January 2022 - Boost - lists.preview.boost.org

Boost.Text is looking for a (mini-)review manager
by Zach Laine 07 Dec '22

07 Dec '22

I've made all the recommended changes to Boost.Text that came up in the review. Glen, the previous review manager, recommended a mini review of Boost.Text once I'd made those changes. If you'd like to manage the mini-review, please let me know. For everyone, including potential reviewers and review managers, here are the major changes: * All the specific review feedback issues have been addressed. * The string layer is now gone. * The text layer got a major re-work. It is now a set of template-based adaptors (basic_text<>, vs. a text typedef. etc.), which lets everyone get what they want. You can change the underlying storage type (including whatever allocator you prefer), select UTF-8 or UTF-16, and change the normalization form. Glen recommended I drop this layer, but the library is way less useful without this stuff, and these changes address all the concerns raised about the text layer in the review. The updated docs can be found here: https://tzlaine.github.io/text/doc/html/index.html Oh yeah, and I added concept constraints to the whole library when you build in C++20 mode. Zach

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[review][JSON] Review of JSON starts today: Sept 14 - Sept 23
by Pranam Lashkari 09 Aug '22

09 Aug '22

Boost formal review of Vinnie Falco and Krystian Stasiowski's library JSON starts today and will run for 10 days ending on 23 Sept 2020. Both of these authors have already developed a couple of libraries which are accepted in Boost(boost beast and Static String) This library focuses on a common and popular use-case for JSON. It provides a container to hold parsed and serialised JSON types. It provides more flexibility and better benchmark performance than its competitors. JSON highlights the following features in the documentation: - Fast compilation - Require only C++11 - Fast streaming parser and serializer - Easy and safe API with allocator support - Constant-time key lookup for objects - Options to allow non-standard JSON - Compile without Boost, define BOOST_JSON_STANDALONE - Optional header-only, without linking to a library (a point I would like to add in highlight: it has cool Jason logo 😝) To quickly understand and get the flavour of the library take a look at "Quick Look" <http://master.json.cpp.al/json/usage/quick_look.html> You can find the source code to be reviewed here: <https://github.com/CPPAlliance/json/tree/master> You can find the latest documentation here: <http://master.json.cpp.al/> Benchmarks are also given in the document which can be found here: <http://master.json.cpp.al/json/benchmarks.html> Some people have also given the early reviews, the thread can be found here: <https://lists.boost.org/Archives/boost/2020/09/249745.php> Please provide in your review information you think is valuable to understand your choice to ACCEPT or REJECT including JSON 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 here: <http://www.boost.org/community/reviews.html> Thank you for your effort in the Boost community. -- Thank you, Pranam Lashkari, https://lpranam.github.io/

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[container] Contributing 'stationary_vector' to Boost
by Mehrdad Niknami 13 Jun '22

13 Jun '22

Hi all, Happy new year! New mailing list member here. I've developed an STL-style stationary_vector class that retains elements in-place when growing. Very briefly, it is effectively a piecewise-contiguous vector, with the following advantages over vector: - Appending has O(1) overhead in the *worst* case (e.g., push_back() does not move elements) - Insertion and random-access can be done in parallel, as prior iterators & references remain valid This has a variety of benefits, including better UX (no "hiccups" due to reallocations), and the ability to simplify parallel processing of streaming data. It occurred to me the larger C++ community might find this useful. I was wondering if there would be interest in incorporating it into Boost.Container, and if so, what steps I could take to make that happen? I'm of course happy to discuss the design etc. with anyone who might be interested. Summary: https://github.com/mehrdadn/libvital/blob/master/doc/vital/container/statio… Implementation: https://github.com/mehrdadn/libvital/blob/master/include/vital/container/st… Thank you, Mehrdad

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[release] Boost 1.7.0 beta 1 released
by Marshall Clow 13 Apr '22

13 Apr '22

Boost release 1.77.0 beta 1 is now available at: <https://boostorg.jfrog.io/artifactory/main/beta/1.78.0.beta1/source/> The SHA256 checksums are as follows: 7a3a025451dfa2923129214eef7d16b03c02310a353d02158a549f6caa4284b0 boost_1_78_0_b1.tar.bz2 c491b1dcb916195598aa6581d6708d57fcc750516641c22511c088d572de9c07 boost_1_78_0_b1.tar.gz 35e7a3b0eb412a3933e57c72ba96374eb7d88ff1f89dbec62a16d67ffea2105a boost_1_78_0_b1.7z e6b68feb2f63401c96ca9fe25e939b409189fbe526a6e784e4bd69832c8f09cb boost_1_78_0_b1.zip For details of what's in the release, see <https://www.boost.org/users/history/version_1_78_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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[Graph] Attempt to resolve open issue
by Anne van de Graaf 10 Mar '22

10 Mar '22

Hello all, I am trying to get an open issue in Boost.Graph resolved. Since I haven't received any response at the corresponding GitHub page nor from the Boost Users mailing list (where I posted the below message last Monday), I am reaching out to you. My aim is to get in touch with the maintainer(s) of Boost.Graph in order to discuss what is the preferred/most efficient way to fix the issue. Since this is my first post to this mailing list, please accept my apologies if you feel this is not the right way to get in touch with the maintainers. In that case, I would appreciate it very much if you could kindly explain what I should have done instead. Please find below a copy of my message that I sent last Monday to the Boost Users mailing list. Thank you very much for your attention and any replies. Original message: When I remove a vertex from a graph, I occasionally experience a crash (on a system running Red Hat Enterprise Linux 8.5). I have been able to replicate the behavior with the following test program: #include <vector> #include <boost/graph/adjacency_list.hpp> int main() { using MyGraph = boost::adjacency_list<boost::setS, boost::vecS, boost::undirectedS>; using MyVertexDescriptor = boost::graph_traits<MyGraph>::vertex_descriptor; using MyVertexDescriptorVec = std::vector<MyVertexDescriptor>; MyGraph g; MyVertexDescriptorVec vertices{ boost::add_vertex( g ), boost::add_vertex( g ), boost::add_vertex( g ) }; boost::add_edge( vertices[0], vertices[1], g ); boost::add_edge( vertices[1], vertices[2], g ); boost::clear_vertex( vertices[0], g ); boost::remove_vertex( vertices[0], g ); return 0; } Also on a Windows platform, I observe similar behavior. When I build the above code with Microsoft Visual Studio 2019 (MSVC 14.27.29110) and run it with a debugger, a debug assertion is triggered ("cannot increment value-initialized map/set iterator"). In both cases (on Linux and Windows platforms), the debugger reveals that the problem is at line 2071 of boost/graph/detail/adjacency_list.hpp. For clarity, I have copied the involved template function below: template < class EdgeList, class vertex_descriptor > inline void reindex_edge_list( EdgeList& el, vertex_descriptor u, boost::disallow_parallel_edge_tag) { for (typename EdgeList::iterator ei = el.begin(); ei != el.end(); ++ei) // line 2071: increment operator fails { if (ei->get_target() > u) { typename EdgeList::value_type ce = *ei; el.erase(ce); --ce.get_target(); el.insert(ce); } } } While I was searching for a proper place to post my question, I found the following issue at GitHub (which was opened on July 1 of this year): https://github.com/boostorg/graph/issues/268. This appears to be the exact same issue. So last week, I added a comment saying that I am facing the exact same problem. Unfortunately, so far no one has responded yet. To me, it seems that the problem is well-understood. Also, some have proposed a bug fix to resolve the issue (including a pull request). Nevertheless, no progress has been made over the past months. So I was just wondering what is the best way to proceed if we want to fix the issue in Boost itself? Is there anything that I can do (apart from starting this thread) to help in resolving the issue? Any feedback is greatly appreciated. Kind regards, Anne van de Graaf

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Primary test compilers in Boost release notes
by Peter Dimov 01 Feb '22

01 Feb '22

We have an issue, https://github.com/boostorg/boost/issues/610, that points out that the "Primary test compilers" section in the Boost 1.78 release notes is misleading, because it doesn't actually reflect whether a Boost library works with a specific compiler or not. The specific example cited is Multiprecision. The release notes say that on Linux, the following C++11 GCC compilers are "primary": GCC, C++11: 4.7.3, 4.8.5, 11 However, Multiprecision doesn't work with GCC 4.7.3 or 4.8.5, and likely never will, because these compilers do not actually implement the C++11 standard. (They don't implement reference qualified member functions and don't have a conforming <type_traits> header.) It would be better for everyone involved if the primary test compilers are somewhat aligned with (a) what Boost libraries actually support or require, and (b) what Boost libraries actually test with. The section historically lists what's in our test matrix, but nowadays most libraries depend on CI for testing, specifically on Github Actions (after the untimely death of open source Travis) and Appveyor. There's a fair bit of discussion in the linked issue above, but what I think is reasonable to list as primary test compilers as far as GCC is concerned is something like C++03: 4.8, 4.9, 5 C++11: 4.8(*), 4.9(*), 5 I would start with 4.8, because this is what GHA has on its 18.04 image. C++03 needs to have GCC up to 5 because this is the default -std level for these versions (GCC 6 is -std=c++14 by default), and the system- provided Boost is compiled with the default. 4.8 has enough of C++11 so it's possible for C++11 libraries to support it without much heroics, but we could go either way on this one, hence the asterisk.

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[GSoC 2022] [Graph] Potential mentors
by Dev Jain 15 Jan '22

15 Jan '22

Hello everyone. I am Dev Jain, a sophomore student pursuing a Bachelors in Computer Science and Engineering from IIT Jammu. I am passionate about discrete mathematics, and in particular graph theory and graph algorithms. I would like to contribute to the Boost Graph Library. I can't find any project ideas for the BGL in recent years of GSoC. Are there any people active with BGL, and any prospective mentors? I understand that, it is recommended to come to the mailing list asking for mentors by describing an idea, but I wanted to ask this since for many years a BGL project hasn't been proposed in the ideas list. Thanks.

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Does anybody know why boost::array does not support multiple dimensions?
by Ivan Matek 10 Jan '22

10 Jan '22

I don't know much about library development, but with variadic templates does not seem so hard, although every library development is much harder than regular user code. Sure boost::array probably wants to support ancient compilers, but variadic version could exist only for "modern"(I do not consider >10y old standards modern) C++. I found this std:: proposal http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2013/n3794.html#Ch05 from 9 y ago, also author seemed to have some working impl on github https://github.com/CTMacUser/ArrayMD/tree/master/include/boost/container But I guess none of it ever progressed. Does anybody knows more about this? It is not trivial since there are probably a ton of edge cases, typdefs, semantics(what should size return?, I would say array of dims) to deal with, but I think it would be a nice extension since I find nested std::array hideous (with current syntax), e.g.: std::array<std::array<int,3>, 4> arr; I would like to have this boost::array<int,4,3> arr; P.S. I know I can use Eigen or some other library, but I think if not std then at least boost should support simple way to have multidim arrays.

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Error with geometry buffer?
by KL 10 Jan '22

10 Jan '22

Hi, Boost Geometry 1.78, linux Â I was getting bad results with my calculations so I decided to narrow down the implementation up to the point I got the following problematic code: Â typedef boost::geometry::model::point <double, 2, boost::geometry::cs::cartesian> Vector2d; Â int main (){ Â Â Â Â Â Â Â Â multi_polygon <polygon <Vector2d> > mp; Â Â Â Â Â Â Â Â /*{ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â polygon <Vector2d> poly; Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {0, 0} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {0, 4} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {4, 4} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {4, 0} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â correct( poly ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â mp.push_back(poly); Â Â Â Â Â Â Â }*/ Â Â Â Â Â Â Â { Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â polygon <Vector2d> poly; Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {10, -1} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {14, -1} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {10, -2} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {14, -2}Â ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â correct( poly ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â mp.push_back(poly); Â Â Â Â Â Â Â } Â Â Â Â Â Â Â Â Â boost::geometry::strategy::buffer::join_miter join_strategy; Â Â Â Â Â Â Â boost::geometry::strategy::buffer::end_flat end_strategy; Â Â Â Â Â Â Â boost::geometry::strategy::buffer::side_straight side_strategy; Â Â Â Â Â Â Â boost::geometry::strategy::buffer::point_square point_strategy; Â Â Â Â Â Â Â Â boost::geometry::strategy::buffer::distance_symmetric <double> distance_strategy( 2 ); Â Â Â Â Â Â Â boost::geometry::model::multi_polygon <polygon <Vector2d> > result; Â Â Â Â Â Â Â Â boost::geometry::buffer( mp, result, distance_strategy, side_strategy, join_strategy, end_strategy, point_strategy ); Â Â Â Â Â Â Â Â cout << dsv( result ) << endl; Â Â Â Â Â Â Â Â return 0; Â } Â and the result I get is: ((((13.7169, -3.13232), (13.5149, -3.94029), (12, -3.56155), (10.4851, -3.94029), (10.2831, -3.13232), (9.51493, -2.94029), (0.0749244, 0.221833), (10, 1), (14, 1), (23.9251, 0.221833), (14.4851, -2.94029), (13.7169, -3.13232)))) Â Notice the two points: (0.0749244, 0.221833) and (23.9251, 0.221833) Â I have multiple complex (concave) shapes which behave worse than that simple rectangle. But it is a starting point here. Â Did I do something wrong? I need to get my job done, any alternative or helping code massaging ? Â Thanks --Â MKL Â

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[ASIO] Need help reading the documentation
by Andrzej Krzemienski 01 Jan '22

01 Jan '22

Hi Everyone, I need some help in reading the ASIO docs. I am looking at the following example from the docs https://www.boost.org/doc/libs/1_78_0/doc/html/boost_asio/example/cpp17/cor… It calls one of the overloads of async_write in line co_await async_write(socket, boost::asio::buffer(data, n), use_awaitable); The reference section lists eight overloads: https://www.boost.org/doc/libs/1_78_0/doc/html/boost_asio/reference/async_w… But it is still impossible for me to figure out which one it is. `use_awaitable` is documented as "completion token" in https://www.boost.org/doc/libs/1_78_0/doc/html/boost_asio/reference/use_awa… There is some mention of completion token at https://www.boost.org/doc/libs/1_78_0/doc/html/boost_asio/reference/asynchr… So I would expect the name `CompletionToken` to appear in the documentation of `async_write`. Am I missing something? Regards, &rzej;

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