PEP 728: Incorporate feedback since last revision

[PIG208]

• Mention indexed accesses and assignments with arbitrary keys, per Carl's feedback.

• Prepare for submission by clearing the "open issues" sections, with edits when needed.

• Include a reference to a prior discussion on @final addressing Victorien feedback (https://discuss.python.org/t/pep-728-typeddict-with-typed-extra-items/45443/138).

• Update reference implementations.

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📚 Documentation preview 📚: https://pep-previews--4380.org.readthedocs.build/

[Viicos]

Thanks for addressing part of my feedback. Regarding my other points:

Alternatively, the PEP could emphasize on the fact that closed typed dictionaries are only relevant in a context where assignability of arguments to parameters is involved (as “simple” assignments (a: = value) seems to be special cased)

I'll try to get confirmation about this but it's maybe not worth being mentioned in the PEP.

It is stated that closed=True is equivalent to extra_items=Never. Does this mean that closed=False (the default) is equivalent to extra_items=object? This currently not the case (playground)

I'm not sure how this could be clarified, but it does look confusing. It might be related to my first point though, as the playground example uses "simple" assignments.

[PIG208]

Thanks for the reviews and followups! Pushed a new revision.

Re: @Viicos follow-ups

I think the special case you mentioned (also discussed in this section) is a result of TypedDicts following the existing structural assignabillity rules.

This section on extra_items shows some examples where this special case no longer applies, but only when extra_items is specified.

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The intention of having closed=False is to preserve the current TypedDict behavior (which includes the special check during construction). This part is addressed in a paragraph from this section:

When neither extra_items nor closed=True is specified, the TypedDict
is assumed to allow non-required extra items of value type ReadOnly[object]
during inheritance or assignability checks. This preserves the existing behavior
of TypedDict.

I think we can also mention that closed=False is assumed here, and the check for extra keys during construction (this check is from the current typing spec).

[Andrej730]

Noticed a small typo :

peps/peps/pep-0728.rst

Line 728 in 95793de

Practiaclly, the key collision with a regular key can be mitigated with

Also, isn't it the same thing mentioned twice?

peps/peps/pep-0728.rst

Lines 206 to 208 in 95793de

	The alternative inline syntax is also supported::
	Movie = TypedDict("Movie", {"name": str}, extra_items=bool)

peps/peps/pep-0728.rst

Lines 236 to 238 in 95793de

	``extra_items`` is also supported with the functional syntax::
	Movie = TypedDict("Movie", {"name": str}, extra_items=int | None)

[PIG208]

Thanks! Pushed another update to address @Andrej730's comments.

[JelleZijlstra]

Thanks! I just found that this has already been submitted to the Typing Council (python/typing-council#22); I'll ping the other members so we can finally come to a decision.