220 3595 <85c0ae97-3440-4a81-96c2-1af7ebb892ba@isocpp.org> article Path: news.gmane.org!not-for-mail From: Andrew Sandoval Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: "break break ;" etc. to break out of nested loops Date: Fri, 5 Apr 2013 12:53:33 -0700 (PDT) Lines: 114 Approved: news@gmane.org Message-ID: <85c0ae97-3440-4a81-96c2-1af7ebb892ba@isocpp.org> References: <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_526_31641456.1365191613317" X-Trace: ger.gmane.org 1365273224 25858 80.91.229.3 (6 Apr 2013 18:33:44 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 6 Apr 2013 18:33:44 +0000 (UTC) Cc: temptony@freemail.hu To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDIZ5RW5Y4IBBQGX7SFAKGQEKU3RE7A@isocpp.org Sat Apr 06 20:33:46 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ob0-f199.google.com ([209.85.214.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UOXKy-0004DB-F7 for gclcip-std-proposals@m.gmane.org; Sat, 06 Apr 2013 19:55:36 +0200 Original-Received: by mail-ob0-f199.google.com with SMTP id va7sf308057obc.2 for ; Sat, 06 Apr 2013 10:55:35 -0700 (PDT) X-Received: by 10.182.237.12 with SMTP id uy12mr3427769obc.20.1365191616304; Fri, 05 Apr 2013 12:53:36 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.132.110 with SMTP id ot14ls468082obb.18.gmail; Fri, 05 Apr 2013 12:53:34 -0700 (PDT) X-Received: by 10.182.16.35 with SMTP id c3mr283009obd.31.1365191614805; Fri, 05 Apr 2013 12:53:34 -0700 (PDT) In-Reply-To: <1f964e4b-2762-43b8-85e5-41392926b07a@isocpp.org> X-Original-Sender: sandoval@netwaysglobal.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:3595 Archived-At: ------=_Part_526_31641456.1365191613317 Content-Type: text/plain; charset=ISO-8859-1 On Friday, April 5, 2013 2:23:33 PM UTC-5, temp...@freemail.hu wrote: > > 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? > How about *return*? That way you are pushed towards keeping your functions simple. Not trying to be negative, but that seems like something you wouldn't hit too often in C++ code -- C, yes, but hopefully not C++. -Andrew Sandoval -- --- 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_526_31641456.1365191613317 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On Friday, April 5, 2013 2:23:33 PM UTC-5, temp...@freemail.hu wrote:I hesitate to suggest this simple en= hancement to the language, because it's so obvious that somebody mus= t have thought of it before. In which case there must have been a good reas= on for rejecting it! But here goes:

Problem<= /div>
The break statement jumps out of the nearest enclosin= g do, for, switch, or while statement. All programmers know t= hat breaking out of a nested for-loop to the second-nearest enclosin= g do, for, switch, or while statement is = a pain, and requires a goto statement or worse.

<= /div>
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&nb= sp;break statement jumps out of the third-nearest enclosin= g do, for, switch, or while statement.
The break break break break s= tatement jumps out of the fourth-nearest enclosing do, for, switch,=  or while statement.

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++) {
  &n= bsp;   // do stuff
      if (a[i][j][k] =3D= =3D 0) break break break ; // the same as "goto ContinueExecution ;"
<= div>    }
ContinueExecution:

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

How about return?  That way you are pushed towards keeping yo= ur functions simple.
Not trying to be negative, but that seems like some= thing you wouldn't hit too often in C++ code -- C, yes, but hopefully not C= ++.

-Andrew Sandoval
 

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