(🐞) Check `__setitem__` and `__getitem__` for `TypedDict`s
Open
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feature
priority-2-low
topic-typed-dict
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
from typing import TypedDict
class A(TypedDict):
x: int
a: A
a.__setitem__('x', '') # no error
b: int = a.__getitem__('x') # error: Incompatible types in assignment (expression has type "object", variable has type "int")
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the TypedDict example through mypy and locating the handling of setitem and getitem for TypedDicts. Trace how the key and value types are inferred, then verify that assigning a string to x is rejected and reading x is treated as int.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 38/100