True, but then it wouldn't be able to break encapsulation and pull out $other->{_code} to speed things up by avoiding another overloaded &{} dispatch. Then again that's not exactly safe either, but what does one expect for a ten minute one-off example. :)

A better solution might be to ask if UNIVERSAL::can( $other, "to_code" ) and then use that to obtain a coderef from $other (which would be starting to look a bit like duck typing . . .).