One other thing to note is that anything in the symbol table (scalar, array, hash, format, or filehandle besides sub) will show up in *stash. The trick is to see if there's anything defined for the CODE slot of the glob:

foreach (keys %{*stash} ) {
    next if (defined $internal{$_} || /^_/);
    my $sub = *{$stash->{$_}}{CODE};
    next unless defined &$sub;    
    push(@methods,$_);
}
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That might require a little tweaking, but you'll learn a lot. :) Oh, and if you think you'll eventually inherit from one of these driver classes, you might want to have mk_provides call SUPER() and weed out duplicates. Could come in handy.