"Actually it's not quite perfect, since the resulting array also fills up with a pile of undefs"

Couldn't you just filter the result through grep first?

my (@s) = grep $_, m{
   big regex here
}gx;
[download]

Sure it would be better to not have undefs in there in the first place, and you said you know where they will be, but why worry when grep is at disposal. Just a thought, and thanks for the post. :)

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)