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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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[ASIO] Do I have to use shared_ptrs with ASIO?
by Andrzej Krzemienski 29 Dec '21

29 Dec '21

Hi Everyone, I am looking at an example implementation of an asynchronous TCP echo server in Boost.ASIO library: https://www.boost.org/doc/libs/1_77_0/doc/html/boost_asio/example/cpp11/ech… It uses a shared_ptr in the implementation to store the things related to session: socket handle, data buffers. I tried to modify it in a number of ways to avoid the usage of shared_ptr (and any form of shared ownership), but they all failed. It looks like I have to use a shared_pointer (or equivalent) when I use ASIO sockets. But conceptually, there is never a point in time where two tasks have to access members of this `session` concurrently: they are always sequenced. So, at least conceptually, there should be a way to do this with a session type that is only movable, with unique ownership: a task does its job with the session and then moves it to the subsequent task. So is this necessity to use a shared pointer an unnecessary and suboptimal design choice? Or is there something fundamental that prevents the unique ownership of buffers and socket handles? Or maybe is there a way to do it in ASIO that I overlooked? I am not trying to solve any specific problem. It just strikes me that a shared_ptr is used in a demo example for the library. I was always of the opinion that a shared_ptr is often abused as a way of doing an ad-hoc GC. Regards, &rzej;

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Seeking help for kickstart
by Rahul Sharma 23 Dec '21

23 Dec '21

Hello everyone, I read all the information given on the blog pages and websites sent to me via email which I received when I subscribed to this mailing list, but I am too confused and I am not able to figure out from where to start and how to find some beginner friendly issues and projects to work on. Hoping for help and guidance to kickstart this journey. Accept my apologies if this is not the proper way to communicate about such problems. Sent from [1]Mail for Windows References 1. https://go.microsoft.com/fwlink/?LinkId=550986

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To contribute to this community.
by Rahul Sharma 22 Dec '21

22 Dec '21

Hello everyone, I am Rahul Sharma currently a sophomore at IIT Guwahati pursuing my B.Tech with major in Civil Engineering. I am very much enthusiastically inclined towards technology and want to pursue my carrier in the field of technology. And also I am very much interested in the open source communities and would really like to be part of such a community and to work with other peers with the same vision and to work with dedication on some really cool real world projects. My tech stack comprises of programming languages like c and c++ and am also a front end web developer and currently learning the back end web development with react. Seeking for the guidance from the other experienced peer developers and mentors. Sent from [1]Mail for Windows References 1. https://go.microsoft.com/fwlink/?LinkId=550986

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[release] Boost 1.78.0
by Marshall Clow 09 Dec '21

09 Dec '21

Release 1.78.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains numerous enhancements and bug fixes for existing libraries. For details, including download links, see <http://www.boost.org/users/news/version_1.78.0> You can also download directly from: <https://boostorg.jfrog.io/artifactory/main/release/1.78.0/> To install this release on your system, see <http://www.boost.org/doc/libs/release/more/getting_started/index.html> Thanks to everyone who participated in this release. Thanks, -- The Boost Release Team Marshall Clow, Michael Caisse, Glen Fernandes

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[release] Master branch is now open for merging
by Marshall Clow 08 Dec '21

08 Dec '21

No restrictions; the release calendar is up to date. https://boost.org/development Next milestone: 23-Feb Boost 1.79.0 closed for new libraries and breaking changes — Marshall

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boost.spawn: review requested
by Oliver Kowalke 06 Dec '21

06 Dec '21

Hi, I'd like to propose the new library boost.spawn (https://olk.github.io/) for review. boost.asio's boost::asio::spawn() uses the deprecated and inefficient boost.coroutine library. boost.spawn provides the same functionality while using boost.context's fiber directly. Oliver

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Boost::any typecasting issue(bad_any_cast)
by Daggumati, Rajesh 05 Dec '21

05 Dec '21

Hi Team, While doing typecasting from boost::any to DecodeErrorPayload_t, its throwing bad_any_cast .. class RegisterIONotification { public: enum NotifyType { TypeUnknown, TypeRegTx, TypeRegRx, TypeDecodeError }; NotifyType Type; boost::any Payload; typedef boost::tuple<std::string, BinaryBuffer_t> DecodeErrorPayload_t; RegisterIONotification(NotifyType type;,boost::any payload) { Type(type); Payload(payload); } }; I have called RegisterIONotification from other class function. void RegisterIOThreaded::OnDecodeError( const std::string& error, BinaryBuffer_t data ) { RegisterIONotification notify(RegisterIONotification::TypeDecodeError ,make_tuple(error, data)); ..... .... ... } While testing, I am getting bad_any_cast exception. TEST_F(...,...) { RegisterIONotification notify = sink.GetDataById(ID::NOTIFY_COMMS_STATUS, 0).GetValue<RegisterIONotification>(); ASSERT_EQ(RegisterIONotification::TypeDecodeError, notify.Type); //passed RegisterIONotification::DecodeErrorPayload_t payload; ASSERT_NO_THROW(payload = boost::any_cast<RegisterIONotification::DecodeErrorPayload_t>(notify.Payload));// Here its got failed...Please help me to fix this. } Regards, Rajesh D Please be advised that this email may contain confidential information. If you are not the intended recipient, please notify us by email by replying to the sender and delete this message. The sender disclaims that the content of this email constitutes an offer to enter into, or the acceptance of, any agreement; provided that the foregoing does not invalidate the binding effect of any digital or other electronic reproduction of a manual signature that is included in any attachment.

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