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Support TypedDict update() with keyword arguments #6019

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JukkaL opened this issue Dec 6, 2018 · 2 comments
Open

Support TypedDict update() with keyword arguments #6019

JukkaL opened this issue Dec 6, 2018 · 2 comments
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feature topic-typed-dict

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@JukkaL
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JukkaL commented Dec 6, 2018

Things like d.update(x=1, y=2) should be accepted if d is a TypedDict and the keys and values are compatible.
@JukkaL JukkaL mentioned this issue Dec 6, 2018
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JukkaL added a commit that referenced this issue Dec 6, 2018
@JukkaL
Add support for additional TypedDict methods (#6011)
d34d285 
This adds support for these methods through additional plugin hooks:

* `pop`
* `setdefault`
* `update` (positional argument only)
* `__delitem__`

These methods also work and don't need plugin support:

* `copy`
* `has_key` (Python 2 only)
* `viewitems` (Python 2 only)
* `viewkeys` (Python 2 only)
* `viewvalues` (Python 2 only)

The base signatures for all of these methods are defined in 
`mypy_extensions._TypedDict`, which is a stub-only class
only used internally by mypy. It becomes the new fallback
type of all TypedDicts.

Fixes #3843. Fixes #3550.

There's some possible follow-up work that I'm leaving to other PRs,
such as optimizing hook lookup through dictionaries in the default
plugin, documenting the supported methods, and `update` with
keyword arguments (#6019).
@chrahunt chrahunt mentioned this issue Aug 9, 2019
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@jmontleon jmontleon mentioned this issue Jun 15, 2020
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@97littleleaf11 97littleleaf11 mentioned this issue Dec 15, 2021
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@emmatyping
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emmatyping commented Dec 28, 2024 •
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I think this would need to be added as a specification of the standard. I do not see this as allowed anywhere, and currently the update method is annotated as accepting only a TypedDict in typeshed.

Perhaps this should be moved to the typing repo (or I guess CPython)?

@JelleZijlstra
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I don't think this would require a change to the spec. The spec is mostly silent on the update() method (there is some discussion from the ReadOnly PEP at https://typing.readthedocs.io/en/latest/spec/typeddict.html#update-method), but it wouldn't be against the spec to allow update() calls that preserve the type. Pyright also accepts it: https://pyright-play.net/?code=GYJw9gtgBALgngBwJYDsDmUkQWEMoAqiApgCYAiSAxjAFC1UA2AhgM6tQAaAFEQmZRoBKAFy0oEqMxGYUdWqWLAowbgA8ZnUeMlqAdAFcEpZjGLdmAXgCMQ2kA

Perhaps this should be moved to the typing repo (or I guess CPython)?

The CPython issue tracker should only be used for tracking changes to the typing.py runtime. Spec changes should go to the python/typing issue tracker.

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