Merge pull request #9015 from charris/polynomial-ufunc-optout

njsmith · web-flow · commit e87523089129 · 2017-04-28T20:28:29.000-07:00
ENH: Use `__array_ufunc__ = None` in polynomial convenience classes.
diff --git a/doc/release/1.13.0-notes.rst b/doc/release/1.13.0-notes.rst
@@ -419,3 +419,10 @@ greater than ``mmap.ALLOCATIONGRANULARITY``.
 Previously, ``np.real`` and ``np.imag`` used to return array objects when
 provided a scalar input, which was inconsistent with other functions like
 ``np.angle`` and ``np.conj``.
+
+The polynomial convenience classes cannot be passed to ufuncs
+-------------------------------------------------------------
+The ABCPolyBase class, from which the convenience classes are derived, sets
+``__array_ufun__ = None`` in order of opt out of ufuncs. If a polynomial
+convenience class instance is passed as an argument to a ufunc, a ``TypeError``
+will now be raised.
diff --git a/numpy/polynomial/_polybase.py b/numpy/polynomial/_polybase.py
@@ -64,8 +64,8 @@ class ABCPolyBase(object):
     # Not hashable
     __hash__ = None
 
-    # Don't let participate in array operations. Value doesn't matter.
-    __array_priority__ = 1000
+    # Opt out of numpy ufuncs and Python ops with ndarray subclasses.
+    __array_ufunc__ = None
 
     # Limit runaway size. T_n^m has degree n*m
     maxpower = 100
diff --git a/numpy/polynomial/tests/test_classes.py b/numpy/polynomial/tests/test_classes.py
@@ -53,6 +53,7 @@ def test_class_methods():
         yield check_cutdeg, Poly
         yield check_truncate, Poly
         yield check_trim, Poly
+        yield check_ufunc_override, Poly
 
 
 #
@@ -575,5 +576,12 @@ def check_mapparms(Poly):
     assert_almost_equal([1, 2], p.mapparms())
 
 
+def check_ufunc_override(Poly):
+    p = Poly([1, 2, 3])
+    x = np.ones(3)
+    assert_raises(TypeError, np.add, p, x)
+    assert_raises(TypeError, np.add, x, p)
+
+
 if __name__ == "__main__":
     run_module_suite()
