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, 11 insertions, 0 deletions

diff --git a/numpy/array_api/_array_object.py b/numpy/array_api/_array_object.py
index ead061882..d322e6ca6 100644
--- a/numpy/array_api/_array_object.py
+++ b/numpy/array_api/_array_object.py
@@ -108,6 +108,17 @@ class Array:
             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(np.array_api.Array) will work.
+    def __array__(self, dtype=None):
+        """
+        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.
+
+        """
+        return np.asarray(self._array, dtype=dtype)
+
     # 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
     # NumPy behavior