My only point was regarding when you simply want to return a false value to indicate a subroutine failure. Consider the following contrived example where we only want to process strings beginning with a particular pattern:

#!/usr/bin/perl -w
use strict;
my @patterns = (qr/^foo/, qr/^qux/);
my @strings  = ('foo bar', 'bar bar', 'qux bar');
my @stuff;
foreach my $string (@strings){
    if(@stuff = dice_it($string)){
        print "Processing: $string\n";
        process_stuff(@stuff);
    }
}

sub dice_it {
    my $string = shift;
    foreach my $pat (@patterns) {
        return split //, $string if $string =~ /$pat/;
    }
    return undef;
}

sub process_stuff {
    foreach (@_) {
        print "<$_>";
    }
    print "\n";
}
[download]

I'm not suggesting this a terribly common problem (or that the above is a good way to approach this particular example). I just wanted to point out that returning 'undef' as a failure mode isn't always appropriate -- and people who do so may forget that an array containing one undefined element still evaluates to true so they may bang their head for a while before they realize why they are processing the string 'bar bar' and getting a warning. Changing the last line of dice_it() to just a bare 'return' statement alleviates the problem because it returns the 'right' thing depending on context.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.