220 33742 article Path: news.gmane.org!.POSTED!not-for-mail From: Tony V E Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: A more advanced switch Date: Wed, 9 Aug 2017 16:17:07 -0400 Lines: 118 Approved: news@gmane.org Message-ID: References: <574320af-c1ae-4676-883c-ae4e91fcd874@isocpp.org> <41733595.o4GQ0c89LU@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="001a1140c548a28efe055657c3b9" X-Trace: blaine.gmane.org 1502309834 29824 195.159.176.226 (9 Aug 2017 20:17:14 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 9 Aug 2017 20:17:14 +0000 (UTC) To: Standard Proposals Original-X-From: std-proposals+bncBCUZ5QWKNQIMJW5NZQCRUBHOWEQGG@isocpp.org Wed Aug 09 22:17:08 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f197.google.com ([209.85.220.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dfXPb-0007B5-JS for gclcip-std-proposals@m.gmane.org; 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[2607:f8b0:400d:c0d::231]) by mx.google.com with ESMTPS id 2si3788650qtp.523.2017.08.09.13.17.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 Aug 2017 13:17:08 -0700 (PDT) Received-SPF: pass (google.com: domain of tvaneerd@gmail.com designates 2607:f8b0:400d:c0d::231 as permitted sender) client-ip=2607:f8b0:400d:c0d::231; Original-Received: by mail-qt0-x231.google.com with SMTP id v29so43083569qtv.3 for ; Wed, 09 Aug 2017 13:17:08 -0700 (PDT) X-Received: by 10.237.60.247 with SMTP id e52mr12509716qtf.106.1502309827906; Wed, 09 Aug 2017 13:17:07 -0700 (PDT) Original-Received: by 10.237.42.10 with HTTP; Wed, 9 Aug 2017 13:17:07 -0700 (PDT) In-Reply-To: <41733595.o4GQ0c89LU@tjmaciei-mobl1> X-Original-Sender: tvaneerd@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=FpH5DLxT; spf=pass (google.com: domain of tvaneerd@gmail.com designates 2607:f8b0:400d:c0d::231 as permitted sender) smtp.mailfrom=tvaneerd@gmail.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=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:33742 Archived-At: --001a1140c548a28efe055657c3b9 Content-Type: text/plain; charset="UTF-8" On Wed, Aug 9, 2017 at 3:38 PM, Thiago Macieira wrote: > On quarta-feira, 9 de agosto de 2017 10:08:14 PDT Tony V E wrote: > > So you have a pointer s, which is just an int, right? > > And all the cases are compile/link time constants... > > I'm not sure that was valid C, but it worked. Many years ago. > > > > Tony > > Something like this? > > switch ("A") { > case "A": > return 0; > case "B": > return 1; > default: > return 2; > } > > It doesn't compile in C: https://godbolt.org/g/m9Asnk (Clang) & > https://godbolt.org/g/Uy1pKW (GCC) > > Even if it did, what do you think this would return? I'd say it's equally > correct to return 0 or 2. > > yep, basically. Once upon a time some compiler compiled that, and I agree, I wouldn't guarantee what it returned. (I think the idea was that hitting the "A" case was an optimization, and case default was to do a strcmp()) This was more than 20 years ago. Oh my. Maybe 30 years ago. But that doesn't mean "more than 20" is incorrect, so I'll just keep telling myself "20", I've coded for 20+ years. Tony -- 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/CAOHCbiv6n3oFG9Xj%2BQgPRhwdN2xDUV0zZvtYXXiALOXE3vOUhA%40mail.gmail.com. --001a1140c548a28efe055657c3b9 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Wed, Aug 9, 2017 at 3:38 PM, Thiago Macieira <<= a href=3D"mailto:thiago@macieira.org" target=3D"_blank">thiago@macieira.org= > wrote:
O= n quarta-feira, 9 de agosto de 2017 10:08:14 PDT Tony V E wrote:
> So you have a pointer s, which is just an int, right?
> And all the cases are compile/link time constants...
> I'm not sure that was valid C, but it worked.=C2=A0 Many years ago= ..
>
> Tony

Something like this?

=C2=A0 =C2=A0 =C2=A0 =C2=A0 switch ("A") {
=C2=A0 =C2=A0 =C2=A0 =C2=A0 case "A":
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return 0;
=C2=A0 =C2=A0 =C2=A0 =C2=A0 case "B":
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return 1;
=C2=A0 =C2=A0 =C2=A0 =C2=A0 default:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return 2;
=C2=A0 =C2=A0 =C2=A0 =C2=A0 }

It doesn't compile in C: https://godbolt.org/g/m9Asnk (Clang) = &
https://godbolt.org/g/Uy1pKW (GCC)

Even if it did, what do you think this would return? I'd say it's e= qually
correct to return 0 or 2.



yep, basic= ally.

Once upon a time some compiler compiled that, and I= agree, I wouldn't guarantee what it returned.
(I think t= he idea was that hitting the "A" case was an optimization, and ca= se default was to do a strcmp())

This was more than 20 ye= ars ago.
Oh my. Maybe 30 years ago.
But that doesn= 't mean "more than 20" is incorrect, so I'll just keep te= lling myself "20", I've coded for 20+ years.

Tony
<= /div>

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