Remove __array__

array_api_strict/_array_object.py

@@ -125,28 +125,17 @@ def __repr__(self: Array, /) -> str:
             mid = np.array2string(self._array, separator=', ', prefix=prefix, suffix=suffix)
         return prefix + mid + suffix
 
-    # This function is not required by the spec, but we implement it here for
-    # convenience so that np.asarray(array_api_strict.Array) will work.
+    # Disallow __array__, meaning calling `np.func()` on an array_api_strict
+    # array will give an error. If we don't explicitly disallow it, NumPy
+    # defaults to creating an object dtype array, which would lead to
+    # confusing error messages at best and surprising bugs at worst.
+    #
+    # The alternative of course is to just support __array__, which is what we
+    # used to do. But this isn't actually supported by the standard, so it can
+    # lead to code assuming np.asarray(other_array) would always work in the
+    # standard.
     def __array__(self, dtype: None | np.dtype[Any] = None, copy: None | bool = None) -> npt.NDArray[Any]:
-        """
-        Warning: this method is NOT part of the array API spec. Implementers
-        of other libraries need not include it, and users should not assume it
-        will be present in other implementations.
-
-        """
-        # copy keyword is new in 2.0.0; for older versions don't use it
-        # retry without that keyword.
-        if np.__version__[0] < '2':
-            return np.asarray(self._array, dtype=dtype)
-        elif np.__version__.startswith('2.0.0-dev0'):
-            # Handle dev version for which we can't know based on version
-            # number whether or not the copy keyword is supported.
-            try:
-                return np.asarray(self._array, dtype=dtype, copy=copy)
-            except TypeError:
-                return np.asarray(self._array, dtype=dtype)
-        else:
-            return np.asarray(self._array, dtype=dtype, copy=copy)
+        raise ValueError("Conversion from an array_api_strict array to a NumPy ndarray is not supported")
 
     # These are various helper functions to make the array behavior match the
     # spec in places where it either deviates from or is more strict than

array_api_strict/tests/test_array_object.py

@@ -342,13 +342,6 @@ def test_array_properties():
     assert isinstance(b.mT, Array)
     assert b.mT.shape == (3, 2)
 
-def test___array__():
-    a = ones((2, 3), dtype=int16)
-    assert np.asarray(a) is a._array
-    b = np.asarray(a, dtype=np.float64)
-    assert np.all(np.equal(b, np.ones((2, 3), dtype=np.float64)))
-    assert b.dtype == np.float64
-
 def test_allow_newaxis():
     a = ones(5)
     indexed_a = a[None, :]