I wonder, is that a design accident or intended? you can assign to a typeglob slot (assigning a specific ref to that typeglob), but you cannot undef its value, you have to destroy the whole glob. You cannot assign e.g. an 'undefined subref' to a CODE slot, because... no such thing. Something undef is not a CODE ref.
Did you get told the rationale behind that? Does anybody know? Cloning a typeglob to get rid of one entry in it looks like "useless use of hoops" to me. IMHO there should be a syntax to remove slots, keys, values and all, as delete does with plain hashes.
--shmem
_($_=" "x(1<<5)."?\n".q·/)Oo. G°\ /
/\_¯/(q /
---------------------------- \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}