March 2017 - Boost - lists.preview.boost.org

[gsoc17] boost.geometry
by Aman Gupta 20 Mar '17

20 Mar '17

Respected sir/ma'am I, Aman Gupta, want to contribute in Boost.Geometry; mainly in Project 1(Filtering of compare distance predicates) and Project 3( Nearly antipodal points distance accuracy improvement) . I have good knowledge in geometry and want to learn more . For the problem given in Project 1, another approach I can suggest is to get 2 intersections of plane (which would be ellipse) with the help given points and compute the respective distances using those ellipses. I hope to get selected for the project work. Thanking You. AMAN GUPTA resume: https://drive.google.com/open?id=0B9HCqOWnVVvDcm9PQkYtczFjVmM

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Formal Review Request: mp11
by Peter Dimov 19 Mar '17

19 Mar '17

I'd like to request a review for mp11, a simple C++11 metaprogramming library. The library implements the approach outlined in my two articles http://pdimov.com/cpp2/simple_cxx11_metaprogramming.html http://pdimov.com/cpp2/simple_cxx11_metaprogramming_2.html and is available at https://github.com/pdimov/mp11/ It supports g++ 4.9 and above, clang 3.6 and above, msvc-12.0, 14.0, 14.1. The library is in Boost format and is intended to be placed in libs/mp11 in a Git clone of Boost. There is documentation in doc/html/mp11.html, it can be viewed locally, or with https://htmlpreview.github.io/?https://github.com/pdimov/mp11/master/doc/ht… Please excuse the lack of .css in that link. Thanks in advance for any interest, comments or suggestions.

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[safe_numerics] review results
by Andrzej Krzemienski 19 Mar '17

19 Mar '17

Hi Everyone, This is to inform you that safe_numerics library by Robert Ramey is *CONDITIONALLY ACCEPTED* to Boost. The list of conditions can be found down below. I would like to congratulate Robert for getting the library into Boost, and thank him for the effort to develop a useful library for the community. I also would like to thank everyone who participated in the review and shared their useful feedback. I recorded five reviews with a yes/no vote: - Paul A. Bristow (yes with conditions) - Steven Watanabe (yes with conditions) - John Maddock (yes with conditions) - Antony Polukhin (yes) - Barrett Adair (yes) And three without a vote: - Vicente J. Botet Escriba - John McFarlane - Peter Dimov We also got some feedback from an individual nicknamed "scatters" at Reddit (https://www.reddit.com/r/cpp/comments/5x1z67/boostsafe_ numerics_formal_review_starts_today/deew1kq/), and from Tomasz Kaminski in private conversation. There was a general consensus that the problem of surprises with C++ ints deserves a solution. Some people observed that there are other ways to approach the same problem, but it was agreed that the approach taken by safe_numerics is sound. The acceptance conditions mostly revolve around documenting micro-decisions made by the library, and fixing bugs. They apply to the reviewed GIT commit 3bcfabe1cafb8ef6edf08d3bd8730a1555b1c45d, but I know Robert is already working on fixing them, and has most of them fixed locally. *Acceptance conditions:* - Comply with Boost formal requirements: 1. index.html in root directory that redirects to doc/. 2. all headers in folder include/boost/numeric/. 3. Macro safe_literal: either remove it or let it follow Boost macro naming conventions: BOOST_NUMERIC_SAFE_LITERAL(). - Automatic promotion policy: either just remove it, or fix it so that: - it can see the range of safe_base in order to allow for slower increase in sizeof(), - it is clear from documentation how the promotion mechanism works. - in particular, what type gets selected for bit-wise operators &, | - The division bug (see below) is fixed. - Decide and document up front how the library addresses each of the following different situations: - overflow upon arithmetical operation, - unexpected promotion to unsigned when comparing signed with unsigned number, - arithmetic operation on unsigned int with negative value versus a signed value (-1 + 1u). - bit-wise operation on negative signed integers (unless they are removed), or that would produce one as the result. - division by zero, - operations upon default-constructed int type with indeterminate value, - conversion from float to int, when float contains non-integral value. - conversion from float to int, when float contains an integral value that would overflow upon native conversion - operator% where one operand is negative (for native ints it is implementaiton-defined) - leftshift by 32 bits (on 32-bit int) - Decide and document what safe's default constructor does. - Document upon which operations safe<> throws exceptions (or, signals arithmetic error at run-time). IOW, document in which cases safe<> never throws exceptions (signals run-time failure) because it is able to say that the operation will always succeed. - Document what happens when you invoke an operation on two instances of safe<> with different policies. - Resolve name conflict with interval, which already exists in namespace boost::numeric::interval. Either use a different namespace or a different name. - Remove anonymous namespaces from the header files. Use namespace detail and inline functions instead. - Improve test cases, so that they also check if numeric values of computations are correct (not only whether an operation throws or not). - Use enable_if (or similar) tricks to constrain the overload resolution for your arithmetical operations, so that they only work for numeric types rather than "any type T". - Fix the division bug: safe<signed, automatic> a {-1}; safe<unsigned, automatic> b {2}; auto c = a / b; // this returns 2147483647 <%28214%29%20748-3647> - Either document that safe<T> only works for scalar types (rather than any T that models concept Integer<T>), or provide alternate implementation of safe_base, as described in https://github.com/robertramey /safe_numerics/issues/44 - Fix linker errors when building a program from two cpp files that include safe_numerics headers. The error is caused by non-inline full specializations of operator<<. - Either entirely remove the support for bit-wise ops on signed types (make it a compiler error), or provide a consistent implementation that detects any UB or surprising results. - `++i` should return by reference; `i--` should return by value. *Other important issues* The following are *not *conditions for library acceptance, but I still recommend addressing them before the initial release. - Concepts: what do you need them for? Any other type except built-in scalars does not work anyway. Do you want to show how close safe<T> resembles T? In this case, they need to be changed. If you want to extend safe<T> to other T's, they need to be fixed: https://github.com/robertramey/safe_numerics/issues/46 <https://github.com/robertramey/safe_numerics/issues/46> - IOStreams interoperability needs fixes: - Move to a separate header, so that it does not affect compilation times when not needed (but provide forward declarations, so that implicit conversions to int do not make IOStreams work with unintended semantics) - Fix other problems as per https://github.com/robertramey /safe_numerics/pull/35 - safe<>'s interface is not documented - Make the library compile with -fno-exceptions: https://github.com/robertramey/safe_numerics/pull/31 <https://github.com/robertramey/safe_numerics/pull/31> - Some people fail to see how this library is better than just using rar ints but compiling with a UB-sanitizer. Address this in the documentation. - Prevent inadvertent ADL by putting safe into a nested namespace boost::numeric::save_types, and then in boost::numeric import: `using boost::numeric::save_types::safe`. This way boost::numeric::safe still works, but inadvertent ADL of everything inside namespace boost::numeric is prevented. - Does it make sense to apply bitwise operations on two different types? If so, document the semantics. - Fix header names and paths in documentation. - Consider adding support for saturation policy upon overflow. - Expression `safe<int>{4} ^ 1` does not compile due to overload resolution ambiguity. - Fix constexpr usages. - If possible, make workarounds in order to make the library work with MSVC. - Document that operations on safe<> do not thorw exceptions other than these thrown by exception policy. *Suggestions* The following summarizes other useful suggestions for improving the library in the future. - operation `safe<signed>{INT_MIN} + safe<unsigned>{UINT_MAX}` throws even though the mathematical result would fit in either signed or unsigned int. This is correct according to what policies describe, but is at the same time surprising, given that comparison `safe<signed>{INT_MIN} < safe<unsigned>{UINT_MAX}` just gives a mathematically correct answer rather than throwing an exception. Document this behavior explicitly. - Remove underflow_error from the policies: it sends the wrong message, that som form of an underflow is checked in this library. - Expose functions like add(), divide() in public interface, they might be useful on their own. - Expose the constructor with check disabled in the public interface, like `safe<int>{1, checks_sisabled{}}` this helps to locally disable the checks where the user knows that certain chain of operaitons will not overflow, and checks are redundant, but the library cannot see it. - Issues reported with bit-shift operators - unary operator- on unsigned type with pormotion policy `automatic` could return a signed type. - Use BOOST_NORETURN wherever possible, e.g. in throwing policies. - Use BOOST_LIKELY, BOOST_UNLIKELY for the policy tests. - Add support for statful policies. - Maybe drop the support for automatic type widening, to simplify the interface and the scope of the library, and let some other library handle the widening, maybe BigInt. Regards, Andrzej Krzemienski

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[release] 1.64.0 Decision on VS2017 version number?
by Rene Rivera 19 Mar '17

19 Mar '17

> (B) The community decides what version number we should be using and the > appropriate PRs are filed and applied and tested for all the repos > involved. Which means: > 1. The community has until 12:00 CDT US March 18 to decide on what the vc > version number and tag should be. > It's now past that time.. Is there consensus on what version number Boost should use for identifying the VS2017 toolset? If there is.. People need to start submitting PRs for the changes ASAP.. > 2. The community must post PRs for the places where we reference VS2017 > version numbers to the new number. Those are at least: > <https://github.com/boostorg/config> > <https://github.com/boostorg/build> > <https://github.com/boostorg/boost> > <https://github.com/boostorg/website> > People have until 17:00 CDT Monday March 20 to submit those PRs. Thanks. -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

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Project R-tree Serialisation
by Kabir Sahni 19 Mar '17

19 Mar '17

Hi everyone, I am midway through my competency test.I wanted to know whether working of serialisatjon for n dimensional point is the only thing to be demonstrated in main.cpp file. Thanks

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Re: [boost] Advanced find() for associative containers
by Bjorn Reese 19 Mar '17

19 Mar '17

On 03/16/2017 06:18 PM, Boris Rasin via Boost wrote: > 2. Where exactly should it fit in the boost? The most appropriate place would be Boost.Algorithm, so that is Marshall's domain. > Public interface consists of a single free function template: > > template <typename C> > auto find(C& c, const typename C::key_type& key); Your find() function deviates on several accounts from std::find() so it should probably be renamed, e.g. to find_key. Can you elaborate on why you have a specialization that uses lower_bound()? What is the minimal C++ version required? Looks like C++14 from the auto return type.

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Visual Studio multi-toolset support (was: [release] 1.64.0 please test master snapshot)
by Mateusz Loskot 18 Mar '17

18 Mar '17

On 18 March 2017 at 14:27, Peter Dimov via Boost <boost(a)lists.boost.org> wrote: > Mateusz Loskot wrote: > >>> No, VS 2015 can build with v140, v120, v110, v100, v90, as long as you >>> have the earlier versions installed. (VS 2017 can build with v140 even if >>> you don't have VS 2015 installed.) >> >> >> I understood VS2017 is first version with multi-toolset support. > > > The first version with multi-toolset support is VS 2012, although the only > two toolsets supported are v110 and v110_xp, which share the same version. > VS 2013 supports v90 - v120. VS 2015 supports v90 - v140. I always used the 'default' toolset of particular VS version, hence fostered ignorance about that multi-toolset support. > Wait, no, VS 2010 supports v100 and v90. :-) :-) Thank you for the enlightenment. Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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[release] 1.64.0 please test master snapshot..
by Rene Rivera 18 Mar '17

18 Mar '17

After help from various sources to get the VS2017 building working the latest master snapshot should at least try and build with VS2017. Assuming nothing horrible shows up today we will release the first beta tonight. Hence, please smoke test the latest master snapshot found at: <https://dl.bintray.com/boostorg/master/> -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

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[review process] candidate library maintenance disturbs the review
by Andrzej Krzemienski 17 Mar '17

17 Mar '17

Hi Everyone, In the context of the discussion around review process improvements, I wanted to report another problem that I do not know how to solve. But maybe you do. Extending the review period by allowing the review on the BLIncubator looks like a good idea, but it also comes with a problem. The review applies to a particular commit (if we use GItHub terms), that is, to the state of the library on a particular branch at a particular point in time. If I see a review on BLIncubator (not that I see many of them), how do I know what commit it applies to and if it is even irrelevant. It might be partially relevant, but it puts me in an uncomfortable situation, that I will be investing my time in something that is likely to turn out to be useless. Also, I might consider submitting a review into BLIncubator, but what chances I have that it will be considered in the formal review, given that the formal review may work on a different commit: possibly on a quite different library by now? Regards, &rzej;

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[gsoc2017] Apply for static_map
by Dobra Gábor 17 Mar '17

17 Mar '17

Hi all, I'm planning to participate to Boost GSOC, about static_map proposal. I'm Gábor Dobra, third-year student of Budapest University of Technology, Hungary, software engineering BSc. I've contributed to a few open-source libraries, I'm working as a C++ developer at a finance company. I'd like to contact a mentor of static_map (possibly Niall Douglas?) about my competency test. Thanks, Gábor

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