On Sun, Mar 25, 2018 at 8:31 PM, Christoph Groth <christ...@grothesque.org> wrote: > That's indeed a bit strange, and I would consider it somewhat of a wart > of the language. But as far as I can tell remaining compatible with the > above behavior does not force us to leak assignments from the outermost > scope of a comprehension. I.e. there's nothing in the language > currently that forces > > listcomp = [x for x in (r := sequence)] > > to leak the name "r". > > Granted, it's a bit strange if in the above line the name "sequence" is > evaluated in class scope but the name "r" is set in the comprehension > scope, but since currently there is no way to assign values to names in > comprehensions this "hybrid" behavior would be backwards-compatible, and > less surprising than leaking "r".
It seems fine in a simple example, but remember, an assignment expression can be used ANYWHERE in an expression. Consider: listcomp = [x for x in obj[r := f()][x + r] ] Which parts happen in the inner scope and which in the outer scope? If 'r' is created in a subscope, it has to be a subscope of the outer scope; if it's not subscoped, it has to be directly in the outer scope. It can't sanely be in the inner scope. ChrisA _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
