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PEP 728: Fix some small mistakes #4554

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Merged
merged 2 commits into from
Aug 18, 2025
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PEP 728: Fix some small mistakes #4554

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e8bdea8
PEP 728: Minor fixes
JelleZijlstra Aug 16, 2025
1095c65
one more
JelleZijlstra Aug 18, 2025
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8 changes: 4 additions & 4 deletions peps/pep-0728.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -335,7 +335,7 @@ extra items::
name: str

def f(movie: Movie) -> None:
del movie["name"] # Not OK. The value type of 'name' is 'Required[int]'
del movie["name"] # Not OK. The value type of 'name' is 'Required[str]'
del movie["year"] # OK. The value type of 'year' is 'NotRequired[int]'

Interaction with ``Unpack``
Expand Down Expand Up @@ -726,8 +726,8 @@ with signatures matching ``dict[str, VT]``
reveal_type(not_required_num_dict.popitem()) # OK. Revealed type is 'tuple[str, int]'

def f(not_required_num_dict: IntDictWithNum, key: str):
not_required_num_dict[key] = 42 # OK
del not_required_num_dict[key] # OK
not_required_num_dict[key] = 42 # OK
del not_required_num_dict[key] # OK

:ref:`Notes on indexed accesses <pep728-type-narrowing>` from the previous section
still apply.
Expand All @@ -741,7 +741,7 @@ because such dict can be a subtype of dict::
def f(might_not_be_a_builtin_dict: dict[str, int]):
int_dict: IntDict = might_not_be_a_builtin_dict # Not OK

not_a_builtin_dict: CustomDict = {"num": 1}
not_a_builtin_dict = CustomDict({"num": 1})
f(not_a_builtin_dict)

Runtime behavior
Expand Down