Fix attribute access for __array_function__. (#309)

sparse/_sparse_array.py

@@ -229,6 +229,7 @@ def __array__(self, **kwargs):
     def __array_function__(self, func, types, args, kwargs):
         import sparse as module
 
+        sparse_func = None
         try:
             submodules = getattr(func, "__module__", "numpy").split(".")[1:]
             for submodule in submodules:
@@ -242,9 +243,19 @@ def __array_function__(self, func, types, args, kwargs):
         try:
             sparse_func = getattr(type(self), func.__name__)
         except AttributeError:
-            return NotImplemented
+            pass
 
-        if not isinstance(sparse_func, Callable):
-            return getattr(self, func.__name__)
+        if (
+            not isinstance(sparse_func, Callable)
+            and len(args) == 1
+            and len(kwargs) == 0
+        ):
+            try:
+                return getattr(self, func.__name__)
+            except AttributeError:
+                pass
+
+        if sparse_func is None:
+            return NotImplemented
 
         return sparse_func(*args, **kwargs)

sparse/tests/test_array_function.py

@@ -66,3 +66,12 @@ def test_ternary(func, arg_order):
     args = [(x, y)[i] for i in arg_order]
     yy = func(*args)
     assert_eq(xx, yy)
+
+
+@pytest.mark.parametrize("func", [np.shape, np.size, np.ndim])
+def test_property(func):
+    y = sparse.random((50, 50), density=0.25)
+    x = y.todense()
+    xx = func(x)
+    yy = func(y)
+    assert xx == yy