add instance attribute ref to __slots__ in eventref -- bug 2210

svn: r10816

src/gen/lib/eventref.py

@@ -49,12 +49,13 @@ class EventRef(SecondaryObject, PrivacyBase, NoteBase, AttributeBase, RefBase):
     to the refereneced event.
     """
 
-    __slots__=('__role')
+    __slots__=('__role','ref')
 
     def __getstate__(self):
-        return{'__role': self.__role}
+        return{'__role': self.__role,'ref': self.ref}
     def __setstate__(self,dict_):
         self.__role = dict_['__role']
+        self.ref = dict_['ref']
 
     def __init__(self, source=None):
         """