220 33764 article Path: news.gmane.org!.POSTED!not-for-mail From: gmisocpp@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: A more advanced switch Date: Wed, 9 Aug 2017 18:13:12 -0700 (PDT) Lines: 123 Approved: news@gmane.org Message-ID: References: <574320af-c1ae-4676-883c-ae4e91fcd874@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_365_1320432237.1502327592752" X-Trace: blaine.gmane.org 1502327598 16398 195.159.176.226 (10 Aug 2017 01:13:18 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 10 Aug 2017 01:13:18 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCM3TRNUXUDBBKPGV3GAKGQEPJ7E6BQ@isocpp.org Thu Aug 10 03:13:13 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pg0-f72.google.com ([74.125.83.72]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dfc28-0003mP-Ov for gclcip-std-proposals@m.gmane.org; Thu, 10 Aug 2017 03:13:08 +0200 Original-Received: by mail-pg0-f72.google.com with SMTP id t80sf82349829pgb.0 for ; Wed, 09 Aug 2017 18:13:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=Op7XgquKR2AyGwRZwNEI2AEbZfGbZddUPVShiZoszpA=; b=bggMUdxyH7r7UdvpBqmiIULrbHDJ6k+UwHR/RA2l07S+TQxUhLRF7k0fZJ2msqQBsQ mrBZy152HYRgvG9RSIy1a/eC3ppuJ/XsvZyjy776k5ZnvGOzFr2BxAeczH/LWn4sd/eT 9ngJWxArA+8fMxjME/aHA6K6U9bM+i7+7CLb058duM6rPPy3qmMddj90ueWLzd7gUUNT MfZOYVfVSBVJpC+RyZ8XVz/7IPU+XtEIOnAtXqNxLQ9eQ/gg2ipZxg8w1ommFHr1JM0k 3AranolDJD3e4h5l26RgVKxtRIMPhIrYraBriXDJAKxV42E8d9IZSIt/ms//IJ7AqQOB yBmA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=Op7XgquKR2AyGwRZwNEI2AEbZfGbZddUPVShiZoszpA=; b=EiyuCtO+p+5xSHWRSMHxNJKcHOPvPZa7+nT2OfM1ejPx3o5hdCbn3Jo8SN8DGcMBLN 9b6iFjeyHJZfz72383S/HflUrDdLuX+Wu6DCBAnCUdxBsaDubsvBrU3uk5ATUvxDlC5v wvThI5QIPyFdVdK3Cu7dfsPXbA0XL3SDuZCK9tWKSq6J6P3F3HynTHP3Ai4KQJLhQA/g /EhUAnlryZSMtrMCIko9oQ1+mOJTvA5IQQxnQKlB4SZvctpI0ISfB6MhXZvnFCiLi293 ue7vwvy4cdnLS8Pg/JG9FmypLkzHlsnwjl5v6hgT5Pa70bjRn65i1g3P9ZSSC/VfBCZT k09Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=Op7XgquKR2AyGwRZwNEI2AEbZfGbZddUPVShiZoszpA=; b=VFR7O5nya/TqmD6lrbB4OwE1vaDSk9XV0zvN3Ty9MvW0n0aL8xWOEZH5oy60syI8qR F4AfLpwJWEBac/JdqdzUBKrEZ9wAhXP4sBiu22ta2m1cPfStHYDFIw4c6/8nXaUxFmpT JF8MlY1sxKe5bShKIXBLdi3iDojhx2zESygrDVWZHl8EhT8XqHCaGIZpVxEhmWd3hf4q hp2vBQgEHFcys9e+7XRA/2VUCxqeOqTQRslMaQywZzkFHqCMTpV6BlD+mWbS3gvogYtf rbPjNuhGF8ISTXIpDI7vvPIhevHsJHo81GCb8SIcWn4BcBHIQkKvqtF+p0WKLrl8gsLQ wJ0g== X-Gm-Message-State: AHYfb5jLD6XuR8HoQZzagAhs+UCjgBTdEUOa1PMmLIGEKf8DxnThuJ6x 1BeOp4YE3YcGWe4Z X-Received: by 10.99.122.79 with SMTP id j15mr6633180pgn.55.1502327594497; Wed, 09 Aug 2017 18:13:14 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.69.222 with SMTP id c91ls10474843itd.0.canary-gmail; Wed, 09 Aug 2017 18:13:13 -0700 (PDT) X-Received: by 10.31.41.67 with SMTP id p64mr43103vkp.16.1502327593208; Wed, 09 Aug 2017 18:13:13 -0700 (PDT) In-Reply-To: X-Original-Sender: gmisocpp@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:33764 Archived-At: ------=_Part_365_1320432237.1502327592752 Content-Type: multipart/alternative; boundary="----=_Part_366_1083946621.1502327592752" ------=_Part_366_1083946621.1502327592752 Content-Type: text/plain; charset="UTF-8" On Thursday, August 10, 2017 at 5:08:18 AM UTC+12, Tony V E wrote: > > break by default is fine, how do I opt-out within switch break, or is it > all or nothing? > > switch break(x) > { > case 1: > case 2: > foo(); > case 3: > bar(); > case 4: > etc(); > } > > > How do I get fallthru on case 1 to 2? > I would not object to fallthrough being a keyword like so (but see later): switch break(x) { case 1: fallthrough; case 2: foo(); case 3: bar(); case 4: etc(); } But I might prefer - in the absence of some range of values syntax - to make an empty case automatically fallthrough; and if you don't want to fall through use an empty statement as shown below, because the need is common and it's much briefer. switch break(x) { case 1: ; // Don't fall through. case 2: foo(); case 3: bar(); case 4: etc(); } And if you want to fallthrough in the middle of some case, just use goto. Which I think is clearer. And if you are using fallthrough that often, just use switch not switch break. What do you think? -- 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/bffc4188-593d-426e-bf4c-01c6a2952087%40isocpp.org. ------=_Part_366_1083946621.1502327592752 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Thursday, August 10, 2017 at 5:08:18 AM UTC+12,= Tony V E wrote:
break by defa= ult is fine, how do I opt-out within switch break, or is it all or nothing?=

switch break(x)
{
case 1:
case 2:
=C2=A0=C2=A0=C2=A0 foo();
case 3:
=C2=A0=C2=A0=C2=A0 b= ar();
case 4:
=C2=A0=C2=A0=C2=A0 etc();
=C2=A0}

How do I get fallthru on case 1 to 2?

I would not object to f= allthrough being a keyword like so (but see later):

switch break(x)
{
case 1: fallthrough;
case 2:
=C2=A0=C2=A0= =C2=A0 foo();
case 3:
=C2=A0=C2=A0=C2=A0 bar();
case 4:
=C2=A0= =C2=A0=C2=A0 etc();
=C2=A0}

But I might pre= fer - in the absence of some range of values syntax -=C2=A0to make an=C2=A0= empty case automatically fallthrough;
and if you don't want t= o fall through use an empty statement as shown below, because the need is c= ommon and it's much briefer.

switch break(x){
case 1: ; // Don't fall through.
case 2:
=C2=A0=C2=A0=C2= =A0 foo();
case 3:
=C2=A0=C2=A0=C2=A0 bar();
case 4:
=C2=A0=C2= =A0=C2=A0 etc();
=C2=A0}
And if you want to fallthrou= gh in the middle of some case, just use goto. Which I think is clearer.
And if you are using fallthrough that often, just use switch not swi= tch break.

What do you think?
=

--
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/bffc4188-593d-426e-bf4c-01c6a2952087= %40isocpp.org.
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