magic accessors to the rescue

1 files changed, 13 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index 3f9aef2b7..402e52272 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -1659,6 +1659,8 @@ class ClauseElement(Visitable):
     is_selectable = False
     is_clause_element = True
 
+    _order_by_label_element = None
+
     def _clone(self):
         """Create a shallow copy of this ClauseElement.
 
@@ -3690,6 +3692,13 @@ class UnaryExpression(ColumnElement):
         self.type = sqltypes.to_instance(type_)
         self.negate = negate
 
+    @util.memoized_property
+    def _order_by_label_element(self):
+        if self.modifier in (operators.desc_op, operators.asc_op):
+            return self.element._order_by_label_element
+        else:
+            return None
+
     @property
     def _from_objects(self):
         return self.element._from_objects
@@ -4327,6 +4336,10 @@ class Label(ColumnElement):
         self._proxies = [element]
 
     @util.memoized_property
+    def _order_by_label_element(self):
+        return self
+
+    @util.memoized_property
     def type(self):
         return sqltypes.to_instance(
                     self._type or getattr(self._element, 'type', None)