The perl regular expression engine could be seen as an example of "worse is better" (I mean it as a compliment ;-) It might not be the prettiest from some theoretical point of view, it might have pathological cases, but it exists and gets the job done. Sure, it would be great if it had no pathological cases. I have to say that I have never encountered one in real life, but I always feel a bit uneasy letting users of a website run regular expressions via a CGI script due to the risk that they will input a pathological expression just for fun (you can set a timeout, but it's a bit of a pain).
in reply to Perl regexp matching is slow??