On Wed, Dec 23, 2020 at 11:16 PM Brandt Bucher <brandtbucher@gmail.com> wrote:
I didn't participate in the mailing list discussions for PEP 637, but I have become somewhat involved in the reference implementation and final revisions. While reviewing the PEP, I noticed what I think is a missed opportunity to finally allow empty subscripting (`obj[]`). It seems to me to be a natural consequence of the `obj[*a]` and `obj[**k]` syntax which the PEP proposes, and I'm quite surprised that the PEP still outlaws it (the latest revision has language that says we're punting on this, but I'd like to change that).

I'm -0.5 on allowing that now.

There was SOME discussion of this in the long threads, but not any strong consensus as I read it.

However, it has no clear use *outside of type hints*, and hence is a slight invitation to abuse or misunderstanding.  I would rather it be its own proposal, or part of some more general proposal around type hints.  Not allowing the empty subscript in the initial implementation does not preclude allowing it later when it has an actual use case that has been presented a bit more formally than in this email.

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