220 3584 <1f964e4b-2762-43b8-85e5-41392926b07a@isocpp.org> article Path: news.gmane.org!not-for-mail From: temptony@freemail.hu Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: "break break ;" etc. to break out of nested loops Date: Fri, 5 Apr 2013 12:23:33 -0700 (PDT) Lines: 95 Approved: news@gmane.org Message-ID: <1f964e4b-2762-43b8-85e5-41392926b07a@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_388_11946196.1365189813293" X-Trace: ger.gmane.org 1365268599 14867 80.91.229.3 (6 Apr 2013 17:16:39 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 6 Apr 2013 17:16:39 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCF55ZN354IBBPWJ7SFAKGQES6YKS7Q@isocpp.org Sat Apr 06 19:16:41 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qe0-f71.google.com ([209.85.128.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UOWIV-0006hM-2l for gclcip-std-proposals@m.gmane.org; Sat, 06 Apr 2013 18:48:59 +0200 Original-Received: by mail-qe0-f71.google.com with SMTP id b10sf3873538qen.10 for ; Sat, 06 Apr 2013 09:48:58 -0700 (PDT) X-Received: by 10.236.139.230 with SMTP id c66mr5377054yhj.55.1365189823258; Fri, 05 Apr 2013 12:23:43 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.87.196 with SMTP id ba4ls392322qeb.3.gmail; Fri, 05 Apr 2013 12:23:33 -0700 (PDT) X-Received: by 10.49.27.102 with SMTP id s6mr1121494qeg.1.1365189813845; Fri, 05 Apr 2013 12:23:33 -0700 (PDT) X-Original-Sender: temptony@freemail.hu 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:3584 Archived-At: ------=_Part_388_11946196.1365189813293 Content-Type: text/plain; charset=ISO-8859-1 I hesitate to suggest this simple enhancement to the language, because it's so obvious that *somebody* must have thought of it before. In which case there must have been a good reason for rejecting it! But here goes: *Problem* The *break* statement jumps out of the nearest enclosing *do, for, switch, *or *while *statement. All programmers know that breaking out of a nested for-loop to the *second*-nearest enclosing *do, for, switch, *or *while *statement is a pain, and requires a *goto* statement or worse. *Suggestion* I suggest the following syntax: The *break break* statement jumps out of the second-nearest enclosing *do, for, switch, *or *while *statement. The *break break* *break *statement jumps out of the third-nearest enclosing *do, for, switch, *or *while *statement. The *break break* *break break *statement jumps out of the fourth-nearest enclosing *do, for, switch, *or *while *statement. And so on. For instance: for (int i = 0 ; i < 10 ; i++) for (int j = 0 ; j < 10 ; j++) for (int k = 0 ; k < 10 ; k++) { // do stuff if (a[i][j][k] == 0) break break break ; // the same as "goto ContinueExecution ;" } ContinueExecution: Easy to understand. Easy to implement. 100% backwards compatible. What's not to like? -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/?hl=en. ------=_Part_388_11946196.1365189813293 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable I hesitate to suggest this simple enhancement to the language, because it's= so obvious that somebody must have thought of it before. In which c= ase there must have been a good reason for rejecting it! But here goes:

Problem
The break stateme= nt jumps out of the nearest enclosing do, for, switch, or while <= /b>statement. All programmers know that breaking out of a nested for-loop t= o the second-nearest enclosing do, for, switch, or&= nbsp;while statement is a pain, and requires a goto = ;statement or worse.

Suggestion
I= suggest the following syntax:

The break&n= bsp;break statement jumps out of the second-nearest enclosing d= o, for, switch, or while statement.
The break break break statement jumps ou= t of the third-nearest enclosing do, for, switch, or = while statement.
The break break=  break break statement jumps out of the fourth-nearest enc= losing do, for, switch, or while statemen= t.

And so on. For instance:

for (int i =3D 0 ; i < 10 ; i++)
  for (int j =3D = 0 ; j < 10 ; j++)
    for (int k =3D 0 ; k < 10 ;= k++) {
      // do stuff
  &nb= sp;   if (a[i][j][k] =3D=3D 0) break break break ; // the same as "got= o ContinueExecution ;"
    }
ContinueExecutio= n:

Easy to understand. Easy to implement. 100%= backwards compatible. What's not to like?

--
 
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Visit this group at http://groups.google.com/a/isocpp.org/group/std-pro= posals/?hl=3Den.
 
 
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