> On Jul 2, 2018, at 8:34 AM, Steven D'Aprano <st...@pearwood.info> wrote:
Guido has decided — and despite my concerns, I’m going to enjoy my new loop-and-a half construct:-) But a comment on this: > comprehension are no more special than > assignments inside any other expression. They bind in the current scope, > same as always, and keep the sensible identity that these two > expressions are exactly equivalent in their visible semantics: > > [x:=0, x:=1, x:=2] > > [x:=i for i in (0, 1, 2)] > > including assignments. Sure — and I don’t think that’s confusing. However, generator expressions ( why don’t we call them generator comprehensions?) are a different story, as they may be run at some arbitrary time in the future. This hasn’t been an issue (except for the loop variable, which has been addressed) because: 1) Much of the time, the gen_ex is run right away, in-line. 2) There aren’t many ways to manipulate the local namespace in a gen_ex. With assignment expressions, it will be much easier to manipulate the local namespace, so there is room for some real confusion here. So a real local namespace gen_exp (and comprehensions, for consistency) would be nice. However, that ship has pretty much sailed. Will it end up being a common problem? Probably not, because (a) is still the case, and := will be used infrequently, and hopefully with unlikely to clash names. And as for all the other languages that have assignment expressions? Do they have constructs like generator expressions? -CHB _______________________________________________ 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
