November 2019 - Boost - lists.preview.boost.org

What happened to Boost.Nowide?
by Alexander Grund 08 Jan '20

08 Jan '20

Hi, I'm a user of (a fork of) Boost.Nowide and already fixed some issues I found and was looking into getting them upstream. I also wanted to know, if it is finally in Boost. Unfortunately this does not seem to be the case. I found https://lists.boost.org/Archives/boost//2017/06/236475.php which accepted it into Boost. This is from mid-2017 and nothing has happened since. Does anyone know what the status of Boost.Nowide is? It seems the filestream parts are now incorporated into Boost.FileSystem. So it seems only cin/cout/cerr, the args wrapper and the C-functions (fopen, ...) are missing. Especially the first 2 are very useful in writing cross-platform code. Might those be integrated into some other Boost Library? Thanks, Alex

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Re: [boost] Jason is getting MARRIED!
by Bjorn Reese 20 Dec '19

20 Dec '19

On 11/16/19 7:09 PM, Vinnie Falco via Boost wrote: > My JSON library is going to propose to Boost soon, is there anyone who > might be willing and able to function in the role of review manager? Before we get to that point, there are some questions that the community should address. These days there are a huge number of JSON libraries out there. Some focus on features (e.g. binary JSON or JSONPath), others on performance, and others on user-friendliness. What competitive edge should a potential Boost JSON library offer? Which use cases should a potential Boost JSON library support? Should the library work seemlessly with standard algorithms? Should it be possible to create parser combinators? Should there be a JSON archive for Boost.Serialization? Should it replace parts of Boost.PropertyTree? PS: On a procedural note, you need an endorsement of the library before seeking a review manager.

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Interest in a C++20 Unit Testing Framework?
by Krzysztof Jusiak 10 Dec '19

10 Dec '19

Hi, I was wondering whether there is any interest in exploring a C++20 single header/single module, macro-free Unit Testing Framework with no dependencies? Github: https://github.com/boost-experimental/ut Additional links: - Try it online: https://godbolt.org/z/uVDxkW - Benchmarks: https://github.com/boost-experimental/ut#benchmarks - How it works?: https://github.com/boost-experimental/ut#how-it-works Thanks, Kris

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[release] 1.72.0 post-beta merges
by Michael Caisse 08 Dec '19

08 Dec '19

The master branch is is now open for post-beta merges, but only as described in the Post-Beta Merge Policy. See <https://github.com/boostorg/boost/wiki/Releases%3A-Beta-Merge-Policy>

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[nowide] Future
by Artyom Beilis 07 Dec '19

07 Dec '19

The nowide library was reviewed and accepted into Boost almost 3 years ago. I implemented most of fixes required under Review Fixed branch https://github.com/artyom-beilis/nowide/tree/reviewfixes Unfortunately I don't have any capacity to do maintenance for it on all various platforms: MSVC, mingw. cygwin etc mostly because virtually I don't develop on Windows and any time I need to go there I need to figure it out from the beginning (installations, environment, msvc) and I don't even have windows machine in my hands (all done in VM) I realized that I'm not windows developer any more and it would be impossible for me to complete the mission of maintaining the code mostly due to personal reasons and lack of development resources. I deeply regret wasting the time and effort of so many boost developers who invested to review. I understand that it is highly desired library but I just can get the job done I seek for your advice. Do I need to seek for an another maintainer or withdraw the library entirely? Once again sorry for disappointing the community and people who were invested in this library. Artyom Beilis

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[review][fixed_string] FixedString review starts Nov 25
by Joaquin M López Muñoz 05 Dec '19

05 Dec '19

The Boost formal review of Krystian Stasiowski and Vinnie Falco's FixedString library will take place November 25 - December 4, 2019. This is an early call for you to consider participating in the review. Feedback and constructive criciticism from experts and not-so-experts alike is very much welcome. FixedString being a relatively small and straightforward library, you will find it very easy to familiarize yourself with it and contribute back to the community. FixedString provides a dynamically resizable string of characters with compile-time fixed capacity and contiguous embedded storage in which the characters are placed within the string object itself. Its API closely resembles that of std::string. GitHub repository: https://github.com/18/fixed_string Online docs: https://18.github.io/doc/fixed_string If you feel like reviewing FixedString you can start now prepping --though I'd ask you to refrain from submitting actual reviews till Nov 25. Read the docs, download/fork the code, read/run it, maybe try integrating it into some project of yours, ask questions to the authors, preferrably on Boost or Boost Users mailing lists. The FixedString initiative arose from a very lively discussion within the community: https://lists.boost.org/Archives/boost/2019/09/246943.php , so I sincerely hope this review will be a fruitful, crowded one. Don't let me down! Best regards, Joaquín M López Muñoz Review manager for candidate Boost.FixedString

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[review][fixed_string] FixedString review starts today
by Joaquin M López Muñoz 04 Dec '19

04 Dec '19

The Boost formal review of Krystian Stasiowski and Vinnie Falco's FixedString library starts today November 25 and extends up to December 4. Description FixedString provides a dynamically resizable string of characters with compile-time fixed capacity and contiguous embedded storage in which the characters are placed within the string object itself. Its API closely resembles that of std::string. Repo and docs GitHub repository: https://github.com/18/fixed_string Online docs: https://18.github.io/doc/fixed_string Review questions Here are some questions you might want to answer in your review: - 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 what compiler? 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? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? I invite you to submit your review, either publicly to the developers or the users lists, or else, if for whatever reason you don't want to go public, directly to me. Thank you for investing your time on reviewing Krystian and Vinnie's work and for contributing to the advancement of Boost. Best regards, Joaquín M López Muñoz Review manager for candidate Boost.FixedString

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Error handling benchmarks: LEAF, Boost Outcome
by Emil Dotchevski 02 Dec '19

02 Dec '19

I wrote a benchmark program for LEAF and Boost Outcome. Here are the results: https://github.com/zajo/leaf/blob/master/benchmark/benchmark.md

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Fixed String review
by Phil Endecott 02 Dec '19

02 Dec '19

Dear All, Here is my review of the proposed Fixed String library. In summary I think this would be a useful thing to have in Boost, but there are a few issues with the code as it currently stands. This is based on studying the code and docs and the previous mailing list discussions in September; I haven't actually tried to use the library. Firstly regarding the name, I would much prefer static_string for consistency with boost::container::static_vector and with P0843. Note that static_vector was the preferred name in an LEWG poll, according to P0843. It's true that "static" is an ambiguous word that does not really convey what is different about this string, but then neither does "fixed" in my opinion; "fixed capacity" would, but just "fixed" sounds more like "immutable" to me. On the subject of P0843, it it worth reading as it contains some useful links and rationale: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0843r2.html Also a more recent r3 update and reference implementation: https://github.com/gnzlbg/static_vector Here are the features that I think are missing, in no particular order; apologies if some of this does exist but I've missed it: - Much more of it should be constexpr. See P0980R1. That mentions that some of char_traits needs to be constexpr as a prerequisite, but even without that things like size() and empty() can be constexpr. There is also a question of whether all of the elements must be initialised (to 0) by the ctor to be constexpr, which could be costly for a large but sparse container, though it does mean that subsequent push_back()s don't need to store terminators; I don't understand all the issues involved here. (I note a comment in the docs suggesting the lack of constexpr may be temporary.) - In the same vein, more of it should be noexcept - why aren't empty() and size() ? - You can add a specialisation for size 0 that turns it into an empty struct. - You can add a string literal operator"". - You can add std::hash overloads. There are various possibilities for what should happen if the capacity is exceeded, including throwing an exception, asserting, and allowing undefined behaviour. I'm not sure what I would really prefer though I think I'd be more likely to assert() than to throw. See P0843r2 again which discusses this. Regarding your deviations from std::string: operator+ has been omitted because you consider it's not possible to determine a reasonable return type; isn't it just size N+M ? Do you reject that just because it could end up rather large after a sequence of additions? I'd agree if it were N*M but not really for N+M. Have I missed something? You've chosen to return a string_view from substr(). I think that's a bit dangerous; code that does "auto a = s.substr(...)" could end up with a dangling view when s is a fixed string; this makes it more difficult than it should be to migrate from one string type to another, or to write generic code. Regarding the docs, it would be great if the reference could have some highlighting (e.g. bright red?) for the few places where it differs from std::string. My own use for this sort of string has often been to store very large numbers of small strings when total memory usage has been a concern. (A good example would be an textual ID code of some sort, like a postal code or an airport code etc.) For this case, the 8-byte overhead for the size_t length field is a concern; I'd like a static_string<6> to need only 8 bytes total. I suggested changing this to the minimum size needed to store values 0 to N in the previous email discussion, but that hasn't been implemented. My initial thought was that static_string should be implemented on top of boost::container::static_vector<char>. My rationale for that was that static_vector is well-established and doesn't need to be re-implemented, and that a string_facade that adapts a vector<char>-like interface into a string-like interface would be a useful component in its own right. (I've tried to write something like this myself, but it gets tedious very quickly writing out all of those special string methods.) But then I discovered that actually boost::container::static_vector is not implemented as a simple size,data[] pair; apparently it contains pointers to its own storage. So it isn't even trivially- copyable. Now that I know that, I wonder if what we really need is a low-storage-overhead static_vector "done properly" (like the P0843 reference implementation), with a string_facade to make static_string from static_vector<char>. On balance, my view is that this proposal is promising but not quite ready yet. I suggest that the authors should be asked to come back in a few months with a revised version. My preferred design would be an improved static_vector and a string_facade that converts it into a static_string, but if they don't want to do that then simply tidying up the constexpr, noexcept and hash issues would be minimally sufficient. Regards, Phil.

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[fixed_string] Why "fixed" rather than "static"?
by Andrzej Krzemienski 29 Nov '19

29 Nov '19

Hi Everyone, First, I would like to thank Vinnie and Krystian for writing and sharing the library. While this is not a review, I would like to share a thought about the choice of name. Given that we have static_vector, which seems to be doing a similar thing, why was this library called fixed_string rather than static_string? I note that name fixed_string has some potential to mislead the users as it might imply that it is the size that is fixed (like "a string that always stores 2-letter country codes"). I am not saying that the name choice is wrong. I would just want to see the rationale. Regards, &rzej;

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