[Python-Dev] Accepting PEP 572, Assignment Expressions (original) (raw)

Guido van Rossum guido at python.org
Fri Jul 13 10:50:51 EDT 2018

Also nobody had a use case.

On Fri, Jul 13, 2018 at 6:57 AM Chris Angelico <rosuav at gmail.com> wrote:

On Fri, Jul 13, 2018 at 11:36 PM, Random832 <random832 at fastmail.com> wrote: > On Wed, Jul 11, 2018, at 20:10, Guido van Rossum wrote: >> As anticippated, after a final round of feedback I am hereby accepting PEP >> 572, Assignment Expressions: https://www.python.org/dev/peps/pep-0572/ > > I know everyone else is probably sick of discussing this (I somehow completely missed the discussion until it was almost done) but I have a question... > > Why does this not allow assignment to attributes and subscripts? I think this is, at least, surprising enough that there should be a rationale section explaining it in the PEP. As it is, it's barely even explicitly stated, other than the use of 'NAME' in a few places and an offhand mention "and [the assignment statement] can assign to attributes and subscripts." > > It was discussed at some length, yes. Assignment to arbitrary targets would also mean permitting iterable unpacking, which is not desired ("x, y := 3, 4"??), and there weren't enough use-cases for attribute/item assignment to justify creating a rule of "you can assign to any single target, but can't unpack". In the future, if such use-cases are found, the grammar can be expanded. > ChrisA _________________________ Python-Dev mailing list Python-Dev at python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/guido%40python.org

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