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From: merlyn@iWarp.intel.com (Randal L. Schwartz)
Newsgroups: comp.lang.perl
Subject: Re: next label not reported as a bad label in BLOCK
Message-ID: <1991Jun13.184509.20813@iWarp.intel.com>
Date: 13 Jun 91 18:45:09 GMT
References: <1991Jun13.092118.308@tcom.stc.co.uk>
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Reply-To: merlyn@iWarp.intel.com (Randal L. Schwartz)
Organization: Stonehenge; netaccess via Intel, Beaverton, Oregon, USA
Lines: 54
In-Reply-To: graham@tcom.stc.co.uk (Graham Bardsley)
Nntp-Posting-Host: se.iwarp.intel.com

In article <1991Jun13.092118.308@tcom.stc.co.uk>, graham@tcom (Graham Bardsley) writes:
| 
|   Perl doesn't complain that having a 'next' statement inside a plain block is
| an invalid use of next. This has I think been a long-standing `feature' since
| after finding a use of it in an old perl program of mine a bug has disappeared.
| Since perl complains about bad label usage everywhere else shouldn't it also
| complain about using next in this way? An example session is given below...
| 
| Cheers.
| 
| newt$ cat bug.pl
| #! /usr/local/bin/perl
| 
| $i=0;
| lab: {
| 	print "\$i=$i\n";
| 	$i++;
| 	next lab if ($i < 10);
| }

Gack.  Looks like perfectly reasonable code to me.  I often find
myself doing things like:

MAIN: {
	...
	...
	redo MAIN if $some_condition; # (jump to top)
	...
	...
	last MAIN if $some_condition; # (exit)
	...
	...
	next MAIN if $some_condition; # (go to next one, in this case exit)
	...
	...
	redo; # do it again
}

as a way of writing C's more obscure:

while (1) {
	...
	...
	...
}

Not a bug.  A feature.  And a nice one at that.

MAIN: { redo MAIN unless print "Just another Perl hacker,"; }
-- 
/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
| on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III      |
| merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn |
\=Cute Quote: "Intel: putting the 'backward' in 'backward compatible'..."====/