✨: make HasNamespace

Signed-off-by: Nathaniel Starkman <[email protected]>

Author: nstarman

.gitignore

@@ -22,3 +22,6 @@ venv/
 
 # Build docs
 /src/array_api_typing/_version.py
+
+# Mac files
+.DS_Store

pyproject.toml

@@ -25,7 +25,9 @@
     "Topic :: Scientific/Engineering",
     "Typing :: Typed",
   ]
-  dependencies = []
+  dependencies = [
+    "typing-extensions>=4.14.0",
+  ]
 
   [project.urls]
     Repository = "https://github.com/data-apis/array-api-typing"

src/array_api_typing/__init__.py

@@ -1,5 +1,6 @@
 """Static typing support for the array API standard."""
 
-__all__ = ()
+__all__ = ["HasNamespace"]
 
 from ._version import version as __version__ , version_tuple as __version_tuple__
+from ._namespace import HasNamespace

src/array_api_typing/_namespace.py

@@ -0,0 +1,33 @@
+"""Static typing support for the array API standard."""
+
+__all__ = ["HasNamespace"]
+
+from types import ModuleType
+from typing import Protocol, final
+from typing_extensions import TypeVar
+
+T = TypeVar("T", bound=object, default=ModuleType)  # PEP 696 default
+
+
+@final
+class HasNamespace(Protocol[T]):  # type: ignore[misc]  # see python/mypy#17288
+    """Protocol for classes that have an `__array_namespace__` method.
+
+    This is for type-annotating objects that should
+
+    Example:
+    >>> import array_api_typing as xpt
+    >>>
+    >>> class MyArray:
+    ...     def __array_namespace__(self):
+    ...         return object()
+    >>>
+    >>> x = MyArray()
+    >>> def has_namespace(x: xpt.HasNamespace) -> bool:
+    ...     return hasattr(x, "__array_namespace__")
+    >>> has_namespace(x)
+    True
+
+    """
+
+    def __array_namespace__(self, /, *, api_version: str | None = None) -> T: ...  # noqa: PLW3201