February 2020 - Boost - lists.preview.boost.org

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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Optional library
by anshu khare 27 May '20

27 May '20

Hi mentors I was going through the optional library of boost. I was facing some problem in understanding the code base. In lines from 94 to 97 in optional.hpp, the code is as follows: struct in_place_init_if_t { Struct init_tag{}; explicit in_place_init_if_t(init_tag) {} //not able to understand this line }; I understand that we are creating a structure in_place_init_if_t and inside that we are creating another structure init_tag and then we are calling the constructor of in_place_init_if_t. But I am not able to understand that what does it the constructor do when we pass init_tag as an argument to it. Is it same as we are creating a structure Car and then creating another structure wheels inside it and passing wheels as an argument to the constructor of car as follows: struct car { Struct wheels{}; explicit car(wheels) {} //not able to understand this line }; Could you please tell what is the significance of passing wheels as an argument in this counter example?

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Hiring mentors for Google Summer of Code 2020
by David Bellot 28 Mar '20

28 Mar '20

Hi Boost community, we are recruiting the mentors for the Google Summer of Code 2020. If you wish to be a mentor, please contact me directly and I'll send you an invite. We need at least 10 mentors this year. Obviously, a mentor comes with ideas of projects and proposals for this Summer. Best regards, David

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binomial distribution setter function
by Kemin Zhou 18 Mar '20

18 Mar '20

This is my first time posting in this mailing list. Not sure how to post to the developer only mailing list after reading the document for mailing list for a good half an hour. If I posted in he wrong mailing please let me know and kindly provide the developer mailing list. I am looking at the binomial.hpp file. I need to use the binomial object in a loop which requires to have high performance. I am thinking constructing the binomial object each time in the loop would be less efficient than if I construct a single object, the each time reset the p parameter and use the object. I am not sure why the setter method was not provided. 296 RealType success_fraction() const 297 { // Probability. 298 return m_p; 299 } 300 void set_success_fraction(RealType p) { 301 m_p=p; 302 } Line 296 is the getter method, I added the setter method at line 300. -- Kemin Zhou 858 366 8260

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boost thread strange behaviour
by Adham Sabry 08 Mar '20

08 Mar '20

hi , i am trying to learn executors and executors thread pools using with boost::async but i found strange behabiour when i make thread pool adaptor ea and submit tasks to it and make ea00 and submit tasks to it if i started ea with async , it automatically starts ea00 the attached file has the code i thought that async will only start the passed thread pool"adaptor" But i think there is underlying thing which gather all threads of different pools into single entity and starts them with any call to boost::async is this a bug??? i run this from windows 7 64 by visual studio 2017

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Boost.StaticString (formerly Boost.FixedString) is ready for release!
by Krystian Stasiowski 02 Mar '20

02 Mar '20

Hi all, After some post-review polishing, Boost.StaticString is good to go for release! I have been in touch with the review manager, and everything has been checked over. Repo: https://github.com/sdkrystian/static_string Docs: https://sdkrystian.github.io/doc/static_string Here are some things that have been changed post-review: - Library has been renamed from Boost.FixedString to Boost.StaticString. Class template fixed_string has been renamed to basic_static_string, and aliases have been added for common character types, similar to std::string. - constexpr support to the fullest extent supported by available compilers has been added. - Functions that will not throw have been marked noexcept. - Moved to a single header configuration. - std::hash and boost::hash_value support has been added. - It has been decided that functions will throw on capacity overflow. - A specialization for when the capacity is 0 has been added that has no member. Additionally, the type of the member used to store the size of the string is now statically chosen to be the smallest possible width unsigned standard integer type that can hold all the needed size values. - operator+ has been implemented. - Floating point conversion support has been added to to_static_string/to_static_wstring. - Lots of bugs fixed. More behind the scenes, a bunch of optimizations have been added, taking advantage of the fact that the capacity is part of the type and known at compile time. Again, thank you all who participated in the review, and thank you Joaquin for managing it! Regards, Krystian Stasiowski

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Projects for GSoC 2020
by David Bellot 01 Mar '20

01 Mar '20

Hi Boost community, so far we received a few good contributions for projects for GSoC 2020. The proposals are from our usual mentors but I'm surprised we don't have more projects in data structures and algorithms. Most of what we have concern numerical problems. It's great but I wish to see more diversity in the type of projects we propose. We want to attract the best students around the world and push toward new C++ standards and improvements of what we already have. Being a mentor is a great experience and on top of it, without too much effort, you will get someone of quality working for you during all the summer. The wiki page for projects is here: https://github.com/boostorg/wiki/wiki/Google-Summer-of-Code%3A-2020 Please come, edit and contribute. Cheers, David

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What is the right way to close and clean boost::log
by JH 01 Mar '20

01 Mar '20

Hi, I built boost::log in my application library, it created boost::log::sinks::synchronous_sink<boost::log::sinks::text_file_backend> and close it by calling the boost::log::core::get()->remove_all_sinks() in destructor of the Log library, then one of my application link to my log library got Segmentation fault when it exited: Program received signal SIGSEGV, Segmentation fault. 0x00007ffff5fdd961 in boost::log::v2_mt_posix::core::remove_all_sinks() () from /usr/lib/x86_64-linux-gnu/libboost_log.so.1.65.1 If I add boost::log::core::get()->remove_all_sinks() in my application main before it return 0, the segmentation was gong, but it stuck. What is the proper right way to close and clean the boost::log? There is a blog suggested to run boost::log::core::get()->remove_all_sinks() when the main end, but that does not seem work. https://www.boost.org/doc/libs/1_62_0/libs/log/doc/html/log/rationale/why_c… Thank you. Kind regards, - jupiter

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Cryptography for Boost.
by Mikhail Komarov 29 Feb '20

29 Feb '20

Hello! Cryptography for Boost. Again. It’s been some time since I’ve started developing so-called clean C++ cryptography implementation for my organization’s internal purposes. It was intended at first to be a cryptography framework fulfilling special cryptography schemes requirements, but eventually it has evolved into a full-featured suite, actively using and, sometimes, even based on Boost libraries. This turned out to be fine way to serve the Boost (and entire C++) community and to assemble a Boost version of a suite. So this letter is about wether there is still any interest in cryptography library for Boost and is there any sense to show the community what do I have for now? Sincerely yours, Mikhail Komarov nemo(a)nil.foundation

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[gsoc] Encourage original ideas
by Mateusz Loskot 29 Feb '20

29 Feb '20

Hi, I noticed there may be confusion among students regarding project ideas. I sense, students (sometimes) fail to find the GSoC guides [1] ... So, based on the first paragraph of [1], I have updated our wiki [2] placing this note to students: "To any potential students, in addition to the list of project ideas, we don't discourage original ideas proposed by students. " If any mentors here disagree, please let me know and I will remove it (or move it to GIL, which I'm involved with as a mentor). [1] https://google.github.io/gsocguides/student/finding-the-right-project [2] https://github.com/boostorg/wiki/wiki/Google-Summer-of-Code:-2020 Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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