August 2021 - Boost - lists.preview.boost.org

CMake Announcement from Boost Steering Committee
by Jon Kalb 13 Aug '24

13 Aug '24

The libraries produced by the Boost community have had a greater impact on the way that the C++ community writes code than any other library implementation. The focus of the Boost community will always be on the libraries, but it is undeniable that we are dependent on and often limited by the infrastructure of our trade. Years ago, the move to Git was contentious; yet, it was required to improve development. In a similar vein our build system has become an impediment for many developers and users, existing and prospective. Therefore, we, the Steering Committee, announce to the Boost community our desire and intent to move Boost’s build system to CMake for users and developers alike. We are soliciting comments and proposals from the community to guide the process and the goals. Our desire is that the community can come to consensus by the end of the calendar year with a vision of supporting users and developers. We understand that the actual process of achieving the end goal will be long, time consuming, and not without its share of conflict. We also recognize that the Boost community is comprised of bright and passionate individuals that are eager to get involved and help get work done. The members of the Steering Committee have been encouraged by the discussions and activity surrounding CMake on the mailing lists over the years and know that many people have voiced visions. We hope that each of you rejoins the discussion to support this initiative and contributes to the common goal of improving Boost’s integration into the broader C++ ecosystem. For the Boost Steering Committee, Jon Kalb, Chair jonkalb(a)boost.org

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Boost Governance?
by René Ferdinand Rivera Morell 09 Aug '24

09 Aug '24

A disclaimer: I write this solely as a Boost Library author. And not in any other capacity or representing any other interest. It's now been at least a year since Boost switched from the Software Freedom Conservancy to the Boost Foundation for its governance organization. But have people noticed any difference? Did you know that switch happened? Did you know that they held an election for the Board of Directors and for the Officers? Do you know when that election happened? Do you know who got elected? Do you know how they were selected? Do you know what their responsibilities are? Do you know what their bylaws are? Do you know their financials? More importantly: Did you answer "no" to any of those questions? As a library author, I can say I definitely answered no to many of those questions. This is a problem. As authors, without asking, we should know those answers from the organization that governs our work. We should have input into how that organization governs. In other words, we deserve open and transparent governance; not the closed and opaque status quo. -- -- René Ferdinand Rivera Morell -- Don't Assume Anything -- No Supone Nada -- Robot Dreams - http://robot-dreams.net

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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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Adding my sorting algorithm, ska_sort, to boost, attempt 2
by Malte Skarupke 24 Nov '21

24 Nov '21

Hi everyone, I started a discussion about this in October, but at the time the maintainer of the sort library was busy, then I was busy, so now it's January... I wrote a generalized version of radix sort a couple years ago and gave a talk about it here: https://www.youtube.com/watch?v=zqs87a_7zxw I would like to get a new version of that sorting algorithm into boost. It's faster than what I showed several years ago. It's also even more general and has a new interface that should be easier to extend. I uploaded the code here: https://github.com/skarupke/sort/tree/master The documentation is also already updated with new benchmark results. Let me know what's required to get this into boost. Would you like this in the form of a pull request? One of the big things that probably needs review is the interface, since radix sorting works differently than comparison based sorting. For most normal uses you just need to provide a sort key, but more complicated cases can get more complicated. I tried very hard to make everything easy, but I'd also be curious if others can come up with better ways of doing the interface. Thanks, Malte -- Malte Skarupke malteskarupke(a)fastmail.fm

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[any] [basic_any] This seems like a little pearl in Boost 1.77, but it's a bit underdocumented?
by Viktor Sehr 21 Sep '21

21 Sep '21

I just discovered basic_any which is a very nice addition for me. However it's a bit under-documented for the moment. For example: - I assume it's stack-allocated, does it allocate on the heap if assigned an object larger than the stack (like small_vector) or is this not allowed (like static_vector)? - An idea would also be to add a flag which breaks compilation if an object larger than the OptimizeForSize argument is assigned? - (For detail) If allocated on the stack, are the first bytes of the basic_any the same as the contained object? /Viktor

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Requesting feedback on boost::algorithm::is_clamped
by Ivan Matek 29 Aug '21

29 Aug '21

Hi everyone, I have made a MR for boost::algorithm::is_clamped. Details are on github <https://github.com/boostorg/algorithm/pull/86>. MR is in draft state since doc changes are missing, but tests and code should™ be correct. If you have no time for review of code I would highly appreciate the feedback on the usability of this function. In my work I needed it a few times within last year, but I would like to get feedback from 5-10 other professional developers from diverse backgrounds.

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Re: [boost] Regression tests not updating
by Nikita Kniazev 27 Aug '21

27 Aug '21

> What do you suggest as a solution? I agree that autodetection with no > way to override it is bad. (In my not yet finished CMake guidelines, I > advocate for only using autodetection to determine the default for > the configuration option, while still allowing the user to override it.) > But how does this translate to something actionable? How would you > have written the Nowide build/Jamfile? Sigh, if I had a good solution I would have presented it. An easiest and no-brainer way to tackle this is to have a per-library variable `is-boost-<library>-required/optional` on which library would have to omit checks (do not import Boost.Config, and do not pass checks that return `<build>no` to project/library requirements): ``` if is-boost-<library>-optional { import ../../config/checks/config : requires ; $(do-not-build-if) = [ requires ... ] ; } lib boost_<library> : ... : $(do-not-build-if) ; ``` However, in my opinion, a library must never add `<build>no` to its requirements by itself. Something external should decide if the build/checks failure is fatal or not: ``` rule can-be-built ( ... ) { import ../../config/checks/config : requires ; return [ requires ... ] ; } boost-install boost_<library> : @can-be-built ; ``` It would be perfect if the library could provide a meaningful explanation why it could not be built/describe not satisfied requirements, but that obviously requires a way more sophisticated system. > This is not a Mailman problem, this is a problem with how you are > replying or your mail client setup. Other users with gmail seem to not > have reply problems so I suspect it is not a gmail specific issue. A > quick look reveals that at least one concern is that your headers lack > the "in reply to". I am subscribed to the daily digest, I cannot reply to a message because I do not receive emails even if someone replied to my message or posted something to a thread I interested to be updated more frequently. > As a side-note: there are non-trivial issues with upgrading to mailman > v3; however, hopefully we will be able to upgrade things in the > not-to-far-off future. Thanks for working on that.

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Regression tests not updating
by Joaquin M López Muñoz 27 Aug '21

27 Aug '21

Hi, just a heads up that regression tests are not updating since Aug 12: https://www.boost.org/development/tests/develop/developer/summary.html https://www.boost.org/development/tests/master/developer/summary.html Thank you, Joaquín M López Muñoz

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Re: [boost] Unconditional conditional building is cursed"
by Nikita Kniazev 27 Aug '21

27 Aug '21

> But the problem has nothing to do with silently not building libraries. It's > caused by libraries assuming that Boost.Config is at ../config. Both have the same root cause -- no way to turn off these build checks. If the checks are not needed there is no need to import Boost.Config and assume its location too. P.S. I do not understand how to reply in the Boost mailing lists, please do not blame me if the message went to the wrong thread, I expressed my frustration about that previously, Boost needs to upgrade its Mailman to v3.

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Unconditional conditional building is cursed
by Nikita Kniazev 26 Aug '21

26 Aug '21

Some libraries (Context, Contract, Fiber, Json, Math, Nowide) are built conditionally and use checks from the Config library to do that (`import ../../config/checks/config : requires ;`). Apparently, it happens to be a PITA for some consumers. Vcpkg had to hack around that and update the hack every Boost release, but Boost 1.76 revealed problems in it ( https://github.com/boostorg/build/issues/724) and Boost 1.77 is blocked by it (https://github.com/microsoft/vcpkg/pull/19556#issuecomment-904702798) I have a mixed feeling about silently not building libraries. I understand that for a lot of people it is reasonable that the default stage build will not build a library on an unsupported compiler. However, it is absolutely bad and a confusing thing to a user that the input is silently ignored when a library is requested using the `--with-<library>` flag. A way to turn off the conditional building of the libraries could also be in debug purposes alongside fixing `--with-<library>` behaviour and making possible for vcpkg to live without resorting to hacking the boost build system. I have no affiliation to vcpkg and I am not a maintainer of any mentioned libraries. It is purely my observation about how Boost is used.

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Does boost have an assert that works nicely with constexpr evaluation, and if not should we add one?
by Ivan Matek 25 Aug '21

25 Aug '21

As you may know assert does not play nicely with constexpr evaluation. But std::is_constant_evaluated/if consteval gives us a way to check when the execution happens. https://www.godbolt.org/z/dfder8h16 Does something like this exist in boost, and if not would that be a nice addition? I can not figure out how to support line numbers, filename in a same way assert does, since assert will obviously just take the line info from where it is called. P.S. smart_assert is just a first name I thought of, I am fine with any name as long as it is not some lengthy monstrosity like is_constant_evaluated

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Need cancel() on async_resolve() to callback the resolve handler immediately
by sandeep m.v 25 Aug '21

25 Aug '21

Hi All, I'm looking for a solution for below problem. We're using async_resolve() to perform DNS resolution using boost::asio::ip::tcp::resolver. In few instances probably during network connectivity issues, async_resolve is taking more time. When our application timeouts in 15seconds while waiting for DNS resolution, cancel() is called on resolver. But, that doesn't callback to resolve handle immediately. When I tried to search for this, it looks like, when a cancel() is called on resolver, that doesn't cancel ongoing actual resolution but may cancel if there are any other pending asynchronous action. It's taking 40seconds at times to call resolve handler even when failed to resolve host and even after calling cancel on it. My application waits until resolve handler is called after cancel() to proceed further processing. Is it possible to stop that async_resolve() and get callback to resolve handle immediately after cancel()? If that's impossible, is there a way that we can stop that doesn't callback resolve handler later? Is it possible to close underlying socket related to async_resolve from my application? Thank you in advance. Regards, Sandeep

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BOOST_IS_CONSTANT_EVALUATED_INT(integer-expression)(integer-expression)
by Robert Ramey 24 Aug '21

24 Aug '21

A couple of questions regarding the above new boost config macro. a) I note that this "breaks the pattern" of BOOST_NO_... which I was expecting. I've got no complaint about this, just like being consistent when possible. b) My intended usage is something like: template<typename T> constexpr interval<T> get_interval(const & T t){ return BOOST_IS_CONSTANT_EVALUATED_INT(t) ? interval<T>(t, t) : interval<T>( std::numeric_limits<T>::min(), std::numeric_limits<T>::max() ); } is this the intended way to use this? If not, what would be the correct usage. c) In my Jamfiles I generally have a few tests which run conditionally on the config macro values like this: test-bsl-run_files test_array : A : : requires cxx11_hdr_array ; #BOOST_NO_CXX11_HDR_ARRAY What should I use with the above macro? Particularly confusing is the usage of _NO_ in the macro and the exclusion of _no_ in the requires variable. Should it be something like this. test test_is_constant_evaluted : A : : requires cxx20_no_is_constant_evaluated_int ; #BOOST_IS_CONSTANT_EVALUATED_INT d) Looks like part of this already checked into config.hpp on the develop branch. I would like to add something to my current develop to permit me to start using this now until you get the final code checked in. Any suggestions about the easiest way to do this? I'm ok with inserting some code temporarily but would prefer not to have to sprinkle it all over the place. Robert Ramey

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Strange b2 headers problem
by Edward Diener 24 Aug '21

24 Aug '21

I switched my main boost repository from the 'develop' branch to an earlier tagged boost release to try something out in that earlier release. Everything went fine with switching the main repository and all submodules. I wiped out all the header links from the boost subdirectory and I tried b2 headers, only to get: error: Cannot create link boost\property_map\parallel\basic_reduce.hpp to libs\property_map_parallel\include\boost\property_map\parallel\basic_reduce.hpp. error: Link previously defined to another file, libs\property_map\include\boost\property_map\parallel\basic_reduce.hpp. This makes no sense since there is a completely empty boost subdirectory under my main boost repository directory. How do I fix this problem ?

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[release]Boost 1.77.0
by Marshall Clow 22 Aug '21

22 Aug '21

Release 1.77.0 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 two new libraries and numerous enhancements and bug fixes for existing libraries. * Describe: A C++14 reflection library, from Peter Dimov. Provides macros for describing enumerators and struct/class members, and primitives for querying this information. * Lambda2: A C++14, dependency-free, single header lambda library, from Peter Dimov. For details, including download links, see <http://www.boost.org/users/news/version_1.77.0> You can also download directly from: <https://boostorg.jfrog.io/artifactory/main/release/1.77.0/> 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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Discuss: Editorial Control Over Repositories and Libraries
by Vinnie Falco 21 Aug '21

21 Aug '21

So, I have a whole bunch of new libraries marching towards completion and proposal for Boost. I have Boost.URL and Boost.HTTP-Proto in the works, and there is some code that I want to share between the two. Files like these: Algorithms to assist processing RFC7230 compliant input: <https://github.com/vinniefalco/http_proto/blob/9d3144c60b3426509b45cc63dbb3…> <https://github.com/vinniefalco/http_proto/blob/9d3144c60b3426509b45cc63dbb3…> <https://github.com/vinniefalco/http_proto/blob/9d3144c60b3426509b45cc63dbb3…> These are public interfaces, and they are equally useful to both URL and HTTP-Proto. They will also be likely useful to processing websocket handshake field values. It would be nice if I could put them in a separate repository with its own tests, documentation, and CI. But I don't know that this is enough meat on the bone so to speak, to justify as a complete new Boost library offering. When Boost.URL returns a std:::string the user has the option of providing a custom allocator. The library comes with this interface which uses a local stack buffer: <https://github.com/CPPAlliance/url/blob/111b83cc4726f3144194dc3546e096d60ac…> This can be used to avoid dynamic allocation when, for example - you want to apply decoding to a URL-encoded input, which happens often. Boost.HTTP-Proto would benefit from this class as well. Again we have the case of a common component that belongs in a separate repository. But this allocator isn't really related to the BNF-processing utilities mentioned above. So where would it go? As I use MSVC exclusively for regular development, I have put together a small unit test facility which is tailored to my workflow: <https://github.com/vinniefalco/http_proto/blob/9d3144c60b3426509b45cc63dbb3…> This has the flavor of Boost lightweight test, but also: * Redirects output to the Visual Studio IDE if a debugger is attached * Supports the model where one executable is built which holds all the tests * A command-line argument facility to specify individual test suites to run I use this in all of my Boost libraries and to-be-proposed libraries. I wouldn't say that it is user-facing. Currently I put a copy of the file in each library but I have made some changes and it would be better if I could put it in a shared place in the Boost tree. But it isn't public so it shouldn't be grouped with the BNF and the allocator stuff above. I am working on new libraries which do ASIO networking, and they use this handy mocking class which is used for testing stream algorithms: <https://github.com/boostorg/beast/blob/21cd552399aa8167ed53c21a74f3711c2c31…> This is a public interface, which users deploy for their own tests (for example the windows-tls project uses it). Again the case where I want to use it in tests for my own new libraries but without making a copy of the source. In other words in its own shared place. It does require ASIO, so I'm not sure it should be grouped with the rest of the stuff above. Now going back to these new libraries, I have Boost.HTTP-Proto which is a brand new library that speaks HTTP/1 but you have to bring your own networking. It is purely a low-level protocol library, but with a scope expanded from Beast to support more useful things that users need. Since networking is obviously needed I am developing the companion library Boost.HTTP-IO in parallel which uses ASIO to drive the protocol library. They use separate repositories and thus the protocol library is physically isolated, has its own tests, CI, and documentation, and so forth. There is a cosmetic issue where users have to write boost::http_proto::request if they want to declare a request container but then they have to write boost::http_io::write if they want to send the request over a socket (note the different namespaces). This is kind of annoying, and becomes even more annoying when you have to remember which namespace the error constant is located in: http_proto::error::end_of_message or http_io::error::end_of_file. One possibility is for these libraries to use the same namespace: boost::http. Or boost::http_proto. But this breaks the rule of one-repository, one-unique-namespace. Once these libraries are done I will at some point want to write Boost.Websocket-Proto and Boost.Websocket-IO which are similar to their HTTP counterparts (*). And then we will have twice the number of namespaces and error constant enums: boost::http_proto boost::http_io boost::websocket_proto boost::websocket_io and boost::urls These all have their own error enums called "error". If we create a separate repository for common code that all 5 of these libraries use, then that's a sixth namespace also with error code. Okay so that's the stuff that I've been pondering as I write this new code, are any of these real problems? What can I do about it? I'm interested in your thoughts. * The purpose of writing these new, seemingly duplicative libraries is to build on the experience of Beast to smooth out the discovered rough edges and provide a superior interface and implementation. -- Regards, Vinnie Follow me on GitHub: https://github.com/vinniefalco

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Any reason to not add asynchronous sink version of boost::log::add_file_log?
by Nicholas Neumann 19 Aug '21

19 Aug '21

The boost::log::add_file_log function in <boost/log/utility/setup/file.hpp> is a nice function for setting up a file sink. I had been using it and needed to switch from a synchronous frontend to an asynchronous one. But the sink returned is synchronous. Is there any reason to not add a version of the function which creates and returns an asynchronous frontend? Perhaps called something like add_async_file_log?

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Master Branch now open for merging
by Marshall Clow 15 Aug '21

15 Aug '21

No restrictions; the release calendar is up to date. https://boost.org/development <https://boost.org/development> Next milestone: 20-Oct Boost 1.78.0 closed for new libraries and breaking changes — Marshall

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Want to contribute
by Neeraj Khatri 15 Aug '21

15 Aug '21

Can I get help from the organization that how shall I start my contribution in this organization. Thank You ................ .........

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[Boost.Units] Runtime Unit Conversions
by C.D. Clark 15 Aug '21

15 Aug '21

Good day, I have been using Boost.Units for several years now, and it is a great library. I find it difficult to write code without it anymore. However, it does not do runtime unit conversions, so I write a little library that does https://github.com/CD3/UnitConvert It uses Boost.Spirit to parse strings into quantities, and was an excuse for me to learn about spirit. It supports create a boost::units::quantity<T> object from the runtime quantity. Would anybody be interested in adding this type of capability to the boost unit library? I am not a computer scientists, so I don't believe I would be able to propose something up to the boost standard on my own. cdclark -- C.D. Clark III, PhD Associate Professor Department of Physics Fort Hays State University 600 Park Street Hays, KS 67601 Ph: 785.628.4502

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I would like to add boost::algorithm::is_clamped, how to proceed?
by Ivan Matek 13 Aug '21

13 Aug '21

Hi, I would like to add is_clamped (that tests if the value is clamped, similar how we have std::is_sorted, std::sort). What would be the proper procedure? I have never committed to boost, so I have no access to any repository, no "contacts", so I have no idea if small proposals like this require just approval from owner or it needs broader discussion(for example in some cases it would be nice fix for missing chain comparison <https://www.geeksforgeeks.org/chaining-comparison-operators-python/> in core language, but then is_clamped name is not that nice, is_between might be nicer,...). Also I am not sure if this is the best place to ask for directions and do discussions, if you have some slack channel or forum you prefer please let me know. There was a proposal <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1440r0.html>for std::, but it is not in C++20. I have no relation to that proposal. regards, Ivan

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is_constant_evaluated
by Robert Ramey 11 Aug '21

11 Aug '21

Any chance of seeing a feature macro for HAS_IS_CONSTANT_EVALUATED appearing in Boost.Config any time soon? Robert Ramey

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[release] Boost 1.77.0 Release Candidate 1
by Marshall Clow 06 Aug '21

06 Aug '21

The first release candidates for the 1.77.0 release are now available at: <https://boostorg.jfrog.io/artifactory/main/release/1.77.0/source/> The SHA256 checksums are as follows: fc9f85fc030e233142908241af7a846e60630aa7388de9a5fafb1f3a26840854 boost_1_77_0_rc1.tar.bz2 f2dd9722b21450daf5ce8ef82c2d99c7ec304f913ee6c6b7f047d5639503dda1 boost_1_77_0_rc1.7z 5347464af5b14ac54bb945dc68f1dd7c56f0dad7262816b956138fc53bcc0131 boost_1_77_0_rc1.tar.gz d2886ceff60c35fc6dc9120e8faa960c1e9535f2d7ce447469eae9836110ea77 boost_1_77_0_rc1.zip 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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[multiprecision/mpc][math/quadrature] Why boost::multiprecision::exp gets stuck when evaluating complex-valued integral?
by Kirill Kudashkin 05 Aug '21

05 Aug '21

Dear all, I have encountered a problem while using Boost C++ libraries ( multiprecision/mpc.hpp, math/quadrature) which I cannot resolve. This problems appears when running the following piece of code || |#include <boost/math/constants/constants.hpp> #include <boost/math/quadrature/exp_sinh.hpp> #include <boost/multiprecision/mpc.hpp> #include <boost/multiprecision/mpfr.hpp> #include <boost/math/special_functions/fpclassify.hpp> namespace mpns = boost::multiprecision; typedef mpns::number<boost::multiprecision::mpc_complex_backend <50> > mpc_type ; typedef mpc_type::value_type mp_type ; int main() { using boost::math::constants::root_pi ; mpc_type z{mp_type(1),mp_type(1)} ; auto f = [&](mp_type x) { //actually I did not test if all these conditions are needed... if (boost::math::fpclassify<mp_type> (x) == FP_ZERO) { return mpc_type(mp_type(1)) ; }; if (boost::math::fpclassify<mp_type> (x) == FP_INFINITE) { return mpc_type(mp_type(0)) ; }; mp_type x2 = mpns::pow(x,2U) ; if (boost::math::fpclassify<mp_type> (x2) == FP_ZERO) { return mpc_type(mp_type(1)) ; }; if (boost::math::fpclassify<mp_type> (x2) == FP_INFINITE) { return mpc_type(mp_type(0)) ; }; mpc_type ex2 = mpns::exp(-z*x2) ; if (boost::math::fpclassify<mpc_type> (ex2) == FP_ZERO) { return mpc_type(mp_type(0)) ; }; return ex2 ; } ; mp_type termination = boost::math::tools::root_epsilon <mp_type> () ; mp_type error; mp_type L1; size_t max_halvings = 12; boost::math::quadrature::exp_sinh<mp_type> integrator(max_halvings) ; mpc_type res = integrator.integrate(f,termination,&error,&L1) ; mpc_type div = 2U*mpns::sqrt(z) ; mpc_type result = (mpc_type(root_pi<mp_type> ())/div) - res ; return 0; } | ||Namely, the problem appears when evaluating the exponent. The code is compiled without any problems, but hangs on computing | mpc_type ex2 = mpns::exp(-z*x2) ;| It was possible to go into the function while debugging. It crashed eventually, when the compiler reached "unable to resolve non-existing file.../src/init2.c". I let it run for a while checking the call stack. It appears that the programs is stuck atcalling ___gmpn_sub_n_coreisbr(). Or better, in the call stuck it appeared frequently. I did several tests. The real-valued version (with mpfr_backend <2000>) works without any problems. cpp_complex_backend <100> works fine, but I could not test higher precision yet, since it is much slower. I found a work-around which is not ideal. Namely, mpc_type ex2 = mpc_type(mpns::exp(x2)) ; mpc_type ezx2 = mpns::pow(ex2,-z) ; works fine with mpc_complex_backend <2000>. The lambda-function as it is declared in the code above works and yields correct numbers. The problem appears when it is called from the integrator. My system. I use openSUSE Tumbeleweed. I installed boost libraries as provided by |boost_1_76_0-gnu-mpich-hpc-devel.| Complier -> g++, cppStandard gnu+17. I check that I have all libs, e.g. libgmp, libmpc, libmpfr and etc. All headers are present (the programs is complied without any warnings). Sorry for a lengthy question. Thank you in advance and Best wishes, Kirill ||

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Reminder: The Master branch will be closing for the 1.77.0 release on WEDNESDAY 4-August
by Marshall Clow 04 Aug '21

04 Aug '21

Release calendar here: https://www.boost.org/development/index.html — Marshall

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Re: [boost] Reminder: The Master branch will be closing for the 1.77.0 release on WEDNESDAY 4-August
by Gavin Lambert 03 Aug '21

03 Aug '21

On 3/08/2021 11:57 am, Andrey Semashev wrote: >> The docker image that the tools get run from doesn’t have “linux/magic.h” >> >> More as we discover it. > > I would like to know more about this issue. In particular, what Linux > system lacks this file (distro, kernel version, etc.). Maybe, this is > worth fixing before the release. Git history suggests that the file started existing in linux kernel 2.6.19 and remains since. Although it moved from one folder to another in the internal kernel source tree in kernel 3.7, but that shouldn't affect its existence in the userspace include dirs, unless something is using the wrong include paths.

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