April 2024 - Boost - lists.preview.boost.org

[release] Boost 1.85.0
by Marshall Clow 28 May '24

28 May '24

Release 1.85.0 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: * Boost.Charconv: A high quality implementation of <charconv> in C++11, from Matt Borland. * Boost.Scope: A collection of scope guard utilities and a unique_resource wrapper, from Andrey Semashev. The release also contains numerous enhancements and bug fixes for existing libraries. For details, including download links, see <http://www.boost.org/users/news/version_1.85.0> You can also download directly from: <https://boostorg.jfrog.io/artifactory/main/release/1.85.0/> 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. -- The Boost Release Team Marshall Clow, Glen Fernandes

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modern logic classes
by g.peterhoff＠t-online.de 18 May '24

18 May '24

Hello, I would like to provide modern logic classes, please see https://github.com/boostorg/logic/issues/30 What are your opinions/comments on this? thx Gero

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GSOC '24 at Boost
by David Bellot 05 May '24

05 May '24

Hi all, Another year, another GSOC's coming! As you all know now, Inbal is in charge of managing our GSOC program at Boost. Over the past years, I had the pleasure to work with many of you and we had the chance to have many great students and mentors. This year, however, it seems we don't have enough mentors yet. I know it's just the beginning of the year, but I would like to encourage you to join this program as a mentor, and help students to participate in Boost and become great C++ developers. It's a very rewarding journey I took myself years ago and you will learn so much, both on the technical and human side. If you want to become a mentor, just add your name to this shared spreadsheet: https://docs.google.com/spreadsheets/d/1_eUWRsXnhi_JwKZbHZsGQf3WNUESsAPE4lV… Cheers, David

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Proposal for yet another MQTT library for Boost
by Takatoshi Kondo 01 May '24

01 May '24

Dear Boost Developers, I'd like to propose a MQTT library to the Boost Libraries. Repository link: https://github.com/redboltz/async_mqtt Document link: https://redboltz.github.io/async_mqtt/doc/5.0.0/index.html Here is characteristics of async_mqtt: - C++17 or later is required. - async_mqtt supports Boost.Asio style completion tokens. - e.g. use_future, deferred, use_awaitable, callback functions, etc - Not only MQTT client but also MQTT server is supported. - User can use this library to develop MQTT broker. - Sample MQTT broker application is included. - Both MQTT v3.1.1 and v5.0 are supported. - In addition, undetermined protocol version is supported for server implementation. In this case, the protocol version is decided when you receive CONNECT packet. - Continuous packet sending - Users can send the next MQTT packets before the previous sending is not completed (completion handler is not invoked yet). - Auto acquiring/mapping topic alias is supported. - In addition, when resending a PUBLISH packet after reconnecting, the topic alias is removed and the original topic is restored. It is required by MQTT v5.0 spec. - Packet based send()/recv() APIs. - MQTT has various packets and some of their fields are optional. In order to keep simple APIs, async_mqtt uses packet based APIs. - See https://redboltz.github.io/async_mqtt/doc/5.0.0/tutorial/send_recv.html - Layered archtecture - async_mqtt can have predefined TCP, TLS, WS, WSS, and user defined underlying layer. Users can access the underlying layer using next_layer() member function of MQTT endpoint. So you can configure any layers by yourself. e.g. tcp_no_delay, set send/recv buffer size, etc - See https://redboltz.github.io/async_mqtt/doc/5.0.0/tutorial/create_endpoint.ht… - High performance - See https://redboltz.github.io/async_mqtt/doc/5.0.0/performance.html Background I have developed another mqtt library mqtt_cpp https://github.com/redboltz/mqtt_cpp since 2015. It is widely used but has some limitations. For example: - The functions are directly mapped to packets(publish, subscribe, etc), so optional features are not designed cleanly. - Due to set_publish_hander / on_publish style handler design, Completion Token cannot be supported. Based on this 9years experience, I designed the new MQTT library. This is async_mqtt. I would appreciate if you could endorse this library. Regards, Takatoshi Kondo

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Re: [boost] modern logic classes
by g.peterhoff＠t-online.de 29 Apr '24

29 Apr '24

Here is an update. Since a few boost libraries use tribool, these would have to be converted to bool3. Unfortunately it is not that easy to establish a new boost library. Especially if it is incompatible with previous implementations. thx Gero

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Can we get rid of auto-linking?
by René Ferdinand Rivera Morell 29 Apr '24

29 Apr '24

Today I got bit by auto-linking again. As I forgot to define BOOST_ALL_NO_LIB in a CI build. I can't remember a time when auto-linking has been beneficial. And I've lost the number of times I've had to answer user questions with "Auto-linking is getting in the way. Define BOOST_ALL_NO_LIB and link normally." more times than I can count. If there was ever a benefit to auto-linking it has not surpassed the drawbacks. So.. Can we get rid of auto-linking? -- -- René Ferdinand Rivera Morell -- Don't Assume Anything -- No Supone Nada -- Robot Dreams - http://robot-dreams.net

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Emitting complete type information in boost-python docstrings
by Jakob van Santen 29 Apr '24

29 Apr '24

Hello, I’m not sure if this is the right forum for this question, but here goes: I work on a large scientific codebase that is heavily tied to boost, and that most users interact with via boost-python. Lately I have been working on generating PEP 484 type stubs for the ~1000 classes it exposes in order to enable static type checking and code completion in editors. This required some modifications to boost-python itself in order to get complete type information into the generated docstrings, where it can be consumed by external tooling to generate stubs: https://github.com/boostorg/python/pull/417 I have found this quite useful, and suspect it might be useful for others as well to have it in a Boost release. Can anyone give me a pointer as to how to make that happen, or let me know where or whom I should be asking instead? I asked on cplusplus-sig(a)python.org <mailto:cplusplus-sig@python.org>, which was the place many years ago, but that list seems to have died out. Many thanks in advance! Cheers, Jakob ------------------------------------------------------- Jakob van Santen DESY - Deutsches Elektronen-Synchrotron Platanenallee 6, D-15738, Zeuthen Office 2L/32 +49 (0)33762-7-7233 -------------------------------------------------------

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BOOST_THREAD_HAS_EINTR_BUG...
by David Bien 26 Apr '24

26 Apr '24

Not really sure where to bring this issue up. I have a singleton globals object with a session manager, share manager, etc. that is destroyed atexit() on final reference release. There are a few mutexes in the implementation. This functions fine on Windows, MacOS, etc - the globals object is released during atexit() and shutdown proceeds normally. Under Linux when BOOST_THREAD_HAS_EINTR_BUG is defined we SIGABRT at this: ~mutex() { BOOST_VERIFY(!posix::pthread_mutex_destroy(&m)); } The verify fails and we abort(). When I define BOOST_THREAD_HAS_NO_EINTR_BUG we do not abort - which means that posix::pthread_mutex_destroy() returns 0 in the case where BOOST_THREAD_HAS_NO_EINTR_BUG is defined and returns non-zero in the case of it not being defined. Guidance? Also point me at a better place for this discussion if there is such a place. Thanks, David Bien

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question about singleton_pool
by 李重斌 26 Apr '24

26 Apr '24

I want to use singleton_pool to manage memory. This is just an example which tests it. My question: the first time i allocate 100 spot object, and free them. If i allocate some spot objects, and the number of them is less than 100. no more memory is needed, there is no need to allocate memory from os again. but the fact is another memory block is allocated. The first block is 4016 bytes (sizeof(Spot) = 40), the second block is 8016 bytes. This is not as my imagine. Is there something wrong with these code? ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// std::cout << "size of Spot " << sizeof(Spot) << " bytes\n"; std::cout << "test singleton_pool firt time\n"; const size_t NumSpots = 100; Spot* p1 = static_cast<Spot*>(spot_pool::ordered_malloc(NumSpots)); for (size_t i = 0; i < NumSpots; i++) { p1[i].x = 1; p1[i].y = 1; } spot_pool::ordered_free(p1); std::cout << "test singleton_pool second time\n"; Spot* p2 = static_cast<Spot*>(spot_pool::ordered_malloc(NumSpots/2)); for (size_t i = 0; i < NumSpots/2; i++) { p2[i].x = 2; p2[i].y = 2; } spot_pool::ordered_free(p2); /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

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UUID design discussion
by Peter Dimov 26 Apr '24

26 Apr '24

We've been discussing some UUID design issues in, well, issues in the Uuid repo, namely https://github.com/boostorg/uuid/issues/96 and, for context, https://github.com/boostorg/uuid/issues/113. This topic might be of wide interest to developers, so I thought it would be better to have this list know about it. Anyone who has an opinion on the matter is welcome to express it in the issue, or here. In addition to the questions raised in #96, namely, how should the constructors and the accessors of `uuid` look like (once we somehow move away from the public `data` member), here are some more topics of interest: * Should a default-constructed `uuid` remain uninitialized, or should the default constructor produce the nil Uuid? (Uninitialized is not a good look in 2024 because safety. On the other hand, `new uuid[ 1048576 ]` will start doing a `memset`.) * At the moment wide strings are processed by the name generators by converting every wchar_t to 32 bit, then hashing the bytes, zeroes and all. This doesn't strike me as correct. I think that the string should be converted to UTF-8 on the fly (with 32 bit wchar_t assumed UTF-16 and 32 bit wchar_t assumed UTF-32.)

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