Newsgroups: comp.lang.perl
Path: utzoo!utgpu!cunews!bnrgate!bmers145!friedman
From: friedman@chekov.UU.NET (Barry Friedman)
Subject: defined() - bug or feature?
Message-ID: <1991Mar21.142935.11333@bmers145.bnr.ca>
Sender: news@bmers145.bnr.ca
Reply-To: friedman%chekov@uunet.uu.net
Organization: Northern Telecom Ltd.
Date: Thu, 21 Mar 91 14:29:35 GMT

I've noticed the following non-intuitive behaviour of 'defined()':
When a variable is used in a string it becomes defined.

I don't recall any discussion on this.

#!/usr/bin/perl

$a='$b is undefined';
$a='$b is defined' if defined ($b);
print $a,"\n";
print "b is now <$b>","\n";
$a='$b is defined' if defined ($b);
print $a,"\n";
__END__

produces
$b is undefined
b is now <>
$b is defined

--
Barry Friedman                INTERNET: friedman%chekov@uunet.uu.net
Phone: (613) 782-2389         UUCP: ...!uunet!chekov!friedman
Emax Computer Systems Inc.  440 Laurier Ave. W., Ottawa, Ont. Canada K1R 5C4