On 27 June 2018 at 15:39, Nick Coghlan <ncogh...@gmail.com> wrote: > However, PEP 572 in its current form takes the position "parent local > scoping is sufficiently useful to make it a required pre-requisite for > adding assignment expressions, but not useful enough to expose as a > new scope declaration primitive", and I've come to the view that it > really is the "A+B=MAGIC!" aspect of the current proposal that bothers > me, whereas "A+B implies C for <pragmatic reasons>" doesn't bother me > any more than the implicit non-local references introduced as part of > the original lexical scoping changes bother me.
>From my reading, PEP 572 takes the position that "parent local scoping" is what people expect from assignment expressions *in comprehensions* and it's useful enough that there is no reason not to make that the behaviour. The behaviour isn't generally useful enough to be worth exposing as a primitive (it's not even useful enough for the PEP to give it an explicit name!) so it's just a special case for assignment expressions in comprehensions/generators. That seems to me like a classic example of practicality beating purity. Paul _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
