be removed. This appears to be a “copy and paste” issue. The two routines above these lines use the “start” variable to calculate a relative time. However, the later two routines use an absolute time, and the compiler complains as shown above. Removing these two lines should fix the compiler warning and have no adverse effect. Please let me know if this is the wrong place to complain about issues. \W/

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Boost::Process is broken
by Wilfred Smith 02 Aug '17

02 Aug '17

All, Has anyone tried to build with <boost/process.hpp> included using XCode 9.0? I don’t think this went through code review. include/boost/process/exception.hpp:22:30: error: using declaration cannot refer to a constructor using std::system_error::system_error; ~~~~~~~~~~~~~~~~~~~^ I’m not sure that does what was intended, and the compiler thinks it’s silly talk… Any and all assistance appreciated in advance… \W/

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Reminder: Boost Master branch will close for the 1.65.0 release on Wednesday
by Marshall Clow 02 Aug '17

02 Aug '17

Get your bug fixes and documentation updates in now! -- Mashall Upcoming release schedule: 2-Aug: Release closed for all changes, except by permission of a release manager. 5-Aug: Boost 1.65.0 closed for all changes 9-Aug: Boost 1.65.0 release

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[numeric_conversion] Compilation errors with msvc-14.1 and std:c++latest in master branch
by Adam Wulkiewicz 02 Aug '17

02 Aug '17

Hi, I noticed there are compilation errors in master branch and not in develop branch. Only runs with cxxflags= std:c++latest are failing. See e.g.: http://www.boost.org/development/tests/master/developer/output/teeks99-09-q… Affecting Geometry: http://www.boost.org/development/tests/master/developer/output/teeks99-09-q… Regards, Adam

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[release-1.65] changes in master
by Oliver Kowalke 01 Aug '17

01 Aug '17

Will commits that have been added to branch master in the last days be included into release 1.65? ty, Oliver

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[BB++] 17 minutes long documentary
by Phil Bouchard 01 Aug '17

01 Aug '17

Like I promised, here's a 17 minutes long documentary on BB++ which now shows its internals: https://youtu.be/GrNDYWyasxg Regards, -Phil

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[outcome] Outcome v2 has reached stability, WG21 paper will be P0762R0
by Niall Douglas 31 Jul '17

31 Jul '17

For boost-dev's information: https://www.reddit.com/r/cpp/comments/6qo1m3/outcome_v2_has_reached_stabili… --- cut -- I am pleased to announce that Outcome v2, rewritten to fulfil the Boost peer review feedback from May and only reaching feature completeness three weeks ago, has been successfully deployed into two complex libraries which were heavily using Outcome v1. Lots of bug fixes and maturity has resulted, and if you were holding off on deploying Outcome into your own code until now, now is the time! The code itself is now ready for a second Boost peer review, it has all the same testing that v1 had, and I am highly confident as to its quality. What solely remains before Outcome v2 can reenter the Boost peer review queue for a second review is the documentation which remains parlous (and any help with it is greatly appreciated!), and the "Boostification" cronjob script as the peer review wants a "pure Boost" submission. I am also going to have to fix a number of bugs in Standardese the documentation tool first, it currently segfaults when fed the Outcome headers :). @foonathan's tool shows lots of promise, it does far better with C++ 17 than doxygen, just need to shave off some rough edges in the tool. What comes before that though is writing a WG21 paper P0762R0 summarising the Boost peer review which led to the stripped down, barebones v2 `result<T, E>` design and the rationale for the design deviations from `expected<T, E>` as according to the Boost peer review feedback. If WG21 feel warm feelings about a `std::result<T, E>` after reading P0762R0, then I will prepare a formal standardisation proposal for the Library Evolution Working Group (LEWG) and get the ball rolling for standardisation by attending meetings from 2018 onwards until it's through. I'll announce any draft D0762R0 here when it's ready for people to comment and give feedback on soon. My thanks to everyone here on Reddit, on boost-dev, on SG14 low latency, and privately who have helped out with testing, documentation, and so much more in making this library happen. I know those coming from Rust-land feel amazement how long it has taken C++ to replicate Rust's `Result<T, E>`, but I'm very sure ours is enormously superior to theirs already simply by doing so much less because it doesn't need to. Taking time to get design **right** is one of the big things which continues to separate C++ from the upstart systems programming languages. Long may it continue! --- context --- Outcome provides a C++ 14 STL-quality `result<T, EC>` and an `outcome<T, EC, E>` implementation of success|failure value transports, and is expected to pass a second Boost peer review and be submitted for C++ standardisation as the lowest level of an overall framework as proposed by: - http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0650r0.pdf C++ Monadic interface - http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0323r2.pdf A proposal to add a utility class to represent expected object (Revision 4) The idea is that result/outcome are the extremely lightweight struct-like success|failure value transports suitable for usage in public APIs, whereas expected is the much richer variant-like monadic success|failure value transports, and everything participates together under P0650R0. Outcome is a pure header only library with no dependencies. It works best with C++ 17 and Concepts enabled, but can work with C++ 14 on these compilers or better: - clang 4.0 (5.0 required for Windows) - GCC 7 (VS2017 Update 3 RTM is supposed to work too according to Microsoft, my thanks to them for swiftly fixing the several ICEs I reported) Github: https://github.com/ned14/outcome Docs (highly incomplete): https://ned14.github.io/outcome/ Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

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Boost 1.65.0 Beta 1
by Marshall Clow 31 Jul '17

31 Jul '17

Boost release 1.65.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.65.0.beta.1/source/> The SHA256 checksums are as follows: d54d29568c4e4933cbfe40a292b6cb84a7f68121e34f6a83f7d0f7c652b6b2d8 boost_1_65_0_beta1.7z 092676557513e992347d30dd0cd058fb8af2a401e5da4f4413f5b577852d726b boost_1_65_0_beta1.tar.bz2 31fa3c807e2205e18f7d5c74f77f540677f7b0937af1e37f595c137e1e87bf84 boost_1_65_0_beta1.tar.gz 83c8d8b76fa9591572226a1a49fd191d76db3011b52b907cbbc8d37d46213bd2 boost_1_65_0_beta1.zip Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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[Boost] file transfer
by vikram.smvdu 31 Jul '17

31 Jul '17

I recently started learning asio. Documentation is very awesome. I am planing to make a server where there is a file base. And client can login or connect and access the file.. is this possible. I am unable to send data from client to server.. server can sent but vise versa is not implemented by me.. i am trying.. if any body can point me a direction.. it will be much helpful Thank you Regards V Sent from Samsung Mobile

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