86 lines
2.5 KiB
Python
86 lines
2.5 KiB
Python
"""Backward compatibility for newer/less buggy typing features.
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## Important
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Import from here to avoid introducing a runtime dependency on [`typing_extensions`]
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## Notes
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- `TypeVar` defaults
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- https://typing.python.org/en/latest/spec/generics.html#type-parameter-defaults
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- https://peps.python.org/pep-0696/
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- `@deprecated`
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- https://docs.python.org/3/library/warnings.html#warnings.deprecated
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- https://typing.python.org/en/latest/spec/directives.html#deprecated
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- https://peps.python.org/pep-0702/
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[`typing_extensions`]: https://github.com/python/typing_extensions
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"""
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from __future__ import annotations
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# ruff: noqa: ARG001, ANN202, N802
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import sys
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from typing import TYPE_CHECKING, Any
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if TYPE_CHECKING:
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from typing import Callable
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if sys.version_info >= (3, 13):
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from typing import TypeVar
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from warnings import deprecated
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else:
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from typing_extensions import TypeVar, deprecated
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if sys.version_info >= (3, 11):
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from typing import Never, assert_never
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else:
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from typing_extensions import Never, assert_never
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_Fn = TypeVar("_Fn", bound=Callable[..., Any])
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else: # pragma: no cover
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if sys.version_info >= (3, 13):
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from typing import TypeVar
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from warnings import deprecated
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else:
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from typing import TypeVar as _TypeVar
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def TypeVar(
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name: str,
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*constraints: Any,
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bound: Any | None = None,
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covariant: bool = False,
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contravariant: bool = False,
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**kwds: Any,
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):
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return _TypeVar(
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name,
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*constraints,
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bound=bound,
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covariant=covariant,
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contravariant=contravariant,
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)
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def deprecated(message: str, /) -> Callable[[_Fn], _Fn]:
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def wrapper(func: _Fn, /) -> _Fn:
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return func
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return wrapper
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_ASSERT_NEVER_REPR_MAX_LENGTH = 100
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_BUG_URL = (
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"https://github.com/narwhals-dev/narwhals/issues/new?template=bug_report.yml"
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)
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def assert_never(arg: Never, /) -> Never:
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value = repr(arg)
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if len(value) > _ASSERT_NEVER_REPR_MAX_LENGTH:
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value = value[:_ASSERT_NEVER_REPR_MAX_LENGTH] + "..."
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msg = (
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f"Expected code to be unreachable, but got: {value}.\n"
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f"Please report an issue at {_BUG_URL}"
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)
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raise AssertionError(msg)
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__all__ = ["TypeVar", "assert_never", "deprecated"]
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