ENH: Add arrayproxy.ArrayLike protocol

Author: effigies

nibabel/arrayproxy.py

@@ -25,11 +25,13 @@
 
 See :mod:`nibabel.tests.test_proxy_api` for proxy API conformance checks.
 """
+import typing as ty
 import warnings
 from contextlib import contextmanager
 from threading import RLock
 
 import numpy as np
+import numpy.typing as npt
 
 from . import openers
 from .fileslice import canonical_slicers, fileslice
@@ -53,7 +55,25 @@
 KEEP_FILE_OPEN_DEFAULT = False
 
 
-class ArrayProxy:
+@ty.runtime_checkable
+class ArrayLike(ty.Protocol):
+    """Protocol for numpy ndarray-like objects
+
+    This is more stringent than :class:`numpy.typing.ArrayLike`, but guarantees
+    access to shape, ndim and slicing.
+    """
+
+    shape: tuple[int, ...]
+    ndim: int
+
+    def __array__(self, dtype: npt.DTypeLike | None = None, /) -> npt.NDArray:
+        ...
+
+    def __getitem__(self, key, /) -> npt.NDArray:
+        ...
+
+
+class ArrayProxy(ArrayLike):
     """Class to act as proxy for the array that can be read from a file
 
     The array proxy allows us to freeze the passed fileobj and header such that