Note that the (?{ code }) constructs in regexes are also safe from interpolation in /$regex/ except when you explicitly use re 'eval'

But that wasn't originally the case when that feature was first to be released. I argued with Ilya for a few rounds on P5P, then decided he wasn't listening. He kept saying "but they should untaint their regex" like that was even possible by mortals.

So I simply took the position that I would personally and immediately file a CERT bug against Perl 5.00X (whatever it was) the moment it came out. Oddly enough, he "invented" "use re 'eval'" about a day after that. {grin}