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From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: Weird response of "next" inside sub?
Message-ID: <11706@jpl-devvax.JPL.NASA.GOV>
Date: 6 Mar 91 23:47:20 GMT
References: <1991Mar6.172554.14299@iwarp.intel.com> <124820@uunet.UU.NET>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 29

In article <124820@uunet.UU.NET> rbj@uunet.UU.NET (Root Boy Jim) writes:
: In article <1991Mar6.172554.14299@iwarp.intel.com> merlyn@iwarp.intel.com (Randal L. Schwartz) writes:
: >Watch this:
: >
: >Yow!  The next exits the sub and cycles the outer "for" loop!  (This
: >bit me in a program today.)
: 
: I say leave it in. This is like catch/throw or setjmp/longjmp.
: As long as the subroutines are cleaned up ok, I'm all for it.

I think the subroutine is cleaned up okay, but it's still rather presumptous
of the subroutine to decide it was called from within a loop.  And note that
"next" is more or less equivalent to a return if there is a return statement
in the subroutine, since return is implemented internally using a BLOCK.
You'd still be able to say "next FILE", or whatever.

Guess what this does:

	sub foo {
	    return unless @_;
	    print "I say, ";
	    while ($_ = shift) {
		redo _SUB_ if /^;$/;
		print $_," ";
	    }
	}
	&foo(now,is,';',the,time);

Larry