#!/usr/bin/perl
use strict;
use warnings;

my %qrs = (
    string1  => 'foo',
    string2  => '(xism)',
    regex    => qr/foo/,
    'regex?' => '(?-xism:foo)',
);

while( my( $key, $regex ) = each %qrs ) {
    print "'$key' ";
    print $regex =~ /\(\?\-xism:/
        ? 'YES: '
        : 'no: ';
    print $regex;

    print ' (and matches)' if 'foo' =~/$regex/;
    print "\n";
}