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

Preview Site Link for Boost Website Feedback
by Louis Tatta 13 Feb '24

13 Feb '24

In my last email, I forgot to include the preview link for the new Boost website. Here it is: https://www.preview.boost.org/ <http://preview.boost.org>. Please take a look and report any feedback or issues on our GitHub page: https://github.com/cppalliance/temp-site/issues. Thanks for your help. Louis C++ Alliance

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Should boost::core::string_view be made public?
by Дмитрий Архипов 08 Feb '24

08 Feb '24

boost::core::string_view is a string_view implementation that (unlike boost::string_view from Utility) can interconvert with std::string_view. This functionality was necessary for Boost.JSON to drop the standalone mode, because people who have access to C++17 prefer to use std::string_view wherever they can. At the time there was no consensus on whether the type should be made public. Now in addition to Boost.JSON the type is also used at least by Boost.URL. And recently added Charconv is also using it. So, I want to raise the question again: should we make the type public and refer to it directly in our libraries' docs, rather than considering it an implementation detail?

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Re: [boost] [Scope] Peer review conclusion
by Andrey Semashev 06 Feb '24

06 Feb '24

On 2/6/24 22:29, Дмитрий Архипов wrote: > Looks good to me. I consider the review conditions satisfied. Thank you Dmitry. And especially for taking the time to review the documentation and point out errors. > пн, 5 февр. 2024 г. в 03:47, Andrey Semashev <andrey.semashev(a)gmail.com>: > >> >> On 1/15/24 22:50, Дмитрий Архипов via Boost wrote: >>> Dear Boost community, the formal review of Boost.Scope has taken place >>> between 26th of November and 5th of December of the previous year. I >>> have received 5 reviews in total, including 4 here on the mailing list >>> and 1 on Reddit. Two of the reviews recommended unconditional, and 3 >>> conditional acceptance. The >>> reviews came from: >>> - Klemens Morgenstern, >>> - Janko Dedic, >>> - Julien Blanc, >>> - David Sankel, >>> - /u/jonesmz on Reddit. >>> >>> Also, several people have given insightful comments but did not provide a >>> review. I would like to thank all of the people who took their time to write >>> reviews or participate in the discussions. Your effort was very important and >>> valuable. >>> >>> The outcome of the review is that Boost.Scope is ACCEPTED with several minor >>> CONDITIONS. >>> >>> 1. noexcept specification on destructors of scope guards should be properly >>> documented. Andrey has already commented that the technical hurdle that >>> prevented it was eliminated. >>> >>> 2. There should be a good motivating example for scope_success. There was a lot >>> of comments regarding scope_success and its seeming uselessness. Without a >>> good example I see the same pattern occurring with future users. >>> >>> 3. The examples should better describe what they are trying to achieve. Several >>> comments about examples suggested incorrect changes, which signals that readers >>> failed to understand them. >>> >>> After a lot of consideration I decided against requesting the author to remove >>> unique_resource and related functionality from the library. While several >>> reviewers wanted a more "concise" library, all noted that the component is >>> useful. >>> >>> One last thing I wanted to point out is that all reviewers and most commenters >>> were adamant that compatibility with the Technical Specification on which this >>> library was initially based should not be a goal. In fact, Andrzej Krzemienski >>> even noted that such compatibility has prevented him from adequately evaluating >>> the library on its own merit. In my opinion this should be a sign to all of us >>> that people prefer better APIs over standard APIs. I recommend Andrey to >>> re-evaluate those parts of the library's APIs that he copied from the TS and >>> potentially pick better names for member functions. >>> >>> Thanks to Andrey for submitting this library to Boost. And thanks again to the >>> reviewers and everyone who provided feedback, who ultimately made this review >>> possible. >> >> I have updated the library according to review comments and conditions. >> To specifically address the acceptance conditions: >> >> 1. Noexcept specifications for destructors are now present in the docs. >> For example: >> >> https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/defer_guar… >> https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_exit… >> https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/unique_res… >> >> The fix for the BoostBook stylesheets is currently in develop. >> Hopefully, it will get merged to master soon. >> >> 2. I have added an example showing usage of all three conditional scope >> guards, including scope_success, here: >> >> https://lastique.github.io/scope/libs/scope/doc/html/scope/scope_guards.htm… >> >> The example is based on the one I posted during the review. >> >> 3. I have added more comments to some examples, as well as the >> discussion around them. For example, the examples on the front page are >> better commented now: >> >> https://lastique.github.io/scope/libs/scope/doc/html/index.html >> >> Some examples were modified or completely rewritten. For example, the >> locked_write_string was modified to reduce code duplication: >> >> https://lastique.github.io/scope/libs/scope/doc/html/index.html >> >> The leading example for unique_resource was rewritten: >> >> https://lastique.github.io/scope/libs/scope/doc/html/scope/unique_resource.… >> >> And a new example for unique_resource was added on the front page: >> >> https://lastique.github.io/scope/libs/scope/doc/html/index.html >> >> There are many more additions and modifications than I can mention here. >> >> >> There were also changes that were requested by reviewers or were the >> result of the discussion. The changelog here lists most of the changes: >> >> https://lastique.github.io/scope/libs/scope/doc/html/scope/changelog.html >> >> To mention the most prominent changes: >> >> * BOOST_SCOPE_FINAL was renamed to BOOST_SCOPE_DEFER and scope_final to >> defer_guard. >> * The `release()` member of scope guards was removed. `set_active()` is >> still present and is the way to activate and deactivate scope guards. >> * Added `operator bool()` to `unique_resource`. >> * Added a C++17 `unallocated_resource` class template that simplifies >> declaration of resource traits when all unallocated resource values can >> be listed. Along with the recently added to Boost.Core `functor` >> template, this can significantly reduce the amount of code one needs to >> write to declare a `unique_resource`. For example, a `unique_resource` >> for Windows handles could be declared like this: >> >> unique_resource< >> HANDLE, >> functor< CloseHandle >, >> unallocated_resource< INVALID_HANDLE_VALUE, (HANDLE)NULL > >> > handle; >> >> https://lastique.github.io/scope/libs/scope/doc/html/scope/unique_resource.… >> https://www.boost.org/doc/libs/develop/libs/core/doc/html/core/functor.html >> >> * `unique_resource` now enforces requirements on the resource traits >> with static asserts rather than falling back to the "no resource traits" >> mode of operation. >> * `unique_resource` no longer supports the "reduced" resource traits, >> where the traits were only used to customize the default resource value >> but not to distinguish allocated and unallocated resource values. >> * Added documentation sections discussing differences with the Library >> Fundamentals TS: >> >> https://lastique.github.io/scope/libs/scope/doc/html/scope/scope_guards.htm… >> https://lastique.github.io/scope/libs/scope/doc/html/scope/unique_resource.… >> >> * On the front page, removed comparison with Boost.ScopeExit from the >> table. There is a separate section for it: >> >> https://lastique.github.io/scope/libs/scope/doc/html/scope/scope_guards.htm… >> >> Also added another row to the table that shows explicit deactivation of >> the scope guards by calling `set_active(false)`. >> >> * There is now a section discussing caveats of capturing variables by >> reference in scope guards: >> >> https://lastique.github.io/scope/libs/scope/doc/html/scope/scope_guards.htm… >> >> There are probably other changes that I forgot to mention. >> >> >> Dmitry, please let me know if you consider the review conditions >> satisfied or if there needs to be done something more. >> >> If everything's fine, what needs to be done to move the library into >> boostorg? >>

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Re: [boost] critical bugs in charconv
by g.peterhoff＠t-online.de 05 Feb '24

05 Feb '24

> So what's your point? Another example. I had asked for a TypeTrait is_integer and also supplied code for it (https://github.com/boostorg/type_traits/issues/186). The point is that is_integer only returns integer (no character, no bool). John immediately closed my request "We are not responsible for that". Instead of admitting a mistake (of course I make some myself) and saying "we forgot/didn't think of it, we'll do it", the only answer is "we don't care". That's thinking from the wallpaper to the wall. As I said, boost used to be progressive, but now when you make a suggestion, all you get is "We're not responsible for that/we're not interested in that/we might have to change something that's not possible" And this even with such a simple TypeTrait. Single file. No dependencies. And on the other hand, libraries with the most severe buffer overflows (charchonv) are included, where obviously no tests are carried out at all.

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Re: [boost] critical bugs in charconv
by g.peterhoff＠t-online.de 05 Feb '24

05 Feb '24

> So what's your point? a) boost/math/policies/error_handling.hpp manual name_of, although it would be no problem to add a simple nameof in boost/core/demagle.hpp: template <typename Type> inline std::string nameof() { return demangle(typeid(Type).name()); } b) boost/math/policies/policity.hpp manual "variadic templates" c) boost.convert (apart from the fact that this library is unusable due to its design) - no C++23 FP types - no (unsigned)__int128 - no __float128 These are just the things that came to my mind. The whole design and supported types of boost is stuck 25 years ago. As I said, I'm grateful that boost made C++11 possible. But since then you are stuck at this level and changes are *not* welcome.

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critical bugs in charconv
by g.peterhoff＠t-online.de 05 Feb '24

05 Feb '24

Hello Matt, Sorry for submitting a bug report this way. (Having problems with my GitHub account at the moment). Code: Attachment (gcc 13.2 -std=gnu++23 -O3 -Wall -fanalyzer) Errors (normal) - Missing sign - Hex exponent is wrong - Hex is completely wrong - Accuracy is not correct - Error code deviates from the standard ... The backup functions via (quadmath)snprintf do not work. Errors (critical) - If the buffer is too small (e.g. set the array size to 3) there are a lot of buffer overflows. Especially with value ±nan/±inf. The functions should therefore always be structured in the same way: Auxiliary function inline constexpr bool is_valid_range(const char*const first, const char*const last) noexcept { return (first!=nullptr && last!=nullptr) ? first < last : false; } Pseudocode to_chars(...) // FP { to_chars_result result{last, std::errc::value_too_large}; if (is_valid_range(first, last)) [[likely]] { const size_t size = size_t(last - first); if (inf or nan) [[unlikely]] { if (size is large enough) { copy the string values into the range result = ...; Here you could also use #define to specify whether the string values are compatible with the standard or not. "±inf", "±nan" or https://develop.charconv.cpp.al/#to_chars_usage_notes_for_to_chars_for_floa… } } else { convert, detail::implemantation(first, size, ...) result = ...; } } return result; } to_chars(...) // INT { to_chars_result result{last, std::errc::value_too_large}; if (is_valid_range(first, last)) [[likely]] { const size_t size = size_t(last - first); convert, detail::implemantation(first, size, ...) result = ...; } return result; } This can be achieved with templates and typetraits: FP boost::is_floating_point still does not contain any C++23 types. template <typename Type> BOOST_NOINLINE typename std::enable_if<std::is_floating_point<Type>::value, to_chars_result>::type to_chars(char*const first, char*const last, const Type value, const chars_format format, const int precision) noexcept; template <type name Type> BOOST_NOINLINE typename std::enable_if<std::is_floating_point<Type>::value, to_chars_result>::type to_chars(char*const first, char*const last, const Type value, const chars_format format) noexcept; INT (boost)is_integer is unfortunately still missing. template <type name Type> BOOST_NOINLINE typename std::enable_if<boost::is_integer<Type>::value, to_chars_result>::type to_chars(char*const first, char*const last, const Type value, const int base = 10) noexcept; regards Gero

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[Scope] Peer review conclusion
by Дмитрий Архипов 05 Feb '24

05 Feb '24

Dear Boost community, the formal review of Boost.Scope has taken place between 26th of November and 5th of December of the previous year. I have received 5 reviews in total, including 4 here on the mailing list and 1 on Reddit. Two of the reviews recommended unconditional, and 3 conditional acceptance. The reviews came from: - Klemens Morgenstern, - Janko Dedic, - Julien Blanc, - David Sankel, - /u/jonesmz on Reddit. Also, several people have given insightful comments but did not provide a review. I would like to thank all of the people who took their time to write reviews or participate in the discussions. Your effort was very important and valuable. The outcome of the review is that Boost.Scope is ACCEPTED with several minor CONDITIONS. 1. noexcept specification on destructors of scope guards should be properly documented. Andrey has already commented that the technical hurdle that prevented it was eliminated. 2. There should be a good motivating example for scope_success. There was a lot of comments regarding scope_success and its seeming uselessness. Without a good example I see the same pattern occurring with future users. 3. The examples should better describe what they are trying to achieve. Several comments about examples suggested incorrect changes, which signals that readers failed to understand them. After a lot of consideration I decided against requesting the author to remove unique_resource and related functionality from the library. While several reviewers wanted a more "concise" library, all noted that the component is useful. One last thing I wanted to point out is that all reviewers and most commenters were adamant that compatibility with the Technical Specification on which this library was initially based should not be a goal. In fact, Andrzej Krzemienski even noted that such compatibility has prevented him from adequately evaluating the library on its own merit. In my opinion this should be a sign to all of us that people prefer better APIs over standard APIs. I recommend Andrey to re-evaluate those parts of the library's APIs that he copied from the TS and potentially pick better names for member functions. Thanks to Andrey for submitting this library to Boost. And thanks again to the reviewers and everyone who provided feedback, who ultimately made this review possible.

3 5

[charconv] Review Results and Report
by Christopher Kormanyos 02 Feb '24

02 Feb '24

Dear Boost Community, The review of the proposed Boost.Charconv is finished It took place 15-25 January 2024. REVIEW RESULT ----------------------------- The result is Boost.Charconv is unconditionally * ACCEPTED * into Boost. Thank you Matt. Boost.Charconv will enrich Boost and surely be used vigorously. REVIEW REPORT ----------------------------- The review tally is: * 1 Conditional ACCEPT * 4 ACCEPT * 1 Positive Document Review ---------------------------- = 5 ACCEPT, since the single condition has already been satisfied in develop branch. My Comments and Descriptions below are based on limited knowledge and my subjective interpretations. Please correct, add, modify these (and to these) as needed. * Comments: The review atmosphere was highly productive and excellent. Reviews and contributions featured deep technical content and detail. Fact-based statements combined with experienced-based opinions were provided. There was great strength of expression and clarity. Yet there was mutual respect and fairness, even in the course of lively debate. * Descriptions: Ultimately there were three areas receiving the most debate. For background, see references below. 1) The library needs to allocate. Among other conversions, Boost.Charconv handles conversion of floating-point values to chars. Edge-cases may require hundreds or even thousands of bits. * Consensus: Handle the required memory needed, as done, with low-level C-LIB malloc. But do describe this decision with greater depth of clarity in the docs. 2) The project makes use of a variety of methods, including some table-driven methods. One example is RYU (see [1]). A quick glance at Fig. 4 in [1], for instance, reveals the need for relatively large, constant-valued tables. Largescale tables, combined with the C++11 design goal formed a clear indication to produce a compiled library (as opposed to a header-only one). * Consensus: Compiled-library is sound and viable. Tables (especially in constexpr-context) might bloat or not even work in some language-standards environments. Some commenters, however, seemed subjectively to disapprove of this consensus, feeling that header-only offers the best chances at friction-free setup and convenient portability. Other commenters revealed a sense that compiled libraries are gaining traction in the industry. They feel that this is because the community, their available tools, language-skills, specifications, compilers, CI, VMs, etc. have matured significantly and continue to mature. Thereby they embrace a perceived future-oriented trend that views client-builds to be uncomplicated. There were no blockers on the consensus. 3) The top-level interface differs from that of std-<charconv> in points such as overloads and error-handling. Whereas some details are not even fully hashed-out in the Standard. * Consensus: Weigh known opinions and decide interface details based on unbiased majority. My current understanding is: Offer two drop-ins for from_chars, with the caveat that one should provide better error-handling. REVIEW ACKNOWLEDGMENTS ----------------------------- Thanks again, Matt for Boost.Charconv. Many thanks to our expert reviewers, commenters and watchers. Your contributions keep Boost excellent! Kindest regards, Christopher Kormanyos Boost.Charconv Review Manager * References: [1] Ulf Adams, "RYU: fast float-to-string conversion", ACM SIGPLAN Notices, Volume 53, Issue 4, pp 270–282 (ACM 2018) [2] "Number Parsing at a Gigabyte per Second", Daniel Lemire's Blog, https://lemire.me/blog/2021/01/29/number-parsing-at-a-gigabyte-per-second/ [3] https://github.com/lemire/fast_double_parser

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[charconv] Review Results and Report
by Christopher Kormanyos 02 Feb '24

02 Feb '24

Dear Boost Community, The review of the proposed Boost.Charconv is finished It took place 15-25 January 2024. REVIEW RESULT ----------------------------- The result is Boost.Charconv is unconditionally * ACCEPTED * into Boost. Thank you Matt. Boost.Charconv will enrich Boost and surely be used vigorously. REVIEW REPORT ----------------------------- The review tally is: * 1 Conditional ACCEPT * 4 ACCEPT * 1 Positive Document Review ---------------------------- = 5 ACCEPT, since the single condition has already been satisfied in develop branch. My Comments and Descriptions below are based on limited knowledge and my subjective interpretations. Please correct, add, modify these (and to these) as needed. * Comments: The review atmosphere was highly productive and excellent. Reviews and contributions featured deep technical content and detail. Fact-based statements combined with experienced-based opinions were provided. There was great strength of expression and clarity. Yet there was mutual respect and fairness, even in the course of lively debate. * Descriptions: Ultimately there were three areas receiving the most debate. For background, see references below. 1) The library needs to allocate. Among other conversions, Boost.Charconv handles conversion of floating-point values to chars. Edge-cases may require hundreds or even thousands of bits. * Consensus: Handle the required memory needed, as done, with low-level C-LIB malloc. But do describe this decision with greater depth of clarity in the docs. 2) The project makes use of a variety of methods, including some table-driven methods. One example is RYU (see [1]). A quick glance at Fig. 4 in [1], for instance, reveals the need for relatively large, constant-valued tables. Largescale tables, combined with the C++11 design goal formed a clear indication to produce a compiled library (as opposed to a header-only one). * Consensus: Compiled-library is sound and viable. Tables (especially in constexpr-context) might bloat or not even work in some language-standards environments. Some commenters, however, seemed subjectively to disapprove of this consensus, feeling that header-only offers the best chances at friction-free setup and convenient portability. Other commenters revealed a sense that compiled libraries are gaining traction in the industry. They feel that this is because the community, their available tools, language-skills, specifications, compilers, CI, VMs, etc. have matured significantly and continue to mature. Thereby they embrace a perceived future-oriented trend that views client-builds to be uncomplicated. There were no blockers on the consensus. 3) The top-level interface differs from that of std-<charconv> in points such as overloads and error-handling. Whereas some details are not even fully hashed-out in the Standard. * Consensus: Weigh known opinions and decide interface details based on unbiased majority. My current understanding is: Offer two drop-ins for from_chars, with the caveat that one should provide better error-handling. REVIEW ACKNOWLEDGMENTS ----------------------------- Thanks again, Matt for Boost.Charconv. Many thanks to our expert reviewers, commenters and watchers. Your contributions keep Boost excellent! Kindest regards, Christopher Kormanyos Boost.Charconv Review Manager * References: [1] Ulf Adams, "RYU: fast float-to-string conversion", ACM SIGPLAN Notices, Volume 53, Issue 4, pp 270–282 (ACM 2018) [2] "Number Parsing at a Gigabyte per Second", Daniel Lemire's Blog, https://lemire.me/blog/2021/01/29/number-parsing-at-a-gigabyte-per-second/ [3] https://github.com/lemire/fast_double_parser

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