Fredrik Lundh wrote: > Just van Rossum wrote: > >> Why couldn't at least augmented assignment be implicitly rebinding? It >> has been suggested before (in the context of a rebinding operator), but >> I'm wondering, is this also off the table? >> >> def counter(num): >> def inc(): >> num += 1 >> return num >> return inc >> >> Reads very natural to me. It's likely the most frequent example of what >> people try before they learn that rebinding to outer scopes isn't >> allowed. It could Just Work. > > note that most examples of this type already work, if the target type is > mutable, and implement the right operations: > > def counter(num): > num = mutable_int(num) > def inc(): > num += 1 > return num > return inc
I agree with you (and argued it in "scopes vs augmented assignment vs sets" recently) that mutating would be sufficient /if/ the compiler would view augmented assignment as mutations operators : which it doesn't as far as concerns scopes where a variable appears as target only of /augmented/ assignments. Currently, the code you propose above will not work, and whatever your mutable_int() it will result in UnboundLocalError: local variable 'num' referenced before assignment What probably trips you is that the compiler thus makes a choice of interpretation that has no use cases. Cheers, BB _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
