October 2021 - 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

17 46

[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/

21 73

[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

7 19

[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;

8 21

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

8 10

conversion of catched exception to shared_ptr
by rajesh daggumati 08 Nov '21

08 Nov '21

rajesh daggumati <rajeshdaggumati9999(a)gmail.com> 09:59 (4 hours ago) to boost-users HI, please help me to solve below issue. Shared pointers are used in my code. class Exception : public virtual std::exception,public virtual boost::exception { --- }; class ExceptionTestException : public Exception { --- }; boost::shared_ptr<Exception> exceptionptr_t; try { Boost_Throw_function(ExceptionTestException("Hiii")); } catch(...) { boost::exception_ptr exceptionptr = boost::current_exception(); try { boost::rethrow(exceptionptr) } catch(boost::exception &e) { //here i need to assign this 'e' to shared pointer but this e is not in heap so then how to assign this e to sharedptr(exceptionptr_t). 1 way is : boost::exception *ep = new ExceptionTestException(e); exceptionptr_t(ep); here we know that exception_ptr is having ExceptionTestException but in some cases, we dont know which type of excepiton we have in exception_ptr in runtime. then how to assign to shared_ptr

4 4

boost::trim_copy(boost::string_view()); // error
by Olaf van der Spek 31 Oct '21

31 Oct '21

Hi, Why does the overload for boost::string_view not work? The std one works. Could it be made to work? #include <boost/algorithm/string.hpp> #include <boost/utility/string_ref.hpp> #include <boost/utility/string_view.hpp> #include <iostream> #include <string_view> int main() { boost::trim_copy(boost::string_view()); // error boost::trim_copy(std::string_view()); } $ g++ t0.cpp In file included from /usr/include/boost/algorithm/string.hpp:19, from t0.cpp:1: /usr/include/boost/algorithm/string/trim.hpp: In instantiation of ‘SequenceT boost::algorithm::trim_copy_if(const SequenceT&, PredicateT) [with SequenceT = boost::basic_string_view<char, std::char_traits<char> >; PredicateT = boost::algorithm::detail::is_classifiedF]’: /usr/include/boost/algorithm/string/trim.hpp:343:49: required from ‘SequenceT boost::algorithm::trim_copy(const SequenceT&, const std::locale&) [with SequenceT = boost::basic_string_view<char, std::char_traits<char> >]’ t0.cpp:10:19: required from here /usr/include/boost/algorithm/string/trim.hpp:319:20: error: no matching function for call to ‘boost::basic_string_view<char, std::char_traits<char> >::basic_string_view(const char*, const char*&)’ 319 | return SequenceT( | ^~~~~~~~~~ 320 | detail::trim_begin( | ~~~~~~~~~~~~~~~~~~~ 321 | ::boost::begin(Input), | ~~~~~~~~~~~~~~~~~~~~~~ 322 | TrimEnd, | ~~~~~~~~ 323 | IsSpace), | ~~~~~~~~~ 324 | TrimEnd | ~~~~~~~ 325 | ); | ~ In file included from t0.cpp:3: /usr/include/boost/utility/string_view.hpp:97:9: note: candidate: ‘template<class Allocator> boost::basic_string_view<charT, traits>::basic_string_view(const std::__cxx11::basic_string<charT, traits, Allocator>&) [with Allocator = Allocator; charT = char; traits = std::char_traits<char>]’ 97 | basic_string_view(const std::basic_string<charT, traits, Allocator>& str) BOOST_NOEXCEPT | ^~~~~~~~~~~~~~~~~ /usr/include/boost/utility/string_view.hpp:97:9: note: template argument deduction/substitution failed: In file included from /usr/include/boost/algorithm/string.hpp:19, from t0.cpp:1: /usr/include/boost/algorithm/string/trim.hpp:319:20: note: mismatched types ‘const std::__cxx11::basic_string<char, std::char_traits<char>, Allocator>’ and ‘const char*’ 319 | return SequenceT( | ^~~~~~~~~~ 320 | detail::trim_begin( | ~~~~~~~~~~~~~~~~~~~ 321 | ::boost::begin(Input), | ~~~~~~~~~~~~~~~~~~~~~~ 322 | TrimEnd, | ~~~~~~~~ 323 | IsSpace), | ~~~~~~~~~ 324 | TrimEnd | ~~~~~~~ 325 | ); | ~ In file included from t0.cpp:3: /usr/include/boost/utility/string_view.hpp:110:23: note: candidate: ‘constexpr boost::basic_string_view<charT, traits>::basic_string_view(const charT*, boost::basic_string_view<charT, traits>::size_type) [with charT = char; traits = std::char_traits<char>; boost::basic_string_view<charT, traits>::size_type = long unsigned int]’ (near match) 110 | BOOST_CONSTEXPR basic_string_view(const charT* str, size_type len) | ^~~~~~~~~~~~~~~~~ /usr/include/boost/utility/string_view.hpp:110:23: note: conversion of argument 2 would be ill-formed: In file included from /usr/include/boost/algorithm/string.hpp:19, from t0.cpp:1: /usr/include/boost/algorithm/string/trim.hpp:324:17: error: invalid conversion from ‘boost::range_detail::extract_const_iterator<boost::basic_string_view<char, std::char_traits<char> >, true>::typ’ {aka ‘const char*’} to ‘boost::basic_string_view<char, std::char_traits<char> >::size_type’ {aka ‘long unsigned int’} [-fpermissive] 324 | TrimEnd | ^~~~~~~ | | | boost::range_detail::extract_const_iterator<boost::basic_string_view<char, std::char_traits<char> >, true>::type {aka const char*} In file included from t0.cpp:3: /usr/include/boost/utility/string_view.hpp:107:23: note: candidate: ‘constexpr boost::basic_string_view<charT, traits>::basic_string_view(const charT*) [with charT = char; traits = std::char_traits<char>]’ 107 | BOOST_CONSTEXPR basic_string_view(const charT* str) | ^~~~~~~~~~~~~~~~~ /usr/include/boost/utility/string_view.hpp:107:23: note: candidate expects 1 argument, 2 provided /usr/include/boost/utility/string_view.hpp:78:23: note: candidate: ‘constexpr boost::basic_string_view<charT, traits>::basic_string_view(const boost::basic_string_view<charT, traits>&) [with charT = char; traits = std::char_traits<char>]’ 78 | BOOST_CONSTEXPR basic_string_view(const basic_string_view &rhs) BOOST_NOEXCEPT | ^~~~~~~~~~~~~~~~~ /usr/include/boost/utility/string_view.hpp:78:23: note: candidate expects 1 argument, 2 provided /usr/include/boost/utility/string_view.hpp:73:23: note: candidate: ‘constexpr boost::basic_string_view<charT, traits>::basic_string_view() [with charT = char; traits = std::char_traits<char>]’ 73 | BOOST_CONSTEXPR basic_string_view() BOOST_NOEXCEPT | ^~~~~~~~~~~~~~~~~ /usr/include/boost/utility/string_view.hpp:73:23: note: candidate expects 0 arguments, 2 provided In file included from /usr/include/boost/algorithm/string.hpp:19, from t0.cpp:1: /usr/include/boost/algorithm/string/trim.hpp: In instantiation of ‘SequenceT boost::algorithm::trim_copy_if(const SequenceT&, PredicateT) [with SequenceT = std::basic_string_view<char>; PredicateT = boost::algorithm::detail::is_classifiedF]’: /usr/include/boost/algorithm/string/trim.hpp:343:49: required from ‘SequenceT boost::algorithm::trim_copy(const SequenceT&, const std::locale&) [with SequenceT = std::basic_string_view<char>]’ t0.cpp:11:19: required from here /usr/include/boost/algorithm/string/trim.hpp:324:17: error: invalid conversion from ‘boost::range_detail::extract_const_iterator<std::basic_string_view<char>, true>::type’ {aka ‘const char*’} to ‘std::basic_string_view<char>::size_type’ {aka ‘long unsigned int’} [-fpermissive] 324 | TrimEnd | ^~~~~~~ | | | boost::range_detail::extract_const_iterator<std::basic_string_view<char>, true>::type {aka const char*} In file included from /usr/include/c++/11/bits/basic_string.h:48, from /usr/include/c++/11/string:55, from /usr/include/boost/algorithm/string/std/string_traits.hpp:15, from /usr/include/boost/algorithm/string/std_containers_traits.hpp:19, from /usr/include/boost/algorithm/string.hpp:18, from t0.cpp:1: /usr/include/c++/11/string_view:137:56: note: initializing argument 2 of ‘constexpr std::basic_string_view<_CharT, _Traits>::basic_string_view(const _CharT*, std::basic_string_view<_CharT, _Traits>::size_type) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_string_view<_CharT, _Traits>::size_type = long unsigned int]’ 137 | basic_string_view(const _CharT* __str, size_type __len) noexcept | ~~~~~~~~~~^~~~~ -- Olaf

2 1

VS2022 release date is Nov 8
by Peter Dimov 30 Oct '21

30 Oct '21

The Visual Studio 2022 (msvc-14.3) release date is Nov 8, which is right in the middle of our beta master freeze (Nov 3 - Nov 10). Since VS2022 is now RC2, which means that it won't change much if at all, we probably need to start testing our libraries with it now, so that the issues are ironed out before 1.78 beta.

9 12

The deadline for new libraries and breaking changes in Boost 1.78.0 is Friday, October 29
by Marshall Clow 27 Oct '21

27 Oct '21

Sorry for the late notice; the deadline was supposed to be today, but I'm extending it to Friday. See https://www.boost.org/development/index.html <https://www.boost.org/development/index.html> for the full calendar Next deadline: Boost 1.78.0 closed for beta Wednesday, Nov 3, 2021 — The Release Managers

1 0

Header-only Boost.System
by Ashish Singh 25 Oct '21

25 Oct '21

Hi All, In my application, I'm trying to use Boost ASIO via boost 1.66 and defining the following two macros in the Makefile. Basically trying to use the header-only approach. CFLAGS += \ -DBOOST_ERROR_CODE_HEADER_ONLY \ -DBOOST_SYSTEM_NO_DEPRECATED But then I came across this thread: https://lists.boost.org/Archives/boost/2017/10/239106.php "In header only mode, multiple instances may appear and thus no longer be proper singletons. Stuff breaks in this situation, badly." Is the above applicable to 1.66 too?How can I safely use the header-only approach in boost 1.66? Thanks,Ashish

2 8