Merge pull request numpy#3905 from charris/backport-1.8-3900

Backport 1.8 3900

Author: charris

numpy/ma/core.py

@@ -930,6 +930,9 @@ def __call__ (self, a, b, *args, **kwargs):
         with np.errstate():
             np.seterr(divide='ignore', invalid='ignore')
             result = self.f(da, db, *args, **kwargs)
+        # check it worked
+        if result is NotImplemented:
+            return NotImplemented
         # Case 1. : scalar
         if not result.ndim:
             if m:
@@ -999,6 +1002,9 @@ def outer (self, a, b):
             return masked
         (da, db) = (getdata(a), getdata(b))
         d = self.f.outer(da, db)
+        # check it worked
+        if d is NotImplemented:
+            return NotImplemented
         if m is not nomask:
             np.copyto(d, da, where=m)
         if d.shape:
@@ -1065,6 +1071,9 @@ def __call__(self, a, b, *args, **kwargs):
         with np.errstate():
             np.seterr(divide='ignore', invalid='ignore')
             result = self.f(da, db, *args, **kwargs)
+        # check it worked
+        if result is NotImplemented:
+            return NotImplemented
         # Get the mask as a combination of ma, mb and invalid
         m = ~umath.isfinite(result)
         m |= ma

numpy/ma/tests/test_core.py

@@ -1662,6 +1662,27 @@ def test_ndarray_mask(self):
         assert_equal(test.mask, control.mask)
         self.assertTrue(not isinstance(test.mask, MaskedArray))
 
+    def test_treatment_of_NotImplemented(self):
+        "Check any NotImplemented returned by umath.<ufunc> is passed on"
+        a = masked_array([1., 2.], mask=[1, 0])
+        # basic tests for _MaskedBinaryOperation
+        assert_(a.__mul__('abc') is NotImplemented)
+        assert_(multiply.outer(a, 'abc') is NotImplemented)
+        # and for _DomainedBinaryOperation
+        assert_(a.__div__('abc') is NotImplemented)
+
+        # also check explicitly that rmul of another class can be accessed
+        class MyClass(str):
+            def __mul__(self, other):
+                return "My mul"
+
+            def __rmul__(self, other):
+                return "My rmul"
+
+        me = MyClass()
+        assert_(me * a == "My mul")
+        assert_(a * me == "My rmul")
+
 #------------------------------------------------------------------------------
 
 class TestMaskedArrayInPlaceArithmetics(TestCase):