This isn't meant as a criticism, however, why use map in place of grep?

my $caller = caller();
push @{"$caller\::ISA"}, grep $_ ne $caller, @_;
[download]

I do use map with the empty return quite often when a list/array requires filtering and transformation because it tends to make me feel warm and fuzzy inside. Multiple maps and greps can become confusing. However, if all you're doing is filtering then grep to be clearer (and I believe faster, too).