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[Spirit] real_policies<> and 1.0#NAN
by Pete Bartlett 08 Jun '16

08 Jun '16

Hi, Boost.Spirit is not sure of itself when it comes to parsing representations of infs and nans such as “1.0#NAN”. The docs [1] for the default real_policies<T> for parsing numbers say: “[…] with the additional detection of NaN and Inf as mandated by the C99 Standard and proposed for inclusion into the C++0x Standard: nan, nan(...), inf and infinity (the matching is case-insensitive). This corresponds to the following grammar:” The first sentence suggests that 1.0#NAN etc will not be parsed. But the grammar itself then says: <quote> nan = -lit("1.0#") >> no_case["nan"] >> -('(' >> *(char_ - ')') >> ')') ; inf = no_case[lit("inf") >> -lit("inity")] ; </quote> suggesting that "#1.0NAN" is intended to parsed, but "#1.0INF" is not! Then the in-code docs [2] however suggest that both "1.0#NAN" and "1.0#INF" are intended to be parsed: <quote> // The second call allows to recognize representation formats starting // with a 1.0 (such as 1.0#NAN or 1.0#INF etc.). </quote> However, the actual code fails to parse either of these these. This is because in [3] the presence of the "0" causes frac_digits to be non-zero and so the "traits::is_equal_to_one(..)" condition is never tested. In the case "1.#NAN" (without a zero) frac_digits is zero so the condition is tested and we enter the traits::parse_nan code, but now the text parsed to this sub-parser is "#NAN" and the parser does not cater for the initial "#". Could the maintainers state which behaviour is intended...hopefully I may be able to supply a patch to docs/code/tests knowing that. Regards, Pete [1] http://www.boost.org/doc/libs/1_61_0/libs/spirit/doc/html/spirit/qi/referen… [2] <boost/spirit/home/qi/numeric/real_policies.hpp> [3]<boost/spirit/home/qi/numeric/detail/real_impl.hpp>

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RFC : About forking a C++11 standard library and adapt it to C++98 compilers
by Vicente J. Botet Escriba 07 Jun '16

07 Jun '16

Hi, Some of us have to work yet with C++98 compiler at work (due to well know reasons) and this for a long time. This is a reality. I was wondering about forking a public domain C++11/14/17 standard library and adapt it to C++98 compilers. This library could be seen as another TR1, an extension of the C++03 standard library. Does this make any sens? Would this project be of interest for the Boost/C++ community? I have not a clear idea of the cost of doing this work, how it should be done, what would be the limitations, ... but I'm sure that this would be quite useful on the projects that are forced to use C++98 and an excellent bridge to those that will move from C++98 to C++11 compilers. There are some Boost libraries that could be used to reduce the limitations, as Boost.Config/Predef, Boost.Move, ...and others that could be used as inspiration on how to implement them using C++98. Anyway, if you find that this will be useful to you at your work we will need your participation. Would you be interested in working on it? as a Boost community project? outside Boost, as an independent project? Comments and suggestion welcome. Best, Vicente P.S. The same can be done for C++14 standard libraries and the future standard C++17 libraries P.S.S. The same can be done for C++14 libraries and the future C++17 libraries but this time adapting to C++11 compilers (this will be much easier but the concerned community will be quite different ).

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Make libs/maintainers.txt a template file
by Daniel James 07 Jun '16

07 Jun '16

Hi, If you haven't noticed, on develop libs/libraries.htm is now a template which gets filled in as part of the documentation build. You can see the template and generated files at: https://github.com/boostorg/boost/blob/develop/libs/libraries.htm http://www.boost.org/doc/libs/develop/libs/libraries.htm This will be merged to master pretty soon. The only obstacle is updating the website automatically from the latest build, which should be happening very soon. The file libs/maintainers.txt is also automatically updated, but that's done in the repo itself, so that you have the full copy in you normal checkout. But I'm finding that people don't realise this, and we've had a few pull requests to update it manually. So instead, I think it might be a good idea to convert it to a template as well. This means you won't have a local copy, but will still be able to see a reasonably up to date copy online at: http://www.boost.org/doc/libs/develop/libs/maintainers.txt Any objections? I'm think of using similar templates for some other files, such as the root index.html (for the version number and new libraries). thanks, Daniel

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Cxx dual library
by Edward Diener 06 Jun '16

06 Jun '16

I have finished all the main work on the Cxx dual library at https://github.com/eldiener/cxx_dual. The library is also in the Boost Library Incubator at http://rrsd.com/blincubator.com/bi_library/cxx_dual-2/?gform_post_id=1597. The Cxx dual library, or CXXD for short, is a C++ macro header-only library which chooses between using a Boost library or its C++ standard equivalent library for a number of different C++ implementations, while using the same code to program either choice. An 'implementation' is a Boost library which has a C++ standard library equivalent whose public interfaces are nearly the same in both cases. An 'implementation' is called a 'dual library' in this documentation, or 'CXXD-mod' for short. The library does this by defining object-like macros for including the appropriate header file and namespace or using either the Boost library version or the C++ standard library version of a particular dual library. CXXD currently supports twenty eight different dual libraries, where the Boost version and the C++ standard version is nearly interchangeable in some respects. CXXD also provides a macro-based solution for distinguishing between the Boost version and the C++ standard version of a dual library so that specific code for a particular dual library choice may be written in those cases where the public interfaces diverge. The library came out of my initial PR to add such a feature to Boost.Config, and then I decided to create a separate library and expand on the functionality. The gist of the library is to write a single set of code for a particular implementation and have it work whether or not that code targets a Boost implementation or its C++ standard equivalent. The default algorithm will choose the C++ standard implementation if it is available, otherwise it chooses the Boost implementation. The default can be overriden for any of the 28 different implementations which CXXD supports. With all the talk about supporting C++11 or C++14 in new code, the library offers a way of supporting C++11 or C++14 standard libraries if available whether one writes in C++03 dialect or uses the new language features of C++11 on up. The Cxx dual library itself, being macro based, should work with any C++ code at that code's language level. The library itself is NOT, repeat NOT, an attempt to enforce a C++ language level for anybody who wants to use it. I have a little more work I am doing on increasing the support for Boost Build in the library, but all the central implementation of the library is complete in my mind. Questions, comments, or bug reports are always welcome, either here in this mailing list, in the Boost Library Incubator, or as Github issues, by those who are interested in trying the library out or reading the documentation. I will be using CXXD in another library on which I am working but hopefully others will find a use for it in their own code.

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[exception] Broken in master?
by John Maddock 06 Jun '16

06 Jun '16

Anything that includes Boost.Exception is currently broken on master for all compilers, for example: http://www.boost.org/development/tests/master/developer/output/teeks99-09j-… http://www.boost.org/development/tests/master/developer/output/Flast-FreeBS… The cause is the use of a partial-template specialization in info.hpp with no previous definition of class set_info_rv. Thanks, John.

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Boost.Fiber mini-review May 23 - June 1: review report
by Nat Goodspeed 05 Jun '16

05 Jun '16

The Boost.Fiber mini-review is now closed. Results: Bjorn Reese: YES Niall Douglas (private): YES Agustín K-ballo Bergé: YES Niall Douglas reminds me that in a previous mini-review he already voted to accept the Fiber library. Unless he stated that he had changed his mind, it would be reasonable to carry forward that "yes" vote. However, he did reaffirm his previous stance. In that spirit, let me remind the community of another couple previous positive votes: Eugene Yakubovich Antony Polukhin Significantly, there were no remaining NO votes. I therefore conclude that the Boost community ACCEPTS the Fiber library into the Boost family of libraries. On behalf of the Boost community, I would like to congratulate Oliver Kowalke not only for his engineering work, but for considerable patience in working to improve the library and its documentation. Thank you, Oliver!

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Re: [boost] Checking interest in std::get for PODs
by Bjorn Reese 04 Jun '16

04 Jun '16

On 06/03/2016 08:27 AM, Antony Polukhin wrote: > There's a C++14 library that is able to do basic reflections for PODs > without any macro magic or markup: https://github.com/apolukhin/magic_get Could the "Enums will be returned as their underlying type" limitation be partially worked around by allowing users to register their own enums?

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Checking interest in std::get for PODs
by Antony Polukhin 04 Jun '16

04 Jun '16

Hi, There's a C++14 library that is able to do basic reflections for PODs without any macro magic or markup: https://github.com/apolukhin/magic_get Would it be interesting for Boost? Could it pass Boost review if it has a reinterpret_cast in it? -- Best regards, Antony Polukhin

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Re: [boost] Cxx dual library
by Thomas Heller 04 Jun '16

04 Jun '16

Am 02.06.2016 8:56 nachm. schrieb "Edward Diener" <eldiener(a)tropicsoft.com>: > > I have finished all the main work on the Cxx dual library at https://github.com/eldiener/cxx_dual. The library is also in the Boost Library Incubator at > http://rrsd.com/blincubator.com/bi_library/cxx_dual-2/?gform_post_id=1597. > > The Cxx dual library, or CXXD for short, is a C++ macro header-only library which chooses between using a Boost library or its C++ standard equivalent library for a number of different C++ implementations, while using the same code to program either choice. An 'implementation' is a Boost library which has a C++ standard library equivalent whose public interfaces are nearly the same in both cases. An 'implementation' is called a 'dual library' in this documentation, or 'CXXD-mod' for short. > > The library does this by defining object-like macros for including the appropriate header file and namespace or using either the Boost library version or the C++ standard library version of a particular dual library. CXXD currently supports twenty eight different dual libraries, where the Boost version and the C++ standard version is nearly interchangeable in some respects. CXXD also provides a macro-based solution for distinguishing between the Boost version and the C++ standard version of a dual library so that specific code for a particular dual library choice may be written in those cases where the public interfaces diverge. Personally, I'm not a big fan of such a solution, especially when those macros "leak" into the public interface. We had a similar interface which would automatically switch between std and boost function. The result looked nice at first sight, however the subtle differences between the two led to various problems, one of which was that documenting the public interfaces containing this macro was very difficult, where does it point to know? Where should we send users to who look for more information about this function type? Should they be aware of both? Switching compilers or even boost version and now suddenly everything seems broken? The solution for us was to just decide which one to use and go with it, setting the requirements to the used standard library/boost version as needed.

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A retrospect on 'CMakeLists.txt' policy review
by David Sankel 04 Jun '16

04 Jun '16

Hello all, I wanted to thank everyone who participated in the CMakeLists.txt and related threads. I'm sorry I wasn't able to participate all the way through, but I found the majority of the posts to be civil and constructive (some of my own heated posts being notable exceptions). Here is my take away. No one is arguing that the current guidelines disallow authors from placing a CMakeLists.txt in the root of their library's directory. Some pointed out drawbacks of placing them there and recommended 'build/' or 'CMake/' instead. Others saw value in having CMakeLists.txt in the root directory, but felt these should be short wrappers where the real work is done in the 'build/' directory. Louis and Paul, I know you felt it important for your gitHub distribution to have 'CMakeLists.txt' in the root directory as is typical for CMake projects. Does this result satisfy your concerns? -- David Sankel

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