You say mod_perl here, but what you really mean is Apache::Registry, just one of the many mod_perl modules, and you're relying on the trick that your code is getting wrapped into a giant subroutine, which may not necessarily be true in future implementations of Apache::Registry.

Your trick doesn't work for mod_perl handlers in general, hence my warning on the original code.

-- Randal L. Schwartz, Perl hacker