If you'll be matching against the same variable
(like $date) multiple times, use the /o operator. That
way Perl will only compile the regex once, not each
time through the loop.
You could also compile such a regex using
the qr operator. Check that out, as well.
Of course, in this case, you might want to just
use eq. :)
If I misunderstood what you're asking, let me know.