Sounds like a job for ... File::Find::Rule!

use File::Find::Rule;

my $cnt = scalar find(
  directory =>
  name      => 'class',
  in        => @good_dirs,
);
[download]

That should roughly do what you want, but if not, tweak as you see fit. See. the File::Find::Rule docs for more info on this most marvellous of modules.
HTH

_________
broquaint