Added a check that doesn't add the '{}' part when __props__ is an empty tuple in __str__.

theano/gof/op.py

@@ -586,6 +586,9 @@ class Op(utils.object2, PureOp, CLinkerOp):
 
     def __str__(self):
         if hasattr(self, '__props__'):
+            if len(self.__props__) == 0:
+                return "%s" % (self.__class__.__name__, ", ".join("%s=%r"))
+            else:
                 return "%s{%s}" % (self.__class__.__name__, ", ".join("%s=%r" % (p, getattr(self, p)) for p in self.__props__))
         else:
             return super(Op, self).__str__()