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From: lgy@phys.washington.edu (Laurence G. Yaffe)
Newsgroups: comp.lang.perl
Subject: Signal handlers, scoping & control confusion
Message-ID: <lgy.668295480@newton>
Date: 6 Mar 91 21:38:00 GMT
Sender: news@milton.u.washington.edu
Lines: 40

After reading 'the Book' & scanning the man page, I'm still confused about
signal handlers & scoping rules for things like statement labels &
subroutine names.  As an example, consider a structure like:

    {
    loop:
    foreach $file (...)
	{
	$SIG {'INT'} = 'interrupt' ;
	&compare (...) ;

	sub interrupt
	    {
	    last loop if (...) ;
	    }
	}
    return;
    }
    sub compare
	{
	if (...) { &interrupt ;}
	}

(a) The 'last loop' statement inside the handler 'interrupt' does seem
    to work.  If I omit the statement label on the 'last' statement inside
    the handler, then perl occasionally dumps core (this is at PL37).
    Should a label-less 'last', 'redo', etc. statement inside a
    nested subroutine work?  Even if the subroutine is a signal
    handler?  What determines if a statement label is in scope -
    lexical (static) scoping or dynamic scoping?

(b) Calling the 'interrupt' from within the 'compare' routine works.
    Should it?  Although this is very convenient for my purposes,
    I would have expected 'interrupt' not to be in scope within the
    'compare' routine.

--
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Laurence G. Yaffe		Internet: lgy@newton.phys.washington.edu
University of Washington	Bitnet:   yaffe@uwaphast.bitnet