- the compiler extension now allows @compiles decorators

on base classes that extend to child classes, @compiles
decorators on child classes that aren't broken by a
@compiles decorator on the base class.

1 files changed, 11 insertions, 10 deletions

diff --git a/lib/sqlalchemy/sql/visitors.py b/lib/sqlalchemy/sql/visitors.py
index 4a54375f8..799486c02 100644
--- a/lib/sqlalchemy/sql/visitors.py
+++ b/lib/sqlalchemy/sql/visitors.py
@@ -40,16 +40,17 @@ class VisitableType(type):
         
         # set up an optimized visit dispatch function
         # for use by the compiler
-        visit_name = cls.__visit_name__
-        if isinstance(visit_name, str):
-            getter = operator.attrgetter("visit_%s" % visit_name)
-            def _compiler_dispatch(self, visitor, **kw):
-                return getter(visitor)(self, **kw)
-        else:
-            def _compiler_dispatch(self, visitor, **kw):
-                return getattr(visitor, 'visit_%s' % self.__visit_name__)(self, **kw)
-    
-        cls._compiler_dispatch = _compiler_dispatch
+        if '__visit_name__' in cls.__dict__:
+            visit_name = cls.__visit_name__
+            if isinstance(visit_name, str):
+                getter = operator.attrgetter("visit_%s" % visit_name)
+                def _compiler_dispatch(self, visitor, **kw):
+                    return getter(visitor)(self, **kw)
+            else:
+                def _compiler_dispatch(self, visitor, **kw):
+                    return getattr(visitor, 'visit_%s' % self.__visit_name__)(self, **kw)
+
+            cls._compiler_dispatch = _compiler_dispatch
         
         super(VisitableType, cls).__init__(clsname, bases, clsdict)