$reg = qr'foo';
$str = 'foo';
$str2 = '(?-xism:foo)';
$reg_ref = \$reg;
$str_ref = \$str;
$str2_ref = \$str2;
print "$reg -> $reg_ref\n";
print "$str -> $str_ref\n";
print "$str2 -> $str2_ref\n";