If I were using source filters, I would be very careful to write easy-to-parse Perl.
The trouble is, even that's not good enough. Someone posted a snippet on p5p in this thread, showing how the current incarnation of Switch gets tripped up by thinking it's in a string instead of code, or vice versa.
The trouble was that the snippet's only sin was that the word 'case' appeared in a comment... Something as arbitrary as that just gives me the willies.
- another intruder with the mooring in the heart of the Perl