Prevent theano.dot from catching all exceptions

theano/__init__.py

@@ -172,28 +172,26 @@ else:
 np.seterr(all=_all, divide=_divide, over=_over, under=_under, invalid=_invalid)
 del _all, _divide, _over, _under, _invalid
 
-# This is defined here because it is designed to work across symbolic
-#   datatypes (Sparse and Tensor)
-
 
 def dot(l, r):
-    """Return a symbolic matrix/dot product between l and r """
-    rval = NotImplemented
-    e0, e1 = None, None
+    """Return a symbolic dot product.
 
-    if rval == NotImplemented and hasattr(l, "__dot__"):
-        try:
-            rval = l.__dot__(r)
-        except Exception as e0:
-            rval = NotImplemented
-    if rval == NotImplemented and hasattr(r, "__rdot__"):
+    This is designed to work with both sparse and dense tensors types.
+    """
     try:
-            rval = r.__rdot__(l)
-        except Exception as e1:
-            rval = NotImplemented
-    if rval == NotImplemented:
-        raise NotImplementedError("Dot failed for the following reasons:", (e0, e1))
-    return rval
+        res = l.__dot__(r)
+
+        if res is NotImplemented:
+            raise NotImplementedError()
+
+        return res
+    except (NotImplementedError, AttributeError, TypeError):
+        res = r.__rdot__(l)
+
+        if res is NotImplemented:
+            raise NotImplementedError()
+
+        return res
 
 
 def get_scalar_constant_value(v):