If your program needs to be that secure, write it in some other language than perl.

Sorry, but that's just wrong. "Security" is not gained by hiding your source code. That's a temperary measure, at best. Perl just happens to make this problem more obvious.

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I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

Note: All code is untested, unless otherwise stated