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Add Protocols for mapping inside dictionary view objects #14574

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Merged
srittau merged 2 commits into from
Aug 18, 2025
Merged

Add Protocols for mapping inside dictionary view objects #14574

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1840a0a
Add Protocols for mapping inside dictionary view objects
Gatsik Aug 13, 2025
1a23f64
Avoid inheritance and explicitly define protocol methods
Gatsik Aug 15, 2025
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4 changes: 4 additions & 0 deletions stdlib/_typeshed/__init__.pyi
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Original file line number Diff line number Diff line change
Expand Up @@ -377,3 +377,7 @@ if sys.version_info >= (3, 14):
# These return annotations, which can be arbitrary objects
AnnotateFunc: TypeAlias = Callable[[Format], dict[str, AnnotationForm]]
EvaluateFunc: TypeAlias = Callable[[Format], AnnotationForm]

# Suitable for dictionary view objects
class Viewable(Sized, Iterable[_KT_co], Protocol): ...
class SupportsGetItemViewable(Viewable[_KT], SupportsGetItem[_KT, _VT_co], Protocol): ...
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@srittau srittau Aug 15, 2025

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Could you move these up to the other Supports* protocols?

Also, in typeshed (or at least in the _typeshed module) we have a slight preference for spelling out the methods supported in protocol, instead of deriving from other protocols, see for example SupportsItemAccess above. This makes it slightly easier for users to understand what methods are needed to fulfill a protocol instead of traversing through the class hierarchy.

10 changes: 5 additions & 5 deletions stdlib/typing.pyi
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Expand Up @@ -5,7 +5,7 @@ import collections # noqa: F401 # pyright: ignore[reportUnusedImport]
import sys
import typing_extensions
from _collections_abc import dict_items, dict_keys, dict_values
from _typeshed import IdentityFunction, ReadableBuffer, SupportsKeysAndGetItem
from _typeshed import IdentityFunction, ReadableBuffer, SupportsGetItemViewable, SupportsKeysAndGetItem, Viewable
from abc import ABCMeta, abstractmethod
from re import Match as Match, Pattern as Pattern
from types import (
Expand Down Expand Up @@ -703,11 +703,11 @@ class MutableSet(AbstractSet[_T]):
def __isub__(self, it: AbstractSet[Any]) -> typing_extensions.Self: ...

class MappingView(Sized):
def __init__(self, mapping: Mapping[Any, Any]) -> None: ... # undocumented
def __init__(self, mapping: Sized) -> None: ... # undocumented
def __len__(self) -> int: ...

class ItemsView(MappingView, AbstractSet[tuple[_KT_co, _VT_co]], Generic[_KT_co, _VT_co]):
def __init__(self, mapping: Mapping[_KT_co, _VT_co]) -> None: ... # undocumented
def __init__(self, mapping: SupportsGetItemViewable[_KT_co, _VT_co]) -> None: ... # undocumented
def __and__(self, other: Iterable[Any]) -> set[tuple[_KT_co, _VT_co]]: ...
def __rand__(self, other: Iterable[_T]) -> set[_T]: ...
def __contains__(self, item: object) -> bool: ...
Expand All @@ -720,7 +720,7 @@ class ItemsView(MappingView, AbstractSet[tuple[_KT_co, _VT_co]], Generic[_KT_co,
def __rxor__(self, other: Iterable[_T]) -> set[tuple[_KT_co, _VT_co] | _T]: ...

class KeysView(MappingView, AbstractSet[_KT_co]):
def __init__(self, mapping: Mapping[_KT_co, Any]) -> None: ... # undocumented
def __init__(self, mapping: Viewable[_KT_co]) -> None: ... # undocumented
def __and__(self, other: Iterable[Any]) -> set[_KT_co]: ...
def __rand__(self, other: Iterable[_T]) -> set[_T]: ...
def __contains__(self, key: object) -> bool: ...
Expand All @@ -733,7 +733,7 @@ class KeysView(MappingView, AbstractSet[_KT_co]):
def __rxor__(self, other: Iterable[_T]) -> set[_KT_co | _T]: ...

class ValuesView(MappingView, Collection[_VT_co]):
def __init__(self, mapping: Mapping[Any, _VT_co]) -> None: ... # undocumented
def __init__(self, mapping: SupportsGetItemViewable[Any, _VT_co]) -> None: ... # undocumented
def __contains__(self, value: object) -> bool: ...
def __iter__(self) -> Iterator[_VT_co]: ...

Expand Down
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