TypedDict keys reuse?

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#4,128 8 comments 29 reactions 0 assignees View on GitHub

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
30/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
python
Domain
devtools

Research direction

The issue names no files, tests, or entry points. Start by locating mypy's TypedDict handling and its related tests; determine whether key reuse can be supported while preserving literal validation, then add coverage for the accepted behavior or document that it remains unsupported.

Written by the indexing model from the issue text.

Description

feature priority-1-normal topic-typed-dict

I may be in a need of the following - two TypeDicts with the same keys, one of them created with total=False:

from mypy_extensions import TypedDict

Details = TypedDict('Details', {'name': str, 'age': int, 'address': str})
DetailsSubset = TypedDict('DetailsSubset', {'name': str, 'age': int, 'address': str}, total=False)

Is there a way to reuse the keys instead of having to repeat the {'name': str, 'age': int, address: str} fragment twice?

I can't do

from mypy_extensions import TypedDict

keys = {'name': str, 'age': int, 'address': str}
Details = TypedDict('Details', keys)
DetailsSubset = TypedDict('DetailsSubset', keys, total=False)

Because

% mypy code.py
code.py:4: error: TypedDict() expects a dictionary literal as the second argument
code.py:5: error: TypedDict() expects a dictionary literal as the second argument

(which is quite reasonable, tried that on the off chance it'd work)

Dominant language
Python
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