Changes to TensorConstantSignature.

theano/tensor/basic.py

@@ -770,13 +770,29 @@ class TensorVariable(Variable, _tensor_py_operators):
     """Subclass to add the tensor operators to the basic `Variable` class."""
 
 class TensorConstantSignature(tuple):
+    """A Signature object for comparing TensorConstant instances
+
+    An instance is a pair: (Type instance, ndarray).
+    """
     def __eq__(self, other):
-        (a, b), (x,y) = self, other
+        try:
+            (t0, d0), (t1,d1) = self, other
+        except:
+            return False
         #N.B. compare shape to ensure no broadcasting in ==
-        return (x == a) and (b.shape == y.shape) and (numpy.all(b == y)) 
+        return (t0 == t1) and (d0.shape == d1.shape) \
+                and (self.sum == other.sum) and (numpy.all(d0 == d1)) 
     def __hash__(self):
-        a, b = self
-        return hashtype(self) ^ hash(a) ^ hash(b.shape)
+        t, d = self
+        return hashtype(self) ^ hash(t) ^ hash(d.shape) ^ hash(self.sum)
+    def _get_sum(self):
+        try:
+            return self._sum
+        except:
+            self._sum = self[1].sum()
+        return self._sum
+    sum = property(_get_sum)
+
 
 class TensorConstant(Constant, _tensor_py_operators):
     """Subclass to add the tensor operators to the basic `Constant` class.