March 2021 - Boost - lists.boost.org

Confusion regarding projects
by Ameya Chawla 17 Mar '21

17 Mar '21

Respected sir/madam I want to contribute to Boost C++ libraries , but i am confused that do I have to contribute to all the 3 projects mentioned in Boost.uBlas <https://github.com/boostorg/ublas>: Matrix and Tensor Computations or I can contribute to any one of them .and competency test is for project 2 only or for all 3 projects ? https://github.com/CGAL/cgal/wiki/Project-Ideas Thank you

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Confusion regarding projects
by Ameya Chawla 17 Mar '21

17 Mar '21

Respected sir/madam I want to contribute to Boost C++ libraries , but i am confused that do I have to contribute to all the 3 projects mentioned or I can contribute to any one of them .and competency test is for project 2 only or for all 3 projects ? https://github.com/CGAL/cgal/wiki/Project-Ideas Thank you

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[release] Boost 1.76.0 beta 1 released
by Marshall Clow 16 Mar '21

16 Mar '21

Boost release 1.76.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.76.0.beta1/source/> The SHA256 checksums are as follows: 39eecd9672e78b95c8e3fdec1430a63788d528a66d3c8799c4639238e5d785bd boost_1_76_0_b1.7z c32edd34f767dd4bb67b86f76ebf58cf76822a5993a9b434c028b2dd08cfeefc boost_1_76_0_b1.zip 3ec1f92fa0a159b7073e39dd88f527a55d1f35e8986a3c560f202a75bdb8d584 boost_1_76_0_b1.tar.gz eb098d6d5352e10b17a3c49d2927ed61f09b6544f7c534627de35dfa2560fe20 boost_1_76_0_b1.tar.bz2 For details of what's in the release, see <https://www.boost.org/users/history/version_1_76_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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Introduction-Tushar Khandelwal
by Tushar k 16 Mar '21

16 Mar '21

Hi, I am Tushar Khandelwal from BITS Pilani 2019 Batch, I have a decent understanding of C++, I have been practicing C++ for the past 2 years, I am proficient in data structures and algorithms, I am new to open source and would love to contribute to this organization. How should I get started?

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Headers only or .o
by Damian Vicino 15 Mar '21

15 Mar '21

Hi, I was reading the development section of the docs: https://www.boost.org/development/index.html And, I noticed there was nothing in the development guidelines about when to implement as headers-only vs built library. I got my own ideas of why most libraries are headers-only. But, I was wondering if someone with the historical context (someone who was here when those first libraries were developed) can share how boost got into the current shape and what new library developers should look into when deciding to go headers-only or not. I appreciate any anecdotes, guidelines, tradeoffs, thumb rules, comments on the topic. I would love to collect as much as possible here in this thread and write something to post in the development doc section in the website for future reference. Best, Damian

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[Describe] Review - Part 2: Class types
by Andrzej Krzemienski 15 Mar '21

15 Mar '21

Hi Everyone, Some feedback from playing with Boost.Describe for class types. 1. As others pointed out, it is confusing that BOOST_DESCRIBE_STRUCT() and BOOST_DESCRIBE_CLASS() have such close names, but their interface and requirements are so different. Maybe rename the latter to BOOST_DESCRIBE_THIS_CLASS()? 2. Base class subobjects are in some applications treated equivalently to member subobject; this is why I found it surprising that I cannot get the names of base class subobjects. But I guess there are implementation difficulties. Bases can be qualified names. 3. As with enums, _public_member_descriptor_fn in global namespace is UB or invalid program as per http://eel.is/c++draft/lex.name#3.2. 4. As others pointed out, the part of the interface that uses enum modifiers is not intuitive. I think that after a while it starts to make sense: you decide on your use case (like doing RPC), form your enum bitmask, and then pass it everywhere. It became more-less clear to me only after I had a look at the implementation of member_filter: https://github.com/pdimov/describe/blob/develop/include/boost/describe/memb… Maybe it makes sense to expose this in the docs. 5. Modifier mod_inherited is great for flattening the inheritance structure: struct X { int a; }; struct Y : X { int b; }; struct Z : Y { int c; }; BOOST_DESCRIBE_STRUCT(X, (), (a)); BOOST_DESCRIBE_STRUCT(Y, (X), (b)); BOOST_DESCRIBE_STRUCT(Z, (Y), (c)); int main() { namespace desc = boost::describe; using namespace std::literals::string_literals; constexpr auto mod = static_cast<desc::modifiers>(desc::mod_public | desc::mod_inherited); using L = desc::describe_members<Z, mod>; assert((boost::mp11::mp_at_c<L, 0>::name == "a"s)); assert((boost::mp11::mp_at_c<L, 1>::name == "b"s)); assert((boost::mp11::mp_at_c<L, 2>::name == "c"s)); } But it is not obvious at first. I recommend that the docs provide an example like this. It even works when base classes have members with same names: struct X { int a; }; struct Y { int a; }; struct Z : X, Y { int b; }; BOOST_DESCRIBE_STRUCT(X, (), (a)); BOOST_DESCRIBE_STRUCT(Y, (), (a)); BOOST_DESCRIBE_STRUCT(Z, (X, Y), (b)); int main() { constexpr auto mod = static_cast<describe::modifiers>(describe::mod_public | describe::mod_inherited); using L = describe::describe_members<Z, mod>; Z z = {{{3}}, {{6}}, {9}}; assert((z.*mp_at_c<L, 0>::pointer == 3)); assert((z.*mp_at_c<L, 1>::pointer == 6)); assert((z.*mp_at_c<L, 2>::pointer == 9)); } 5. What is the use case for modifier mod_hidden? I cannot think of any situation where I would need it. 6. Regarding the overloaded functions, I am no expert in preprocessor metaprogramming, but maybe if there was a way to provide function signatures along the name, you would have enough information to form the pointers. Something like: struct X { void f(int){} void f(void*){} }; BOOST_DESCRIBE_STRUCT(X, (), ( SIGNATURE(void f(int)), SIGNATURE(void f(void*)) ); 7. Modifier mod_virtual works unintuitively. It does not affect the filtering in describe_bases<>. It is only used for decorating the list elements. Maybe the docs should be more explicit about what it is used for. Again, is there a use case for this? Regards, &rzej;

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GSoC'21 boostorg timeline
by Krushnal Patel 15 Mar '21

15 Mar '21

Hi, I wanted to inquire about the GSoC'21 timeline specific to boostorg. I have gone over the GSoC'21 timeline but are there any specifics decided by boost regarding project selection, pre-proposal submission, proposal overview, programming competency test submission, etc? I am asking this question because as I was going over last years' mailing list I found a post where 'pre-proposal submission' was discussed so I started researching more about any timeline released specifically by boost but did not find any. Thanks in advance. Krushnal Patel, http://krushnal.me/

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Requirement of mentorship for Generic Image Library project
by Aditya Tiwari 15 Mar '21

15 Mar '21

Hello there, I am Aditya Tiwari, a GSoC aspirant. I am interested in contributing to the Boost C++ library on the project "*Generic Image Library*". The knowledge requirement for this project is C++ and understanding of basic image processing algorithms, and I have a good knowledge of these two. I have been coding in C++ for over two years, with prior experience working with Boost libraries and working on projects related to image processing for over 1 year. I have read the problem statement and under GIL there's a project 2 about implementing image processing algorithms and in that list I know quite a bunch of algorithms. Also the project 1 under GIL, is quite a confusing task for me like do we have to add more and efficient algorithms here or something else? It would be very helpful if you can guide me through this project. I am open to any suggestions and I shall proceed with the task upon your acknowledgement. Regards, Aditya

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Re: [boost] [release] Boost 1.76.0 Beta 1 Release Candidate 1: fixed std::allocator deprecation-warning
by Löw, Tobias (STEAG Energy Services GmbH) 15 Mar '21

15 Mar '21

Hi, I've made a fix for the deprecation-warning: boost\unordered\detail\implementation.hpp(1452,7): warning C4996: 'std::allocator<T>::is_always_equal': warning STL4010: Various members of std::allocator are deprecated in C++17. Use std::allocator_traits instead of accessing these members directly. You can define _SILENCE_CXX17_OLD_ALLOCATOR_MEMBERS_DEPRECATION_WARNING or _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS to acknowledge that you have received this warning. The PR is here: https://github.com/boostorg/unordered/pull/21 Tobias

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[release] Boost 1.76.0 Beta 1 Release Candidate 2
by Marshall Clow 13 Mar '21

13 Mar '21

The second release candidates for the 1.76.0 beta release are now available at: <https://dl.bintray.com/boostorg/beta/1.76.0.beta1/source/> The SHA256 checksums are as follows: c32edd34f767dd4bb67b86f76ebf58cf76822a5993a9b434c028b2dd08cfeefc boost_1_76_0_b1_rc2.zip eb098d6d5352e10b17a3c49d2927ed61f09b6544f7c534627de35dfa2560fe20 boost_1_76_0_b1_rc2.tar.bz2 39eecd9672e78b95c8e3fdec1430a63788d528a66d3c8799c4639238e5d785bd boost_1_76_0_b1_rc2.7z 3ec1f92fa0a159b7073e39dd88f527a55d1f35e8986a3c560f202a75bdb8d584 boost_1_76_0_b1_rc2.tar.gz The only changes from RC1 is an update to Boost.Interprocess, which was failing to compile on Mac OS X. As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Release managers

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Master branch now closed for 1.76.0 beta release
by Marshall Clow 13 Mar '21

13 Mar '21

Please do not make any commits to the master branch. — Marshall

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Re: [boost] FFT proposal for gsoc 2021
by Janek Kozicki 13 Mar '21

13 Mar '21

> Strongly and beneficially Influence that. But we still need > To adhere to all formal application Steps A note regarding these formal steps: https://github.com/boostorg/wiki/wiki/Google-Summer-of-Code%3A-2021 https://lists.boost.org/Archives/boost/2021/02/250876.php https://www.boost.org/users/faq.html > On the board. I can do 1 mentor of Either quad double or FFT. Yeah, both of them are very useful for me. If we make FFT this year, we can hope for quad-double next year :-) best regards Janek Christopher Kormanyos said: (by the date of Fri, 12 Mar 2021 16:00:38 +0100) > We still need to adhere to the > Formal application process > And we should have our dialog > On the board. I can do 1 mentor of > Either quad double or FFT. > > Having your own idea and a > Working model is a tremendous > Advantage in the application > Process and is likely to very > Strongly and beneficially > Influence that. But we still need > To adhere to all formal application > Steps > > Kindest regards, Chris > > Sent from my iPhone > > > On 12. Mar 2021, at 07:26, Eduardo Quintana <eduardo.quintana(a)pm.me> wrote: > > > > Dear Christopher, > > > > I am thrilled to hear from you! Thank you for offering mentorship for this > > project. I look forward to start working on it. > > > > Best regards, > > Eduardo > > > >> On Thu, Mar 11, 2021 at 06:55:37PM +0000, Christopher Kormanyos wrote: > >> > >> <html><head></head><body><div class="ydpad5c413ayahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><div></div> > >> <div dir="ltr" data-setdir="false"><div>> Hi Boost community,<br><div>> I've been working on a C++ templated library</div><div>> for Fast Fourier Transforms</div><div><br></div><div>> ...<br></div></div><div dir="ltr" data-setdir="false"><span>> Is there anyone interested in supervising this</span></div><div dir="ltr" data-setdir="false"><span>> project? Any opinions?</span></div><div dir="ltr" data-setdir="false"><span><br></span></div><div dir="ltr" data-setdir="false"><span>Thank you for your interest and query.<br></span></div><div dir="ltr" data-setdir="false"><span><br></span></div><div dir="ltr" data-setdir="false"><span>Yes. I think I am interested and potentially qualified</span></div><div dir="ltr" data-setdir="false"><span>as 5 time GSoC mentor in Multiprecision and Math.</span></div><div dir="ltr" data-setdir="false"><span><br></span></div><div dir="ltr" data-setdir="false"><span>The plan seems good, start with header only</span></div><div dir="ltr" data-setdir="false"><span>simple implementation and increase complexity</span></div><div dir="ltr" data-setdir="false"><span>and efficiency as time allows.</span></div><div dir="ltr" data-setdir="false"><span><br></span></div><div dir="ltr" data-setdir="false"><span>This project would fill a present gap and wish list</span></div><div dir="ltr" data-setdir="false"><span>entry in Math/Multirpecision for those unable/unwilling</span></div><div dir="ltr" data-setdir="false"><span>to include FFTW.</span></div><div dir="ltr" data-setdir="false"><span><br></span></div><div dir="ltr" data-setdir="false"><span>I will write a little project description at rthe relevant</span></div><div dir="ltr" data-setdir="false"><span>page, link will follow...<br></span></div><div dir="ltr" data-setdir="false"><span><br></span></div><div dir="ltr" data-setdir="false"><span>Feel free to continue this thread, at the moment, i'm</span></div><div dir="ltr" data-setdir="false"><span>too busy to put down all my thoughts...<br></span></div><div dir="ltr" data-setdir="false"><span><br></span></div><div dir="ltr" data-setdir="false"><span>Kind regards, Christopher</span><br></div></div><div><br></div> > >> > >> </div><div id="yahoo_quoted_5520563993" class="yahoo_quoted"> > >> <div style="font-family:'Helvetica Neue', Helvetica, Arial, sans-serif;font-size:13px;color:#26282a;"> > >> > >> <div> > >> On Thursday, March 11, 2021, 10:55:29 AM GMT+1, Eduardo Quintana via Boost <boost(a)lists.boost.org> wrote: > >> </div> > >> <div><br></div> > >> <div><br></div> > >> <div>Hi Boost community,<br><br>I've been working on a C++ templated library for Fast Fourier Transforms,<br>https://github.com/Lagrang3/fftx.<br>Templated because some FFT algorithms are algebraic-field independent, eg. you<br>could FFT an array of N matrices provided a Nth matrix-root-of-unity is given.<br>As a result you could have a single algorithm for a variety of underlying, eg.<br>`std::complex<float>`, `std::complex<double>`, `std::complex<long double>`,<br>`boost::math::quaternion`, finite field types (this would yield the "Number<br>theoretic transform" <a href="https://cp-algorithms.com/algebra/fft.html#toc-tgt-6" target="_blank">https://cp-algorithms.com/algebra/fft.html#toc-tgt-6</a>).<br><br>I would like to improve this library during the GSOC 2021, as a proposal for<br>inclusion inside Boost.Math or Boost.Algorithms.<br><br>Is there anyone interested in supervising this project? Any opinions?<br><br>Best regards,<br>Eduardo Quintana<br><br>_______________________________________________<br>Unsubscribe & other changes: <a href="http://lists.boost.org/mailman/listinfo.cgi/boost" target="_blank">http://lists.boost.org/mailman/listinfo.cgi/boost</a><br></div> > >> </div> > >> </div></body></html> > > <publickey - eduardo.quintana(a)pm.me - 341e5416.asc> > -- -- Janek Kozicki, PhD. DSc. Arch. Assoc. Prof. Gdańsk University of Technology Faculty of Applied Physics and Mathematics Department of Theoretical Physics and Quantum Information -- http://yade-dem.org/ http://pg.edu.pl/jkozicki (click English flag on top right)

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[GIL] 2D Convolution/Correlation Proposal for gsoc 2021
by Gaurav kumar 12 Mar '21

12 Mar '21

Hi, I am Gaurav Kumar; I have been working on the Boost.GIL library for the past month. I would like to work on the 2D convolution/Correlation project. The ideas for the project are as follows: 1. Separable Kernels <http://www.dspguide.com/ch24/3.htm>: Most of the standard kernels (e.g. Gaussian, Sobel) can be separated into 2 or more 1D filters. For a N x N kernel, separating it into two 1D filters, the number of computations required would now be proportional to 2*N instead of N*N for the naive implementation. This implementation would also favor code reusability as this would only require a kernel separating function and driver code for a group of 1D filters. 2. Generic Implementation for 2D convolution: There are more generic kernels that are non-separable (e.g. Laplacian operator). In this case, the naive approach has already been implemented. The main task would be to provide the same set of functions as in the 1D convolution/correlation implementation. One potential idea for optimization of 2D convolution is to use the Im2col <https://www.programmersought.com/article/6306124604/> operation, in which the input image is converted into a row of column vectors, where each column vector represents an image block for which convolution/correlation operation is to be performed. The kernel can also be flattened out in a similar manner, resulting in a 1D array. This results in the convolution operation being reduced to matrix multiplication, which can be handled efficiently by BLAS libraries <https://en.wikipedia.org/wiki/Basic_Linear_Algebra_Subprograms> ( Boost.uBLAS ). Please share any suggestions you would have, related to the ideas presented above, or regarding 2D convolutions in general. I am looking for a mentor to guide me through this project. Best Regards, Gaurav Kumar Github handle: https://github.com/gkumar28

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[release] Boost 1.76.0 Beta 1 Release Candidate 1
by Marshall Clow 12 Mar '21

12 Mar '21

The first release candidates for the 1.76.0 beta release are now available at: <https://dl.bintray.com/boostorg/beta/1.76.0.beta1/source/> The SHA256 checksums are as follows: a222d325cd3c9f66951ec9026eca6ff6f48dd563c9a025911d598d2aca8770ce boost_1_76_0_b1_rc1.tar.bz2 6b90b510a3de38fc30a071ac798da37545fb60a1d6b21aed1130b47c9c598977 boost_1_76_0_b1_rc1.zip b01627bd9ce934b092037da81696bb4482a44e6a31c8791dbed82eafe04b69fa boost_1_76_0_b1_rc1.tar.gz dbef57adbab1d4395d14000f0a2420fc82f87476e10d48359ceff7125a74b77a boost_1_76_0_b1_rc1.7z As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Release managers

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Endorsement, review manager sought for Boost.Mysql
by Ruben Perez 12 Mar '21

12 Mar '21

Hi all, I would like to propose a MySQL client library for Boost (under the original name of Boost.Mysql). It is a full implementation of the MySQL client protocol, based on Boost.Asio. It requires C++11. The library is at https://github.com/anarthal/mysql and the documentation is at https://anarthal.github.io/mysql/. Examples under https://anarthal.github.io/mysql/mysql/examples.html. The purpose of this library is to provide a low-level building block for applications or other libraries to interact with MySQL, in the same way Boost.Beast provides a way to interact with HTTP. It complies with Boost.Asio universal asynchronous model, and provides the usual sync and async overloads for every network operation. Some notes: - The scope of this library is limited to MySQL. Its value proposition is implementing the client protocol in an Asio-compliant way. Supporting any database other than MySQL is not in scope of this library. - This library does NOT make use of MySQL libmysqlclient C API. It provides a from-the-ground-up implementation of the MySQL client protocol. Features: - Text queries and server-side prepared statements. - Sync and async functions, following Boost.Asio's universal async model. You may use callbacks, Boost coroutines, futures, C++20 coroutines, or any completion handler that Asio adds support for. - Can be used with any Stream including TCP sockets, UNIX sockets and Boost.Beast TCP streams. - Supports MySQL 5.x, MySQL 8.x and MariaDB.

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[Boost][Describe] Has been ACCEPTED into Boost
by Richard Hodges 12 Mar '21

12 Mar '21

Dear all, I am pleased to announce that we have received 13 high quality reviews. There has been no dissent, with every reviewer recommending that Describe be accepted. Reviews that were sent to me privately have been forward to Peter for consideration. If you have submitted a review and I have not responded privately to thank you, then please accept my apology for this oversight. Thank you everyone for taking some of your valuable time to contribute. -- Richard Hodges hodges.r(a)gmail.com office: +442032898513 home: +376841522 mobile: +376380212

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[interprocess][managed_shared_memory] Memory allocation of managed shared memories
by Grimm, Matthias 12 Mar '21

12 Mar '21

Hi, I have a question regarding the interprocess library and the use of shared memories. When creating a boost::interprocess::managed_shared_memory it seems to be necessary to take some additional space into account. In my case the following approach works well: managed_shm = new ip::managed_shared_memory(ip::create_only, "shm_id", (vec_elems + 110) * (number_of_samples + 1)); Following this it seems to be necessary to always have one additional element. If I remove the additional element (vec_elems + 110) * (number_of_samples) an exception is thrown: boost::interprocess::bad_alloc. This is also the case if I change to (vec_elems) * (number_of_samples + 1) Does anybody know why it is necessary to have this additional space allocated? What is the exact minimum size to avoid the exception? The additional memory may become a problem if the size of the vector elements is large. Attached you'll find some example code. Any help on this topic would be appreciated.

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GSoC'21
by Manan Sharma 12 Mar '21

12 Mar '21

Hey, My name is Manan Sharma, I went through the project ideas for the GSoC'21 and the Multiprecision project really caught my eye. So I would like to contribute to this project but do not know where to start. I have basic knowledge of C++ like Template Programming. So I would appreciate it if anyone could tell me how to get started. Looking forward to contributing to the project. Yours sincerely, Manan Sharma Phone No.: +91 9711306818 Email Id.: manan180796(a)gmail.com

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Queries regarding Contributing to boost open source library
by Tirtharaj Sen 12 Mar '21

12 Mar '21

Hello, I'm Tirtharaj Sen I wanted to know that I will start to contribute to boost open source library from today , so will can I make proposals for GSOC 2021 to the organisation or am I a bit late to start to contribute. I would also like to mention that I want to be associated with the organisation even after the GSOC is over. So does it require a 3 months of contribution history? Will be obliged if I get help from yours's side Thank you

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Does anyone use mp11 with VS2013?
by Peter Dimov 11 Mar '21

11 Mar '21

Does anyone here use mp11 with Visual Studio 2013? (msvc-12.0) 2013 kind of supports C++11 but only barely, and I keep bumping into its bugs and limitations, so I'm considering dropping it and making 2015 the minimum requirement.

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[Boost] [Describe] library submission - last call for reviews from the community
by Richard Hodges 11 Mar '21

11 Mar '21

A friendly reminder that the review period for [Boost.Describe] will finish at the end of tomorrow - 10th March 2021 We've had some excellent feedback already, and would value more. If you can spare a few hours of your valuable time, please consider reviewing this neat little library and posing your results on this mailing list. The invitation is repeated below: The Boost formal review of the Describe starts Monday, taking place from March 1st, 2021 to March 10th, 2021 (inclusive). The library is authored by Peter Dimov. Documentation: https://pdimov.github.io/describe/doc/html/describe.html Source: https://github.com/pdimov/describe The library provides a simple means of providing reflection for structures and enums in C++. The documentation contains a number of common motivating examples, including: - A universal print function https://pdimov.github.io/describe/doc/html/describe.html#example_print_func… - JSON serialisation https://pdimov.github.io/describe/doc/html/describe.html#example_to_json Please provide in your review information you think is valuable to understand your choice to ACCEPT or REJECT including Describe as a Boost library. Please be explicit about your decision (ACCEPT or REJECT). Some other questions you might want to consider answering: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With which compiler(s)? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? More information about the Boost Formal Review Process can be found at: http://www.boost.org/community/reviews.html The review is open to anyone who is prepared to put in the work of evaluating and reviewing the library. Prior experience in contributing to Boost reviews is not a requirement. Thank you for your efforts in the Boost community. They are very much appreciated. Richard Hodges - review manager of the proposed Boost.Describe library Peter is often available in the CppLang Slack #boost channel should you require any clarification not covered by the documentation, as am I. Please submit your review to the Boost mailing list: boost(a)lists.boost.org -- Richard Hodges hodges.r(a)gmail.com office: +442032898513 home: +376841522 mobile: +376380212

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[release] Reminder about 1.75.0 release notes
by Marshall Clow 11 Mar '21

11 Mar '21

The master branch is closing on Wednesday for the 1.75.0 release. If you have information that should go into the release notes, now’s the time to add it. Create a PR against https://github.com/boostorg/website/blob/master/feed/history/boost_1_75_0.q… <https://github.com/boostorg/website/blob/master/feed/history/boost_1_75_0.q…> — Marshall

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[release] Release notes for 1.76.0
by Marshall Clow 11 Mar '21

11 Mar '21

If you have information that should go into the release notes, now’s a good time to add it. Create a PR against https://github.com/boostorg/website/blob/master/feed/history/boost_1_76_0.q… — Marshall

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[Geometry] Proposing a project idea for GSOC 2021
by Siddharth Kumar 11 Mar '21

11 Mar '21

Hey, This is Siddharth Kumar. I have been working on the Boost.Geometry library for the past 2-3 months. I would like to propose a project idea about adding features for 3d-geometries, especially polyhedral surfaces which includes:- 1. Defining a geometry for the polyhedral surfaces. 2. Read and write features for the polyhedral surfaces. 3. Defining functions for the properties of polyhedral surfaces like volume, surface area, etc. This implementation will help in the direct use of the geometry in such algorithms, which are not yet implemented for the 3d-geometries or don’t provide compatible results when working with 3d-shapes, as they give points as an output rather than taking a geometry. For example- The convex hull <https://github.com/boostorg/geometry/issues/683> doesn’t handle 3d geometries correctly, because there is no 3d geometry defined that can handle the result of the algorithm. I have already submitted a PR <https://github.com/boostorg/geometry/pull/789> (yet to be merged), which defines the geometry for polyhedral surfaces, and also includes wkt read and write features, I am willing to work on other properties of the polyhedral surfaces as a project for GSOC 2021. I am looking for a mentor who is willing to guide me in this project. Thanks

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[Describe] Andrzej's review.
by Andrzej Krzemienski 10 Mar '21

10 Mar '21

Hi Everyone, This is my review of the Boost.Describe library. I recommend that the library should be **ACCEPTED** into Boost. The goal of the library is clearly specified, and addresses real world needs. The examples (JSON serialization, printing) are convincing, and the number of reviews saying "I needed it for a while" reassure that it will be useful. The library is well designed. I mean the separation into macros declaring the "reflection lsts", and then functions operating on those lists. The documentation, in connection with the clear design, makes it easy to learn and use the library. The only issues I had was with the modifiers enum: I had to look into the implementation to understand how some values work. Regarding the implementation, I only had a superficial look. One thing I observed is that the implementation is very short! When I tried to combine all headers into one, in order to test it on WandBox, I discovered that it is less than 600 lines. You can see it here: https://wandbox.org/permlink/rkAtPCbAsqNzVRMV The only issue I have is the names that start with the underscore that can potentially end up in the global namespace, which by my reading of the C++ Standard is UB. I have spent a couple of hours testing toy examples, reading the docs, and looking at the implementation. I used GCC 9.2.0 on MinGW and GCC 10.1.0 on WandBox. All worked fine. Regarding my previous concerns about the "N+1" problem (an overlap with other libraries), I no longer have it. Boost.Describe is for class and enum authors to offer a reflection information for whoever wants it. A library like Boost.Fusion is for working with fusion sequences. Only as convenience, it provides a way to adapt a user defined class as a fusion sequence, but if it wants, it can use Boost.Describe lists as an alternative way of providing the adaptation. My two real-life use cases for a reflection like this was: 1. Adapting aggregates for Boost.Spirit. It looks like even Boost.FPR would do. 2. Printing and implementing swap() and hash() for my types. So far I had to do it manually, so I am looking forward to having this library in Boost. Finally, I would like to thank Peter for writing and sharing this library. Regards, &rzej;

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