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

CMake Announcement from Boost Steering Committee
by Jon Kalb 13 Aug '24

13 Aug '24

The libraries produced by the Boost community have had a greater impact on the way that the C++ community writes code than any other library implementation. The focus of the Boost community will always be on the libraries, but it is undeniable that we are dependent on and often limited by the infrastructure of our trade. Years ago, the move to Git was contentious; yet, it was required to improve development. In a similar vein our build system has become an impediment for many developers and users, existing and prospective. Therefore, we, the Steering Committee, announce to the Boost community our desire and intent to move Boost’s build system to CMake for users and developers alike. We are soliciting comments and proposals from the community to guide the process and the goals. Our desire is that the community can come to consensus by the end of the calendar year with a vision of supporting users and developers. We understand that the actual process of achieving the end goal will be long, time consuming, and not without its share of conflict. We also recognize that the Boost community is comprised of bright and passionate individuals that are eager to get involved and help get work done. The members of the Steering Committee have been encouraged by the discussions and activity surrounding CMake on the mailing lists over the years and know that many people have voiced visions. We hope that each of you rejoins the discussion to support this initiative and contributes to the common goal of improving Boost’s integration into the broader C++ ecosystem. For the Boost Steering Committee, Jon Kalb, Chair jonkalb(a)boost.org

49 199

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

4 16

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.

10 68

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

8 30

[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>

11 31

[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

6 10

[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

5 5

[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

11 39

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

3 4

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.

9 23

[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;

5 8

Re: [boost] [Boost-users] [review][fixed_string] FixedString review starts today
by Peter Dimov 29 Nov '19

29 Nov '19

> and yes, you can write code that will be correct if op+= doesn't check. Maybe you can, but I apparently can't. This is what I just wrote: void my_append( fixed_string<512> & s, std::string_view s1, std::string_view s2 ) { if( s.size() + s1.size() + s2.size() > s.max_size() ) throw std::length_error( "" ); s += s1; s += s2; } Is this correct? (Spoiler: no.)

2 2

Re: [boost] [Boost-users] [review][fixed_string] FixedString review starts today
by Peter Dimov 29 Nov '19

29 Nov '19

> https://godbolt.org/z/Z37Pmx > https://godbolt.org/z/CXHRKQ I forgot to maintain a 0 terminator in this sketch; it's even worse with it. .L5: add rax, 1 movzx ecx, BYTE PTR [rdx] cmp rax, 512 ja .L11 add rdx, 1 mov BYTE PTR [rdi+7+rax], cl mov BYTE PTR [rdi+8+rax], 0 mov QWORD PTR [rdi], rax cmp rsi, rdx jne .L5 https://godbolt.org/z/nhYZQY .L3: movzx ecx, BYTE PTR [rdx+rax] mov BYTE PTR [rdi+8+rax], cl add rax, 1 mov BYTE PTR [rdi+8+rax], 0 mov QWORD PTR [rdi], rax cmp r8, rax jne .L3 https://godbolt.org/z/pGJRWs

1 0

Re: [boost] [review][fixed_string] FixedString review starts Nov 25
by Peter Dimov 28 Nov '19

28 Nov '19

> Also, a synopsis section in the documentation might have been nice, to > allow one to see all the declarations in one place. (Admittedly, the main > header does serve that purpose somewhat.) I join the others in noting the pervasive lack of constexpr and noexcept. Even the default constructor isn't either. Can't think of a reason why it would throw. (The lack of constexpr is much easier to explain.) Also, Traits template parameters were wrong in C++98, and they remain wrong today, even though the committee has propagated that mistake into string_view.

2 1

Re: [boost] [Boost-users] [review][fixed_string] FixedString review starts today
by Peter Dimov 28 Nov '19

28 Nov '19

> I would "precondition" `op+=( char const (&)[ M ] )` (and op=) by failing > at compile time when M > N, because the size is known, but in > fixed_string's case, the size isn't known. No I wouldn't. :-) The size isn't known in this case either. It's better to diagnose_if the whole thing.

1 0

[STLInterfaces] only three operations?
by Andrzej Krzemienski 28 Nov '19

28 Nov '19

Hi, While the formal review of STLInterfaces has not yet started, some early feedback may be of help. The idea to implement relational operators from binary operator- for random_access_iterator looks too clever for me. Maybe this deserves a mention in the documentation it is from operator- that the library will generate all relational ops. For non-contiguous random_access_iterators (like in deque) it might be suboptimal to do it this way: a directly provided operator== might be faster than the one synthesized from operator-. Of course, I can provide the 6 relops operators myself, but I could have only 2 if the facade were capable of generating operator!= from operator== (and similar). Could operator!= for random_access_iterator be generated from operator!= ? Regards, &rzej;

3 5

[FixedString] Deniz' review
by Deniz Bahadir 27 Nov '19

27 Nov '19

This is my review of Krystian Stasiowski and Vinnie Falco's FixedString library. The important question and its answer upfront: - Do you think the library should be accepted as a Boost library? I think it should be ACCEPTED into Boost. It is a very small (almost trivial) library and in the beginning I was not sure if it really should go into Boost. However, for me it looks like a useful building-block, so I vote ACCEPT. And if I remember correctly Vinnie said he is already having some other libraries using it which he wanted to propose for Boost later, so there seem to be some real use-cases for it already. Besides, Boost already has some other smaller building-block libraries, so FixedString should be in good company. On a side-note: It would be helpful for the Boost library documentation overview (e.g. https://www.boost.org/doc/libs/1_71_0/) to allow more views/sort-orders for listing available Boost libraries than the views/sort-orders which are already there. (Having "building-blocks" and especially "newer C++ standard features for C++03" or similar "standard compatibility" categories for the Boost libraries comes to mind.) OK, now back to the review. - What is your evaluation of the design? The overall design looks straight forward. `boost::fixed_string`'s API resembles that of `std::string` and only the internal representation differs largely. This looks like the correct design for the aimed purpose of this library (to provide a dynamically resizable string with compile-time fixed capacity.) - What is your evaluation of the implementation? The implementation looks solid and also straight forward. However, I have some remarks to make which you can read further down in this email. - What is your evaluation of the documentation? The documentation is quite small, except for the reference section. This, however, should be fine considering the very simple and small focus which FixedString has. Regarding the "Iterators" section, it was not clear to me on first read for which string type the iterators are invalidated when moving/swapping. I think, `boost::fixed_string` is meant and not `std::string`, but that was not obvious from first read and the wording should probably be improved there to be unambiguous. (Maybe make this clear by speaking of "FixedString" or "fixed_string" instead of just "string".) - What is your evaluation of the potential usefulness of the library? For the use-cases mentioned in the "Motivation" section of the documentation it seems to be useful. All other use-cases I could think of are specializations of the mentioned use-cases. - Did you try to use the library? With what compiler? Did you have any problems? No, I have not tried to use the library. However, I am curious to know if Boost.String_Algorithms can operate on `boost::fixed_string`, too. If not, it would be nice for the code of FixedString and/or Boost.String_Algorithms to be modified in such a way that they can inter-operate with each other. - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? I read the documentation, but the reference section I merely visually scanned through. (I assume, there are no mistakes in it, as they mainly resemble the API of `std::string`.) I looked at the implementation but did not look at all function implementations in all depths. I, however, looked at the CMakeLists.txt file, too, and have some remarks for it (see below). Overall, I probably spent about 1.5 hours for the review, not including the writing of this email. - Are you knowledgeable about the problem domain? Only as far as it gets if you are a general user of `std::string`. I have the following additional remarks: * `boost::to_fixed_string` / `boost::detail::max_digits`: - Is the returned `boost::fixed_string` type of `boost::to_fixed_string` large enough to also hold the (plus) sign of an unsigned integer (if a user might want to append it later)? (Reading the comment and implementation of `boost::detail::max_digits` I assume the answer is yes.) Maybe, make this clear in its reference documentation. * "boost/fixed_string/config.hpp": - At the top of this file we have `#define BOOST_FIXED_STRING_USE_BOOST`, which therefore makes all following conditional definitions always use Boost equivalents of standard library types internally. Is it really desired to have it hard-coded here? Shouldn't the user decide if s/he wants to use Boost compatibility types instead of the ones coming from the standard library? * Filenames - I do not really like, that all files have the same name "fixed_string.hpp". There is the main one in "boost/fixed_string", another one in "boost/fixed_string/detail" and a third one in "boost/fixed_string/impl". I would prefer these files having some (at least slightly) different names. * "CMakeLists.txt": - This CMakeLists.txt file is written in Traditional CMake (old style CMake) although requiring CMake 3.5.1 which knows how to handle Modern CMake. You should consider using Modern CMake instead. - You should leave `CMAKE_CXX_FLAGS` untouched. It is for the user of the library, not for the developer! - Similar, set requirements for a specific minimum required C++ version using the `CXX_STANDARD` property instead of hard-coding it into `CMAKE_CXX_FLAGS`. - You should probably replace usage of `include_directories` with `target_include_directories` on the specific targets. - Similar for `add_definitions` and `link_directories`. - Using `file(GLOB...)` for globbing sources is dangerous and CMake might not always realize that some sources have changed. (see note at: https://cmake.org/cmake/help/latest/command/file.html#glob) - In general, I am not sure if that CMakeLists.txt file should have been part of the review, but I recommend to provide a useful and more modern one if this is going to become a part of Boost, too. Best regards, Deniz

6 10

Suggested policy for dropping C++03 support in Boost libraries
by Peter Dimov 26 Nov '19

26 Nov '19

We need a policy on phasing out C++03 support in Boost. C++03 support is holding us back. It impedes development, increases maintenance costs, increases dependencies, and increases compilation times. Library authors and maintainers need to have an approved mechanism for dropping C++03 support in their libraries. The suggested way forward is to allow library authors to declare C++03 support deprecated via a notice in the documentation and a message issued at compile time, then be allowed to drop C++03 support no earlier than three Boost releases later. For instance, a library may declare C++03 support deprecated in Boost 1.73, and drop it no earlier than in Boost 1.76. More at https://pdimov.github.io/articles/phasing_out_cxx03.html.

12 21

Beginner's guide
by Siddhartha Sen 26 Nov '19

26 Nov '19

Could anyone help me get started? This is my first time contributing to open source. I am proficient with C++11 and C++14(Not so much with 17 though). Also, I am not sure whether this is useful or not but I have a very keen interest in algorithms and problem solving techniques in general. Any help would be appreciated.

3 2

Re: [boost] [Boost-users] Interest in a C++20 Unit Testing Framework?
by Krzysztof Jusiak 25 Nov '19

25 Nov '19

Thanks for your valuable feedback. I added initial versions of tutorial and user-guide to README. It's not ideal yet but it's a start. * https://github.com/boost-experimental/ut#tutorial * https://github.com/boost-experimental/ut#user-guide I also updated benchmarks with Boost.Test-1.71.0 (static library). I didn't add Boost.LightweightTest though as it's just assertions (no tests/suites/etc...) so it makes it difficult to compare due to missing features. * https://github.com/boost-experimental/ut#benchmarks I hope that helps a bit. Thanks again, Kris On Fri, Nov 22, 2019 at 1:17 AM Richard Hodges via Boost-users < boost-users(a)lists.boost.org> wrote: > It looks very interesting. The idea of not using macros is very appealing > to me. > > From looking at the examples, I get the feeling of "I could probably use > this". > > However, as the other commenters have mentioned, without a tutorial and > full reference it's difficult to judge whether it's ready for use in > production. > > Are there plans to develop this? > > > > > On Thu, 21 Nov 2019 at 16:24, Krzysztof Jusiak via Boost-users < > boost-users(a)lists.boost.org> wrote: > >> 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 >> _______________________________________________ >> Boost-users mailing list >> Boost-users(a)lists.boost.org >> https://lists.boost.org/mailman/listinfo.cgi/boost-users >> > > > -- > Richard Hodges > hodges.r(a)gmail.com > office: +442032898513 > home: +376841522 > mobile: +376380212 > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > https://lists.boost.org/mailman/listinfo.cgi/boost-users >

2 2

[review] [STLInterfaces] STLInterfaces review starts December 10
by Barrett Adair 23 Nov '19

23 Nov '19

The Boost formal review of Zach Laine's STLInterfaces library will take place December 10 - 19, 2019. Please consider participating in this review. The success of Boost depends on our robust library review process. STLInterfaces is a C++14 library targeting ISO standardization. The following templates are provided, all C++20-friendly: 1. iterator_interface - a modern version of the iterator_facade and iterator_adaptor parts of Boost.Iterator 2. view_interface - a pre-C++20 implementation of C++20's eponymous feature 3. container_interface - a tool to eliminate boilerplate when writing new containers. Code: https://github.com/tzlaine/stl_interfaces Docs: https://tzlaine.github.io/stl_interfaces/doc/html/index.html Thanks, Barrett Adair

1 0

icl
by Andreas Fislage 22 Nov '19

22 Nov '19

Hello all, I am new here... I recently used icl and ran into a rather surprising behavior: Assertion failed: (numeric_minimum<domain_type, domain_compare, is_numeric<domain_type>::value> ::is_less_than_or(upper(object), is_right_closed(object.bounds())) ), file ...\boost\icl\concept\interval.hpp, line 438 This is the code to produce the problem: #include <boost/icl/discrete_interval.hpp> int main() { boost::icl::discrete_interval<size_t> x{0, 0}; boost::icl::discrete_interval<size_t> y{0, 1}; boost::icl::contains(x, y); } Note that the assertion fails only with size_t not with int. What could be reason for this?

1 0

Boost serialization (bug?) issue with MSVC, with vector<shared_ptr> in several libraries
by Nicolas Guillot 22 Nov '19

22 Nov '19

We use boost serialization in ours projects, both on linux (gcc) and Windows. We encounter a problem only on Windows (for "every" versions of Windows (7 and 10) and of MSVC: Visual 2010 and 2015, ie. MSVC++ 10.0 _MSC_VER == 1600 or MSVC++ 14.0 _MSC_VER == 1900). *Here is the problem summarized*, but I need to give more details after: When I serialize a class - which have base class - and have 2 vector of shared_ptr of ClassB, with the same contents, and B inherits from the same base class the serialization works, but the deserialization doesn't ("input stream error"). The following image is here : https://i.stack.imgur.com/osoiF.png (if it's not displayed) [image: enter image description here] <https://i.stack.imgur.com/osoiF.png> Yes, it's very strange: - if I remove the base class, it works. - if I inline the serialization code (empty function) of the base class, it works. - if the 2 vectors don't have the same content, it works !! - if I register the ClassBase in the serialize method of ClassTest, it works. I.e.: // in ClassTest:template <class Archive>void serialize(Archive & ar, const unsigned int version) { ar.template register_type<ClassBase>(); ...} *Some details* *When it works* on linux, and when it works on Windows with ClassBase type registration in the archive, we have the same xml output. It's worth noting that: - boost_serialization is version 17 on Windows and 9 on linux (I didn't tried to update boost on linux yet). - On BaseClass xml tag, the tracking_level="1", so we have object_id. *And when it doesn't work* (once again: the serialization of ClassTest is OK, but cannot deserialized "input stream error"): - The main difference is in the serialization of ClassTest: the ClassBase part has no tracking_level. - However it's not the only cause, because if the vectors are differents (same 2 first items, and a third item in one vector), tracking_level of ClassBase in ClassTest part is "0". Last thing, if it can give you some clues: while we debugged our application, we noticed that the deserialization framework tries to deserialize a class into another. It makes me think the serialization framework is confused about the classe types identifications. Could it be a matter of dll linking? Of global static shared storage ? I've posted a visual studio solution here <https://1drv.ms/u/s!Aoy4ax0S3ZS5gkxv1UIvRUd32oVO?e=ACVi4c>. Thanks a lot for your help. And if any clarification is needed, I'm available of course !

2 3

[xpressive] Accept one line pull that's been outstanding for a couple years?
by Brian Kuhl 21 Nov '19

21 Nov '19

Hi Boost, We've been running nightly regression on this for years now at Wind River over a couple Boost releases. Any reason it can't be merged? https://github.com/boostorg/xpressive/pull/5 Thanks Brian

1 0

Re: [boost] Jason is getting MARRIED!
by julien.blanc＠tgcm.eu 21 Nov '19

21 Nov '19

"Vinnie Falco" vinnie.falco(a)gmail.com – 21 novembre 2019 15:29 > Yep, the bench program and input files are here: thanks. I'll try to compile it for raspberry pi and report the results here. > > A 200MB file would be a good start to see how the library deals with large files. > > I don't have a 200MB JSON file, and I have doubts that it would > provide much more information than what we have already. I'd also > prefer not to put a 200MB file into the repository. The goal of this > library is to be in the same ballpark as rapidjson, it doesn't try to > be the top performer (in fact, rapidjson achieves its performance by > making usability tradeoffs which are unsuited for vocabulary types). > > However if someone wants to run the bench program on a 200MB file or > any other custom inputs and report the results, that would be great! Just made the test, and the validator performs well (memory consumption is about the size of the file, which i is expected since the whole file is read in memory), while the printer memory usage was huge (i had to stop it, but it was at that time already eating more than 1Gbyte memory, which is not expected). Regards, Julien

2 1

istream_iterator_limited
by Frederick Gotham 21 Nov '19

21 Nov '19

[MODERATOR: I tried to post this a week ago, but for some reason the word SPAM was prefixed to the subject line and so it didn't show up on the GMane server. I don't think many people actually saw it.] - - - - WHY I NEEDED THIS: I wanted to open a file using "ifstream", and then I wanted to read 32 bytes from the file and feed them directly into boost::algorithm::hex. Unfortunately I couldn't do this because 'hex' takes two iterators [begin,end), and there's no alternative function "hex_n". So I had to read the file into a string first, and then pass the string to 'hex'. - - - - THE IDEA I CAME UP WITH: Open the file using "ifstream", and then use a special iterator that will stop reading from the file after 32 bytes, with syntax like this: ifstream logfile("log.txt"); hex( istream_iterator_limited<char>(logfile,32), istream_iterator_limited<char>(), g_some_global_container.begin() ); - - - - SAMPLE CODE: #include <cstddef> /* size_t */ #include <iterator> /* istream_iterator */ template <typename T> class istream_iterator_limited : public std::istream_iterator<T> { protected: std::size_t const m_limit; std::size_t m_current_count; public: /* Shorter names */ typedef std::istream_iterator<T> Base; typedef istream_iterator_limited<T> This; istream_iterator_limited(typename Base::istream_type &obj_stream, size_t const arg_limit) : Base(obj_stream), m_limit(arg_limit), m_current_count (1) { /* The initialiser list above does all the construction work */ } istream_iterator_limited(void) /* This gives the End-Of-Stream iterator */ : Base() , m_limit(0), m_current_count(1) { /* The initialiser list above does all the construction work */ } This &operator++(void) { if ( m_limit <= m_current_count ) { Base::operator=( Base() ); /* Becomes End-Of- Stream iterator */ } else { ++m_current_count; Base::operator++(); } return *this; } }; #include <algorithm> /* copy */ #include <string> /* string */ #include <sstream> /* istringstream */ #include <iostream> /* cout, endl */ #include <iterator> /* back_inserter */ auto main(void) -> int { std::istringstream iss("123456789"); std::string str; /* Let's use copy to read 5 char's into our string */ std::copy( istream_iterator_limited<char>(iss,5), istream_iterator_limited<char>(), std::back_inserter(str) ); std::cout << str << std::endl; str.clear(); /* Get another 3 */ std::copy( istream_iterator_limited<char>(iss,3), istream_iterator_limited<char>(), std::back_inserter(str) ); std::cout << str << std::endl; }

1 1

[release] Boost 1.72.0 Beta 1
by Michael Caisse 21 Nov '19

21 Nov '19

Boost release 1.72.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.72.0.beta.1/source/> The SHA256 checksums are as follows: 5a6b5cbd27b8ca0c7741b715e022a3bf05aecbb1e73dc72dd82eef9622374bd5 boost_1_72_0_b1.7z 6c85a7aed198757f5e4be66a971ae90a25c4ce32703fecfb5bb19019bd80947c boost_1_72_0_b1.tar.bz2 be4a3fdaa84d5a8b25863651043308e02645f3fbf772b7623ee6462fb1dbad09 boost_1_72_0_b1.tar.gz 95181a5f3de0078b8fc031f63a4dc8be4d70b7d3d5cde3b266d2cd98bd4b61b0 boost_1_72_0_b1.zip For details of what's in the release, see <https://www.boost.org/users/history/version_1_72_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

1 0

[release] Boost 1.72.0 Beta 1 Release Candidate 2
by Marshall Clow 21 Nov '19

21 Nov '19

Boost release 1.72.0 beta 1 rc2 is now available at: <https://dl.bintray.com/boostorg/beta/1.72.0.beta.1.rc2/source/> The release notes are not yet available. The updated documentation is not yet available. [ They will be available in a day or two. ] The SHA256 checksums are as follows: 5a6b5cbd27b8ca0c7741b715e022a3bf05aecbb1e73dc72dd82eef9622374bd5 ./boost_1_72_0_b1_rc2.7z 6c85a7aed198757f5e4be66a971ae90a25c4ce32703fecfb5bb19019bd80947c ./boost_1_72_0_b1_rc2.tar.bz2 be4a3fdaa84d5a8b25863651043308e02645f3fbf772b7623ee6462fb1dbad09 ./boost_1_72_0_b1_rc2.tar.gz 95181a5f3de0078b8fc031f63a4dc8be4d70b7d3d5cde3b266d2cd98bd4b61b0 ./boost_1_72_0_b1_rc2.zip Changes since RC1: * Fix Boost.IOStreams to allow compilation on Mac OS w/LZMA support. Please download the beta release candidate, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

2 2

[release] Boost 1.72.0 Beta 1 Release Candidate 1
by Michael Caisse 18 Nov '19

18 Nov '19

Boost release 1.72.0 beta 1 rc1 is now available at: <https://dl.bintray.com/boostorg/beta/1.72.0.beta.1.rc1/source/> The release notes are not yet available. The updated documentation is not yet available. [ They will be available in a day or two. ] The SHA256 checksums are as follows: 3dd80fc3979c312bf892398c35778d821f6744a7fbf76c8248c85b4f3702e4d4 boost_1_72_0_b1_rc1.7z 676e476a2a1246c7c5e8f40230fa70469f29dfe8aaa5bce0a85f94692e605c68 boost_1_72_0_b1_rc1.tar.bz2 e62e5fdffe0772309c77fc9463a95350ebcabb2ce03f2c6ee177123016756044 boost_1_72_0_b1_rc1.tar.gz e3199f3f5046541570fffacd804d736e1999cfac05df6cc054ec97c8098d000d boost_1_72_0_b1_rc1.zip Please download the beta release candidate, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

4 8

回复：Re: [release] Boost 1.72.0 Beta 1 Release Candidate 1
by ckgppl_yan＠sina.cn 18 Nov '19

18 Nov '19

I can compile this release in my macOS catalina, 10.15.1. I don't have lama installed in my OS, so I didn't have the issue below.only some warnings out. Thanks Liang----- 原始邮件 ----- 发件人：Marshall Clow via Boost <boost(a)lists.boost.org> 收件人：turkanis(a)coderage.com, Michael Caisse <mcaisse-lists(a)ciere.com> 抄送人：Marshall Clow <mclow.lists(a)gmail.com>, "boost(a)lists.boost.org List" <boost(a)lists.boost.org> 主题：Re: [boost] [release] Boost 1.72.0 Beta 1 Release Candidate 1 日期：2019年11月19日 04点38分 This appears to be https://github.com/boostorg/iostreams/issues/102, and https://github.com/boostorg/iostreams/pull/103 is a suggested fix. -- Marshall On Mon, Nov 18, 2019 at 11:56 AM Marshall Clow <mclow.lists(a)gmail.com> wrote: > On my Mac, I the version of LZMA that I have installed (via homebrew) does > not have the multi-tasking calls (_lzma_cputhreads and > _lzma_stream_encoder_mt). > It identifies itself: > > $ cat junk.cpp > #include <iostream> > #include "lzma.h" > > int main() { > std::cout << LZMA_VERSION << std::endl; > } > > $ clang++ junk.cpp && ./a.out > 50020042 > $ > > Changing libs/iostreams/src/lzma.cpp thus solves enables things to build: > > #ifndef BOOST_IOSTREAMS_LZMA_NO_MULTITHREADED > - #if LZMA_VERSION < 50020002 > + #if LZMA_VERSION <= 50020042 > #define BOOST_IOSTREAMS_LZMA_NO_MULTITHREADED > #endif > #endif > > -- Marshall > _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

1 0

Required C++ version in meta/libraries.json
by Mateusz Loskot 18 Nov '19

18 Nov '19

Hi, How can I specify required version of the standard in the library meta info? Where is documentation of libraries.json schema? I've learned that "std":"C++17", for example, in Boost.Any states which standard adopted the library. That is not what I'm after. -- Mateusz Loskot, mateusz(a)loskot.net (Sent from mobile, may suffer from top-posting)

1 1

Jason is getting MARRIED!
by Vinnie Falco 18 Nov '19

18 Nov '19

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? Thanks!

3 4

pulling the plug on Boost Library Incubator
by Robert Ramey 17 Nov '19

17 Nov '19

I've been maintaining the Boost Library Incubator (www.blincubator.com) for some years now. Maintaining is sort of mis-nomer since it not required any change for years now. I never, ever touch it. I was painful to get to that point though. My motivation is the continuing evolution of github which I believe has come to embody almost of the goals I've had for the inclubator. I would like a couple of tweaks to git hub - or maybe just some changes in our usage of it. For example I'd like to see us proliferate the tags #Boost and #ProposedForBoost to help us search stuff but basically I believe that it has made boost library incubator obsolete. So I'm inclined to terminate it when the domain comes up for renewal the next time. Currently it has about 200 page views / day. I don't really know how much of that a bots/rss feeds and the like. I do you a service which detects and filters out almost all the obvious bogus hits, but still one never knows. BTW - the tipping point for me is the addition of "sponsership" to github. This looks to be the realization of an idea which I've promoted for many years in one for or another. I would like to successful open source project developers and maintainers get rewarded financially rewarded for their efforts and I see that git hub promoters seem to share this view - and they're in a position to move it toward reality. When I can't sleep at night, I imagine that microsoft looked at the incubator and copied features from it into the git hub. Feels like I'm dreaming so I don't feel like I'm awake anymore. Robert Ramey

1 0

Re: [boost] Jason is getting MARRIED!
by Peter Dimov 17 Nov '19

17 Nov '19

> or even `{ "size": 3, "data": [ 1, 2 ] }`. Er, "size": 2 obviously. :-)

1 0

Fwd: Markdown to Quickbook
by Mateusz Loskot 15 Nov '19

15 Nov '19

As boost-docs may not be as popular among subscribers as the development list, I'm bumping my chances for solution... ---------- Forwarded message --------- From: Mateusz Loskot <mateusz(a)loskot.net> Date: Mon, 11 Nov 2019 at 21:25 Subject: Markdown to Quickbook To: <boost-docs(a)lists.boost.org> Hi, Is there an established known method for converting a Markdown document to Quickbook dokument? Best regards, Mateusz Loskot, mateusz(a)loskot.net (Sent from mobile, may suffer from top-posting) -- Mateusz Loskot, http://mateusz.loskot.net

3 3

Removing old branches
by Edward Diener 15 Nov '19

15 Nov '19

I received an issue about Boost PP having lots of old branches which the issuer would like removed. I notice most other Boost libraries also have lots of old branches. Is there any policy about removing these old branches from a Boost library repository ? Many of these old branches are svn-branches, but most of them do not have any value any more and, of course, do not affect the current 'develop' or 'master' branch.

5 7

[preprocessor] Testing C++ standard macro examples
by Edward Diener 14 Nov '19

14 Nov '19

I have added to the 'develop' branch of Boost PP an 'explicit' test with the alias of 'test_iso' in the 'test' subdirectory. This test, depending on the compiler toolset and C++ standard setting used, will test a compiler's ability to expand correctly the macros listed in a C++ standard document's "Macro Replacement" section for C++ standards 2003, 2001, 2014, 2017, and 2020 ( N4835 ). The test uses the __cplusplus setting and the Boost PP BOOST_PP_VARIADICS setting to determine which C++ standard's set of macros to test. This is because the __cplusplus setting alone is misleading for a number of compilers, most notably vc++ and compilers who mimic vc++, who do not set the correct __cplusplus setting for the C++ standard level being used. There are really only three sets of macros from the C++ standard documents which can potentially be tested, despite five different standards being considered. This is because the set of macros to be tested for C++11, C++14, and C++17 are exactly the same. Some compilers do allow C++20 support but do not implement the full __VA_OPT__ support yet, so these compilers will fail the C++20 macro tests with compiler errors. Among these are gcc and vc++, who both document that they do not yet support the stringizing operator with the __VA_OPT__ parameter. Clang also supports C++20 and will run the test and succeed in that mode. You can of course test any compiler at any C++ level and view the results. These tests, unlike Boost PP, do not have any workarounds for any compilers. So the tests form a really good basis for reporting macro expansion preprocessor bugs to various compiler implementations. In the 'test' subdirectory of Boost PP you should be able to run: b2 toolset=atoolset cxxstd=astandard( optional ) test_iso to get the results for any compiler. Any failed results will show the test output, where the original expression, the expanded expression, and for individual failed tests the expected expanded expression will be shown. The actual macros being used are in the appropriate C++ Standard documents or can be seen in the test program which is called cpp_standard.cpp in the same 'test' subdirectory. After the upcoming release I will push this to the 'master' branch. Please note that the test is an 'explicit' test so it is not normally run when you just run the tests for Boost PP.

1 0

fixed_string: Request for review
by Krystian Stasiowski 13 Nov '19

13 Nov '19

Hi all, My name Is Krystian Stasiowski. I'm currently attending college as a Computer Science major, am active on the C++ Language Slack, and starting to contribute to ISO C++. Vinnie offered for me to take the lead on submitting Boost.FixedString for a formal review, so here I am! Applicable links: Github: https://github.com/18 Repo: https://github.com/18/fixed_string Docs: https://18.github.io/doc/fixed_string

2 1

Late fix for Boost PP
by Edward Diener 12 Nov '19

12 Nov '19

I had added support in the Boost PP library in C20 mode ( __cplusplus > 201703L ) for the __VA_OPT__ construct and enhanced an internal function used fairly extensively in the library to use this functionality in c20 mode when __VA_OPT__ was supported. I had tested this against the compilers which I knew could operate in c20 mode, gcc and clang, and all was well. I just discovered that the vc++ compiler can also work in c20 mode in Boost PP as defined above if you pass the '/std:c++latest' and the '/Zc:__cplusplus' command line switches and that vc++, in its usual non-standard way, blows up badly when doing so using the preprocessor library because it can not handle the rather simple code that checks for __VA_OPT__ support in c20 mode. I have a simple fix for this which is to turn off the __VA_OPT__ support and __VA_OPT__ support checking in c20 mode specifically for vc++ and removes which I have pushed to 'develop'. Can I push this fix to the 'master' branch now ? The fix needs to get in the coming release or else vc++ programmers specifying both the '/std:c++latest' and the '/Zc:__cplusplus' command line switched will not be able to use Boost PP and the many libraries which use Boost PP in the upcoming release. I apologize for the seeming aggressiveness of this change, which incorporated the c20 __VA_OPT__ support internally in some much-used Boost PP functionality when c20 mode is being used, but I did not anticipate that it would blow up on me, although maybe I should have. I can also remove that internal dependency with a very simple one-line change. I realize that Boost PP stability has to be maintained, even in c20 mode for the few compilers which support that mode and apologize again that I have endangered it there.

1 1

Re: [boost] [Boost][Proposal] library for enhanced switch syntax.
by рустам абдумаликов 12 Nov '19

12 Nov '19

Phil Endecott wrote: > Specifically thinking about strings, there are numerous ways > that it could be done. Starting with > (1): the obvious sequence of if-else-if: > ... > (2): binary search using nested switches: > ... > (3) character-by-character comparison using nested switches: > ... > (4) converting to a 64-bit integer, for strings of up to 8 characters: > ... Firstly my implementation was never particularly about string in "switch" it is just one of the applications. Secondly, example 3-4 assume additional implementation( can take quite a time to do it right ), it isn't like you have it out of the box, this is exactly what my statement was about( example 1-2 don't count, they are non-scalable ). Lets rather consider something that is more complex: -- Example_1 "Parse file by extension": switch( hash_it( get_file_extention( file_name ) ) ) { case "cpp"HASH: case "cc"HASH: case "c++"HASH: case "cxx"HASH: case "C"HASH: { ... } break; case "hpp"HASH: case "hh"HASH: case "h++"HASH: case "hxx"HASH: case "H"HASH: { ... } break; } // OR // I think this way it is much readable eswitch( get_file_extention( file_name ) ) >> case_( any_from( "cpp", "cc", "c++", "cxx", "C" ) ) >> [&]{...} >> case_( any_from( "h", "hpp", "hh", "h++", "hxx", "H" ) ) >> [&]{...}; // OR // even this could be possible( but not yet implemented ) eswitch( get_file_extention( file_name ) ) >> case_( "cpp", "cc", "c++", "cxx", "C" ) >> [&]{...} >> case_( "h", "hpp", "hh", "h++", "hxx", "H" ) >> [&]{...}; -- Example_2 "Parse HTTP header with Regex": // O_o too much boilerplate if( std::regex_match( line, "^.+ 200 .+$"_r ) ){...} else if( std::regex_match( line, "^.+ 404 .+$"_r ) ){...} else if( std::regex_match( line, "^.+: .+$"_r ) ){...} else { terminate(); } // OR // I think this way your intention is clearer eswitch( line ) >> case_( "^.+ 200 .+$"_r ) >> []{...} // match for "HTTP/1.1 200 OK" case_( "^.+ 404 .+$"_r ) >> []{...} // match for "HTTP/1.1 404 Not Found" case_( "^.+: .+$"_r ) >> [&]{...} >> // match for "key: value" default_ >> []{ terminate(); }; -- Example_2 "match in range of values": // Error prone approach if( value >= 1 && value <= 10 ){ Print("Value in a range[1,10]"); } if( value >= 11 && value <= 20 ){ Print("Value in a range[11,20]"); } else { Print('?'); }; /// OR eswitch( value ) >> case_( _1.in( 1, 10 ) ) >> []{ Print("Value in a range[1,10]"); } >> case_( _1.in( 11, 20 ) ) >> []{ Print("Value in a range[11,20]"); } >> default_ >> []{ Print('?'); }; // _1 it is lazy index mapping for the params in eswitch I my opinion "eswitch" looks more readable, more intuitive, less error prone and furthermore it is extensible. P.S. Here https://github.com/rabdumalikov/proposals/blob/master/eswitch_boost_proposa… I had described why I think it is important( just in case you've missed it ).

3 4

[release] 1.72.0 closed for Beta
by Michael Caisse 11 Nov '19

11 Nov '19

The master branch is now closed for all changes except by permission for the Beta release. Also, remember to add your libraries' changes to the release notes at: <https://github.com/boostorg/website/blob/master/feed/history/boost_1_72_1.q…> Thanks, -- The Boost Release Team

4 4

[Boost][Proposal] library for enhanced switch syntax. Request for Comments
by рустам абдумаликов 11 Nov '19

11 Nov '19

Hi All, I wrote a library *eswitch* which provides enhanced functionality for* C++ switch*. Please take a look and leave your comments. *=====================* *Motivation:* *=====================* To overcome "*native switch*" limitations: - one parameter per "*native switch*" - the parameter restricted to only *integral *types( int, char, enum ... ). "*eswitch*" supports any number of parameters and almost without restriction on their *type*, as long as the *type *is comparable( i.e. has* operator==* ). *=====================Why it is important?=====================* Here is the most viewed questions on the *stackoverflow*: FEATURE VIEWS Multiple conditions in switch case <https://stackoverflow.com/questions/68578/multiple-cases-in-switch-statement> 850k Switch for string <https://stackoverflow.com/questions/650162/why-the-switch-statement-cannot-…> 693k Case match in range <https://stackoverflow.com/questions/9432226/how-do-i-select-a-range-of-valu…> 133k Over a million views indicate how many people out there are disappointed with limited functionality of "*native switch*". Building parallels with such operators as "*if*"/"*while*"... it is expected by default that "*native switch*" should have the same possibilities: - be able to work with *non-integral* types as well - be able to compose complex conditions like we do in other operators " *if*"/"*while*"... Unfortunately it is not the case up till now. There was a proposal in 2013 *Relax switch statement <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3627.html>*, and committee agreed about importance of this topic. There also was *StringSwitch <http://llvm.org/doxygen/classllvm_1_1StringSwitch.html>* implementation by *LLVM *and *Case ranges <https://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html>* non-standard extension which is supported by *gcc*, *intel C/C++* and *clang*. Nevertheless, we still don't have common and universal solution. People want to overcome current "*native switch*" limitation either by implementing their own solution, non-standard extension or even trying to standardize it. Making proposed *eswitch <https://github.com/rabdumalikov/eswitch_v4>* functionality part of the *Boost-Library *will provide millions of developers useful, universal and agile functionality in order to finally fulfill their needs. *=====================repository:=====================* https://github.com/rabdumalikov/eswitch_v4 *=====================References:=====================/// "switch for non-integral" on stackoverflow* 1. https://stackoverflow.com/questions/650162/why-the-switch-statement-cannot-… 2. https://stackoverflow.com/questions/16388510/evaluate-a-string-with-a-switc… 3. https://stackoverflow.com/questions/5452188/switch-case-statement-in-c-with… 4. https://stackoverflow.com/questions/19273092/character-in-switch-statement-c 5. https://stackoverflow.com/questions/4165131/c-c-switch-for-non-integers 6. https://stackoverflow.com/questions/27536575/switch-case-on-char */// "Multiple conditions" on stackoverflow* 7. https://stackoverflow.com/questions/8644096/multiple-conditions-in-switch-c… 8. https://stackoverflow.com/questions/68578/multiple-cases-in-switch-statement */// "Ranges in case" on stackoverflow* 9. https://stackoverflow.com/questions/9432226/how-do-i-select-a-range-of-valu… */// "Case ranges" - non-standard extension* 10. https://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html */// LLVM "StringSwitch"* 11. http://llvm.org/doxygen/classllvm_1_1StringSwitch.html */// "Relax switch statement" proposal* 12. http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3627.html */// "N3627 Relaxed switch statement" c++ committee status* 13. https://cplusplus.github.io/EWG/ewg-active.html *Best Regards.*

7 7

[Boost][Proposal] library for enhanced switch syntax. Request for Comments #2
by рустам абдумаликов 09 Nov '19

09 Nov '19

Hi All, First attempt kind of failed due to alignment:( So this is another one) So I wrote a library eswitch which provides enhanced functionality for C++ switch. Please take a look and leave your comments. Motivation: To overcome native switch limitations: 1) one parameter per switch 2) the parameter restricted to only integral types( int, char, enum ... ) Whereas "eswitch" supports any number of parameters and almost without restriction on their type, as long as the type is comparable( i.e. has operator== ). Why it is important? Because people want to overcome current switch limitation either by implementing their own solution, non-standard extension or even trying to standardize it. Making proposed eswitch functionality part of the Boost-Library will provide millions of developers useful, universal and agile functionality in order to finally fulfill their needs. Full proposal here: https://github.com/rabdumalikov/proposals/blob/master/eswitch_boost_proposa… Repository: https://github.com/rabdumalikov/eswitch_v4 Best Regards Rustam Abdumalikov

2 1

Re: [boost] fixed_string: Request for review
by Ggh 09 Nov '19

09 Nov '19

First: 1)wonderful documentation! 2) A few ideas => 2.1)find_count_of =>find number of occurences of 'argument' 2.2)get_sequence_of =>return sequence of 'begin'=>'end' 2.3)set_sequence_of => set sequence of 'begin'=>'end' with 'arg' 2.4)set_slice_of => ~= 2.3) 2.5)get_slice_of => ~= 2.2) 6)char_traits<T> here but =>> also for any type/class? Quoting Krystian Stasiowski via Boost <boost(a)lists.boost.org>: Good work! Please regard this as constructive critism, Ty G > Hi a > ,y > My name Is Krystian Stasiowski. I'm currently attending college as a > Computer Science major, am active on the C++ Language Slack, and starting > to contribute to ISO C++. Vinnie offered for me to take the lead on > submitting Boost.FixedString for a formal review, so here I am! > > Applicable links: > Github: https://github.com/18 > Repo: https://github.com/18/fixed_string > Docs: https://18.github.io/doc/fixed_string > > _______________________________________________ > Unsubscribe & other changes: > http://lists.boost.org/mailman/listinfo.cgi/boost Tell me, and I forget. Ask me, and I discover...

1 0

[container] static_string ?
by Vinnie Falco 09 Nov '19

09 Nov '19

Beast has static_string which someone has asked to be move, is there any interest in moving this to Boost.Container? See: <https://github.com/boostorg/beast/issues/1691> <https://github.com/boostorg/beast/blob/b7230f12f16fe7a9f7a1ece5be1f607c8552…> -- Regards, Vinnie Follow me on GitHub: https://github.com/vinniefalco

19 50

[Metrics] - library idea reviews
by cpijcke.wall＠laposte.net 08 Nov '19

08 Nov '19

Hi, Two years ago, I have created a library who handle metrics type (distance, speed, flow rate, ...). I have simply applied the principle of chrono library (std:: one from clang in my case) and have applied it to other types. I have decided some weeks ago to make it public on github. This project also manage inter-type conversion(speed to distance, or volume to flow rate for example). Before going much further in this project, I would like to get your though about it. Maybe some of you already have had a similar idea, maybe even in a more advanced state, or with another principle of conversion between types? Here is the project link: https://github.com/xtofpic/metrics if you are interested. In this case, don't blame me for the state of the code actually, I know it still need a huge works to do on testing and code reducing by better c++ templates. But if you can just let me know what you think of the idea? And if there is an opportunity to eventually integrate this project into boost afterwards? Best regards, Christophe Pijcke.

2 2

How to make boost write_xml not escape angle brackets?
by Ananya Maiti 07 Nov '19

07 Nov '19

Hi all, I am trying to write some data in a xml file using boost write_xml() function. My data has some angle brackets in it e.g. <![CDATA[name]]> . But when I use boost::property_tree::write_xml() to write the data node to xml file it escapes the angle brackets to < and > tags. I even tried using unicode \x3C , \x3E but still it escapes them. Is there any way to tell boost to not escape the characters in a non html safe way ? Regards, Ananyo Maiti

1 0

[1.72][Test][Math][Fiber] Recent breaking change in Boost.Test breaks fiber/math tests
by John Maddock 07 Nov '19

07 Nov '19

This change: https://github.com/boostorg/test/commit/1c4533f7654d4c049cc6a34a43a5c10cde5… To Boost test (which I'm sure has been long signaled, I just wasn't aware of it), breaks one Math lib test (develop and master), and quite a number of Fibre tests (also develop and master), the Math failure should be fixed in develop (https://github.com/boostorg/math/commit/1d04bf714e809d386088ce135e3f9ea04ca…) and will get merged to master once CI is green. Not sure if anything is in the works for Fiber. Just a wee heads-up. Best, John. -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

4 8

Best Boost to use for boost::python with Python 3.7/3.8?
by Kacvinsky, Tom 06 Nov '19

06 Nov '19

Subject is the question. Any recommendations? Looking at the boost documentation for boost::python, it doesn't look like the copyright has changed since 2015, but compiling boost 1.6.9.0, for instance, points out there have been code changes.

1 0

[Test] log_level (was RE: [1.72][Test][Math][Fiber] Recent breaking change in Boost.Test breaks fiber/math tests)
by Peter Bartlett 05 Nov '19

05 Nov '19

>I think it is very counter-intuitive that messages only emerge to the normal output if there is an error or --log_level="message" > >And that > > #define BOOST_TEST_LOG_LEVEL "message" > >does not appear to have the same effect as --log_level="message" > >which is also surprising, and in my book a buglet? > >I suggest that this behaviour should be changed so that BOOST_TEST_MESSAGE >*always* produces output. > >BOOST_AUTO_TEST_CASE(test_message) >{ > BOOST_TEST_MESSAGE("\nTest BOOST_TEST_MESSAGE.\n"); } // BOOST_AUTO_TEST_CASE(test_message) > >Otherwise I am sure I will not be the only person confused. > >At the very least the documentation should highlight that ones expectation may not match what actually happens. Hi, I think it would be a bad idea to change the default value of --log_level (in your suggestion, from "error" to "message"). The default has been "error" for a long time (I don't like to count how long, because it makes me feel old!). And I'm sure that a lot of parsing tools have been built around the world assuming Boost.Test output is of a certain form. I know I've had to 'teach' various CI systems Boost.Test-speak over the years. > #define BOOST_TEST_LOG_LEVEL "message" BOOST_TEST_LOG_LEVEL is supported as an environment variable, not as a macro. Supporting it as a macro would be a bad idea for similar reasons as above - the layout and volume of the output should be for the *user* to control not the author of the tests, or otherwise the user can't rely on what the test output is going to look like from one library to the next. If you, personally, always want the log_level to be 'message', then you should set the environment variable BOOST_TEST_LOG_LEVEL permanently on your system. Hope that helps, Pete

1 0