The Prime That Wasn't

What's scary here is that PHP returns 0 (meaning no match found) rather than FALSE, which is the error return value of preg_match. It's this attitude of failing silently that makes PHP feel like a dangerous language.<p>Granted, it's smart that PHP does have a default backtrack limit. I believe this would have prevented errors like the django forms DoS vulnerability from a while back.

This pattern is usually attributed to the famous Perl hacker, Abigail. Abigail is also noted as one of the people who popularized the idea of a JAPH. That is a short piece of Perl that prints out "Just another Perl hacker". For instance the very misleadingly commented:<p><pre><code> $; # A lone dollar? =$"; # Pod? $; # The return of the lone dollar? {Just=&#62;another=&#62;Perl=&#62;Hacker=&#62;} # Bare block? =$/; # More pod? print%; # No right operand for %?</code></pre>

The idea behind how this works using regular expressions is very similar to how some C++ template metaprograms work.