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Refine the copy._SupportsReplace.__replace__ signature #14786

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Merged
srittau merged 6 commits into from
Sep 30, 2025
Merged

Refine the copy._SupportsReplace.__replace__ signature #14786

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0403f9d
Refine the `copy._SupportsReplace.__replace__` signature
jorenham Sep 26, 2025
b93847d
support for asymmetric `__replace__` in `copy.replace`
jorenham Sep 26, 2025
6ba4ca7
`copy.replace` regression test for asymmetric `__replace__`
jorenham Sep 26, 2025
4449936
don't use `ParamSpec` `copy._SupportsReplace`
jorenham Sep 30, 2025
8f09cc4
add comment explaining the use of `Any` in `copy.replace`
jorenham Sep 30, 2025
ce839df
avoid using `Any` in the `copy.replace` tests
jorenham Sep 30, 2025
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11 changes: 6 additions & 5 deletions stdlib/copy.pyi
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Original file line number Diff line number Diff line change
@@ -1,16 +1,17 @@
import sys
from typing import Any, Protocol, TypeVar, type_check_only
from typing_extensions import Self
from typing_extensions import ParamSpec

__all__ = ["Error", "copy", "deepcopy"]

_T = TypeVar("_T")
_SR = TypeVar("_SR", bound=_SupportsReplace)
_Tss = ParamSpec("_Tss")
_RT_co = TypeVar("_RT_co", covariant=True)

@type_check_only
class _SupportsReplace(Protocol):
class _SupportsReplace(Protocol[_Tss, _RT_co]):
# In reality doesn't support args, but there's no other great way to express this.
def __replace__(self, *args: Any, **kwargs: Any) -> Self: ...
def __replace__(self, /, *_: _Tss.args, **changes: _Tss.kwargs) -> _RT_co: ...
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# None in CPython but non-None in Jython
PyStringMap: Any
Expand All @@ -21,7 +22,7 @@ def copy(x: _T) -> _T: ...

if sys.version_info >= (3, 13):
__all__ += ["replace"]
def replace(obj: _SR, /, **changes: Any) -> _SR: ...
def replace(obj: _SupportsReplace[..., _RT_co], /, **changes: Any) -> _RT_co: ...
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class Error(Exception): ...

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