chore(typing): Add _typing_compat.py

- Mentioned in (#2391 (comment))
- Needed again for #2572

Author: dangotbanned

narwhals/_typing_compat.py

@@ -0,0 +1,59 @@
+from __future__ import annotations
+
+# ruff: noqa: ARG001, ANN202, N802
+import sys
+from typing import TYPE_CHECKING
+from typing import Any
+
+if TYPE_CHECKING:
+    from typing import Callable
+    from typing import Protocol as Protocol38
+
+    if sys.version_info >= (3, 13):
+        from typing import TypeVar
+        from warnings import deprecated
+    else:
+        from typing_extensions import TypeVar
+        from typing_extensions import deprecated
+
+    _Fn = TypeVar("_Fn", bound=Callable[..., Any])
+
+
+else:  # pragma: no cover
+    if sys.version_info >= (3, 13):
+        from typing import TypeVar
+        from warnings import deprecated
+    else:
+        from typing import TypeVar as _TypeVar
+
+        def TypeVar(
+            name: str,
+            *constraints: Any,
+            bound: Any | None = None,
+            covariant: bool = False,
+            contravariant: bool = False,
+            **kwds: Any,
+        ):
+            return _TypeVar(
+                name,
+                *constraints,
+                bound=bound,
+                covariant=covariant,
+                contravariant=contravariant,
+            )
+
+        def deprecated(message: str, /) -> Callable[[_Fn], _Fn]:
+            def wrapper(func: _Fn, /) -> _Fn:
+                return func
+
+            return wrapper
+
+    # TODO @dangotbanned: Remove after dropping `3.8` (#2084)
+    # - https://github.com/narwhals-dev/narwhals/pull/2064#discussion_r1965921386
+    if sys.version_info >= (3, 9):
+        from typing import Protocol as Protocol38
+    else:
+        from typing import Generic as Protocol38
+
+
+__all__ = ["Protocol38", "TypeVar", "deprecated"]