March 2020 - Boost - lists.preview.boost.org

[gil] Review of move assignment operator for image class
by Mateusz Loskot 02 Apr '20

02 Apr '20

Hi, We're adding move semantics to some of GIL classes [1] and we'd like to receive feedback on the move-assignment operator for the image class [2] (copied below) that we've worked out so far if there are any major blunders to correct or gaps to fill for C++11 compliant implementation: image& operator=(image&& img) { if (this == std::addressof(img)) return *this; auto const exchange_memory = [](image& lhs, image& rhs) { lhs._memory = boost::exchange(rhs._memory, nullptr); lhs._align_in_bytes = boost::exchange(rhs._align_in_bytes, 0); lhs._allocated_bytes = boost::exchange(rhs._allocated_bytes, 0); lhs._view = boost::exchange(rhs._view, image::view_t{}); }; constexpr bool pocma = std::allocator_traits<Alloc>::propagate_on_container_move_assignment::value; if (pocma) { // non-sticky allocator, can adopt the memory, fast destruct_pixels(this->_view); this->deallocate(); this->_alloc = img._alloc; exchange_memory(*this, img); } else if (_alloc == img._alloc) { // allocator stuck to the rhs, but it's equivalent of ours, we can still adopt the memory destruct_pixels(_view); this->deallocate(); exchange_memory(*this, img); } else { // cannot propagate the allocator and cannot adopt the memory if (img._memory) { allocate_and_copy(img.dimensions(), img._view); destruct_pixels(img._view); img.deallocate(); img._view = image::view_t{}; } else { destruct_pixels(this->_view); this->deallocate(); this->_view = view_t{}; } } return *this; } One thing that is still missing is the noexcept with expression evaluated based on something like this template <class _Alloc> using is_noexcept = std::conditional_t < std::allocator_traits<_Alloc>::is_always_equal::value, _Equal_allocators, typename std::allocator_traits<_Alloc>::propagate_on_container_move_assignment::type >; but we there is no is_always_equal in C++11, so there are gaps to fill. Any comments are appreciated. [1] https://github.com/boostorg/gil/pull/457/ [2] https://github.com/boostorg/gil/blob/7d8df1c105e81070e30ef68ea7abb8e39111d6… Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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Request to review my GSoc Proposal[Boost multiprecision
by suyashtava 01 Apr '20

01 Apr '20

Dear Sir/Ma'am, It would be great if you could review my GSOC proposal for [Boost multiprecision]: New Big-Double Backend Types Doc link: https://docs.google.com/document/d/1xznSxg1XcAiQMnVXSMG_NwxuUeGmkI5iXhabSXe… I deeply regret and apologize for the late submission, but I request you to review it once as it will surely help me to update it in required ways. With regards Suyash Srivastava IIT(ISM) Dhanbad -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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[GSoC2020][Boost.Real] Greeting
by Firmin Martin 01 Apr '20

01 Apr '20

Hi, Boost community! This mail is not intended to serve as a proposal review (it's too late obviously). Instead, I would want to greet my potential mentors and possible collaborators. Anyway, whether or not my proposal is retained, I will probably still contribute after GSoC 2020 since I've got familiar enough to the codebase by dint of reading blog posts, references and code sources. I made a small PR involving BBP formula to compute the n-th binary digit of pi and already submitted my final proposal to GSoC. Best regards, Firmin

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Download links all broken?
by John Maddock 31 Mar '20

31 Mar '20

All the download links from www.boost.org appear to be currently broken - which is to say no one can download Boost right now. Ideas or fixes anyone? Thanks, John. -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

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[test][program_options] Avoid deprecated bind placeholders in global namespace
by Mateusz Loskot 31 Mar '20

31 Mar '20

Hi, I have a shy request to maintainers of boostorg/test and boostorg/program_options Would it be possible to merge these trivial patch to both: https://github.com/boostorg/test/pull/259 https://github.com/boostorg/program_options/pull/92 Thanks in advance. Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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Proposal Review
by Kishan shukla 31 Mar '20

31 Mar '20

Hello everyone, I have prepared the draft proposal for the boost.Real project. It involves adding new mathematical functions and operators into the library. I have also planned on optimizing a few algorithms and addressing previously unresolved issues. The proposal is the result of my discussion with my mentor Damian Vicino. Sorry for being late. Please review the proposal and provide your valuable feedback. Proposal link: https://docs.google.com/document/d/1oXAaaiqgtC2bTCfADPwXUY4ItYw-C8EMOLr2Bhu… Regards, Kishan Shukla

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GSoC 2020
by Sachin Saw 31 Mar '20

31 Mar '20

Dear Developers, I am Sachin, a third year undergraduate student at Indian Institute of Technology Kharagpur, I have been using C++ for around three years and have a good experience in it. I like to contribute to boost on Boost.Geometry during GSoC’20. I went through https://www.iis.sinica.edu.tw/page/jise/2012/201205_10.pdf and found a great explanation of algorithm during GSoC period I would like to work on above algorithm (in the link) and concave hull using k-nearest neighbours approach so that one would act as a test for other. If would love to have suggestion from you Thanks,

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[gsoc20] Proposal review for Boost.Real
by Vikram Chundawat 31 Mar '20

31 Mar '20

Hello everyone, I have prepared my draft proposal for Boost.Real project on improving the base, adding new number types and adding a method to calculate powers. Here is the link to the proposal https://docs.google.com/document/d/10Hy87Ok7UTzqPvzD35BkrlL-Sx4G8HfSCzchwYa… I have been in touch with this project's potential mentor Damian Vicino and this proposal is the result of my discussion with him. Please kindly provide your valuable feedback on the proposal. Thank you Regards Vikram Singh Chundawat

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[gsoc20]Proposal for general robust predicates for Boost.Geometry
by Tinko Bartels 30 Mar '20

30 Mar '20

Hello Boost-Community, I have prepared a draft proposal for general robust predicates for Boost.Geometry. The ideas are described in more detail in the proposal, but I will briefly describe them here: A number of geometric algorithms, such as the triangulation of a point set, employ geometric predicates (implemented as strategies in Boost.Geometry). One example for such a predicate is the 2d orientation test, which, given three points p1, p2, p3, determines whether p3 lies on the left or right side of the line segment that goes through p1 and p2. Using floating-point arithmetics to answer that question can lead to incorrect and ultimately inconsistent results that may cause the algorithm that employs the predicate to produce nonsensical results or crash entirely for certain inputs. Using algorithms for exact floating-point arithmetics combined with some considerations regarding forward error analysis, a complicated method can be implemented that evaluates such predicates robustly and only adaptively increases the precision if necessary to avoid expensive high precision computations whenever possible. I propose a general, automated approach that generates such robust, adaptive predicates from arbitrary arithmetic expressions. Currently, Boost.Geometry has robust adaptive predicates for the 2d orientation and the 2d incircle test. This work would enable us to easily extend this to 3d orientation, 3d insphere, and generally all predicates that can be evaluated by determining the sign of a polynomial. I want to present my proposal for review publicly now: https://docs.google.com/document/d/19zH9QuSSNWAHm1DP5poxbRxcMXlzRVWfL5Wslbe… Kind regards Tinko Bartels -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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[cmake][array][vs] Trying develop and test a single library
by Mateusz Loskot 30 Mar '20

30 Mar '20

Hi, I'm learning about the boostorg/cmake infrastructure offered by Peter. I picked Boost.Array as a library with simple build setup. I replaced the existing (hand-rolled?) CMakeLists.txt files with the generated ones: b2 tools\boostdep\build dist\bin\boostdep.exe --cmake array Then, learning form boostorg/cmake itself how to use it https://github.com/boostorg/cmake/blob/develop/.travis.yml#L228 cd BOOST_ROOT mkdir __build__ && cd __build__ cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=ON -DBOOST_INCLUDE_LIBRARIES=array .. cmake --build . ctest --output-on-failure -R boost_array Visual Studio solution is nicely generated, all expected .vcxproj files too, but, AFAICT, neither the last two commands nor these do anything: cmake --build . --config Release cmake --build . --config Debug I loaded the Boost.sln in VS 2019 and Build > Build Solution worked. I also noticed this 'unusual' project-as-target called check. I'm back in the CLI mode and run: cmake --build . --target check this time all the tests build and run. Interestingly, if I feed the ctest with the build configuration, then it also builds the tests, and runs them too, of course: ctest --output-on-failure -R boost_array -C Release ctest --output-on-failure -R boost_array -C Debug Is this `cmake --build .` doing nothing specific Boost.CMake? Is that `check` target supposed to be used explicitly? Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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