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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.

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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 ).

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[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

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[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.*

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[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

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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...

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[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

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[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.

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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

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[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

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