#!/usr/bin/perl

my @strings = ('testing','','testing','testing');

foreach my $string (@strings) {

    print "\nSTRING: $string\n";

    my $string2 = 'http';
    $string2 =~ /^h(.*)/o;

    my $q = $string;
    my $test = 'testing';
    warn $test =~ /\Q$q\E/;
}

[download]

I finally got to the bottom of the problem I reported at http://www.perlmonks.org/?node_id=867059 (thx to everyone who commented), and I distilled it to the above test case.

Here's what I think is happening. If you have a an /o regex with a capture clause and it captures something, and then you run a a second regex with a variable, but it set to '', then it uses the first compiled regex instead (and thereafter), and doesn't match as you'd expect as a result.

In this example, You'd expect line 14 to warn 1 then nothing, then 1 twice. Instead, you get 1, then nothing the rest of the time.

I'm running v5.8.9 on FreeBSD 7.0. FWIW, I also filed a perlbug here: http://rt.perl.org/rt3/Ticket/Display.html?id=78564

In reply to Perl bug or feature? by yegg

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