There are a few ways this script is atypical for me. The brainwashing has worked -- for the first time I can remember, I actually started a script with
use strict. I don't think it saved me this time, but it was simple enough to obey its strictures.
This is the first time I've used the DirHandle module. Combined with
grep, it proved an elegant way to get the filenames to work on.
And actually, the use of
grepto filter lists is a fairly new technique, which I think I picked up in my Perl 6 experiments.
By the way, once the full table was generated, I had the bug's cause pinned down in about twenty seconds.