sierrathedog04 has asked for the wisdom of the Perl Monks concerning the following question:

Last January I posted a question on how to force Perl to check at compile time that the subroutines I call exist.

The extremely wise Tye advised to "sort your subroutines in reverse topological order (so subroutines are declared before you use them), then call all your subroutines using barewords."

Recently I was using, and I made the mistake of properly spelling the word "referrer()" instead spelling it "referer()" as demands. The script compiled fine and gave only run-time errors telling me that referrer() does not exist.

Since I did not write I cannot sort it in topological order. How can I force Perl to check that the functions I call in the CPAN modules exist?