It is very ugly and it is not very error prone (who knows what changes in regexp syntax can be expected in perl 5.10.0). It is better either to use already mentioned quotemeta or to escape string with \Q and \E in regexp. Example:

my $string = "some unsafe chars";

.... =~ /\Q$string\E/;
[download]

It is exactly equivalent to

my $string = "some unsafe chars";
my $temp = quotemeta $string;

.... =~ /$temp/;
[download]

See perlre for more info.

--
Ilya Martynov (http://martynov.org/)