220 33555 article Path: news.gmane.org!.POSTED!not-for-mail From: Cleiton Santoia Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: A more advanced switch Date: Wed, 2 Aug 2017 21:29:01 -0700 (PDT) Lines: 236 Approved: news@gmane.org Message-ID: References: <9d888362-46f2-4317-b4ea-4376159d8ef1@isocpp.org> <722a37ea-6d3c-952a-f75e-376259a427cb@otoy.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_6738_195466846.1501734541603" X-Trace: blaine.gmane.org 1501734549 12003 195.159.176.226 (3 Aug 2017 04:29:09 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 3 Aug 2017 04:29:09 +0000 (UTC) Cc: ross.smith@otoy.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCBMVWMTUUNBBDWNRLGAKGQEFW6PR3A@isocpp.org Thu Aug 03 06:28:58 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f200.google.com ([209.85.161.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dd7kn-0002XB-DQ for gclcip-std-proposals@m.gmane.org; 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Wed, 02 Aug 2017 21:29:03 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.31.129 with SMTP id f123ls797206iof.43.gmail; Wed, 02 Aug 2017 21:29:02 -0700 (PDT) X-Received: by 10.31.191.67 with SMTP id p64mr1788vkf.4.1501734542093; Wed, 02 Aug 2017 21:29:02 -0700 (PDT) In-Reply-To: <722a37ea-6d3c-952a-f75e-376259a427cb@otoy.com> X-Original-Sender: cleitonsantoia@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:33555 Archived-At: ------=_Part_6738_195466846.1501734541603 Content-Type: multipart/alternative; boundary="----=_Part_6739_928355533.1501734541603" ------=_Part_6739_928355533.1501734541603 Content-Type: text/plain; charset="UTF-8" > > There's only so much elaboration that could be added to the switch > statement before it stops offering any meaningful advantage in > convenience or readability over just manually writing the equivalent > sequence of if-elses. > My "pet switch" would allow many conditions at once,and could be used in "not jump table" cases, like any object: std::string x = "AF-56"; int k = 90; enum YesNo{ NO,YES } answer; switch ( answer, k, x.substr(0,2) ) { case NO, default : // enters here if answer is NO and not check any of the others break; case YES, 10r.80r, default : // enters here if answer is yes and if k is in range 10-90, forget the third parameter // using UDL 'r' suffix and dot operator we may create a range that can compares thru operator == to a scalar break; case YES, 81, "XY" : // no surprises here break; case YES, 82r.Inf, "XZ" : // the range now is from 82 to infinity break; case YES, 90, "AA"r."AX"r : // ranges can be of std::strings too ( or const char* ), why not ? // This is actually the case that will be reached by (YES, 90, "AF") break; case default: } I know, comma may create problems, one may replace ',' with ';' This was my 2 cents -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/a6db0e72-dc61-4914-9508-31e2bc2c7462%40isocpp.org. ------=_Part_6739_928355533.1501734541603 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
There's o= nly so much elaboration that could be added to the switch=20
statement before it stops offering any meaningful advantage in=20
convenience or readability over just manually writing the equivalent=20
sequence of if-elses.

My "pet = switch" =C2=A0would allow many conditions at once,and could be used in= "not jump table" cases, like any object:

std= ::string x =3D "AF-56";
int k =3D 90;
enum YesNo{ NO,YES = } answer;

switch ( answer, k, x.substr(0,2) ) {case NO,= default : // enters here if answer is NO and no= t check any of the others
=C2=A0 =C2=A0 break;
case Y= ES,= 10r.80r, default : // enters here if answ= er is yes and if k is in range 10-90, forget the third parameter
=C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0// using UDL 'r' suffix and dot operator we may create a range t= hat can compares thru operator =3D=3D to a scalar
=C2=A0 =C2=A0 break;
case YES, 81<= /span>, &quo= t;XY"= :<= span style=3D"color: #000;" class=3D"styled-by-prettify"> =C2=A0// no surprises here = =C2=A0 = =C2=A0 =C2=A0 break;=
case YES, 82r.Inf, = "XZ" := =C2=A0// = the range now is from 82 to infinity
=C2=A0 =C2=A0 break;
case YES,= 90, "AA"r."AX"r : // ran= ges can be of std::strings too ( or const char* ), why not ?

=C2=A0 =C2=A0 // This is actually the= case that will be reached by (YES, 90, "AF")

=C2=A0 =C2=A0 break;
case default:
}


I know, comma = may create problems, one may replace ',' with ';'

This was my 2 cents

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
To post to this group, send email to std-proposals@isocpp.org.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/a6db0e72-dc61-4914-9508-31e2bc2c7462= %40isocpp.org.
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