ENH: Add __array__ to the array_api Array object

This is *NOT* part of the array API spec (so it should not be relied on for
portable code). However, without this, np.asarray(np.array_api.Array) produces
an object array instead of doing the conversion to a NumPy array as expected.
This would work once np.asarray() implements dlpack support, but until then,
it seems reasonable to make the conversion work.

Note that the reverse, calling np.array_api.asarray(np.array), already works
because np.array_api.asarray() is just a wrapper for np.asarray().

1 files changed, 7 insertions, 0 deletions

diff --git a/numpy/array_api/tests/test_array_object.py b/numpy/array_api/tests/test_array_object.py
index deab50693..b980bacca 100644
--- a/numpy/array_api/tests/test_array_object.py
+++ b/numpy/array_api/tests/test_array_object.py
@@ -315,3 +315,10 @@ def test_array_properties():
     assert a.mT.shape == (1, 3, 2)
     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