Take a lesson - always write parsers in C and then execute them as root, and be sure to send as much malicious content to them as possible. Bonus points for hooking it up to the internet.
Addicionally ignore all the advices given by the Algol community since the 1960's, in spite of the fact the customers were more than happy with the output of their compilers.
Also, change your code often and hire/fire programmers at a high rate.