I'll spend more time on this later, but I need to point out now that the regexes that use [:alnum:] are broken.

qr/[:alnum:]/;    # /[almnu:]/
qr/[[:alnum:]]/;  # /[[:alnum:]]/
[download]

See? Also, why the POSIX class and not its simpler \w equivalent?

japhy -- Perl and Regex Hacker