diff -r d6fd82a5a4e8 -r a63d7886fcf5 appobject.py
--- a/appobject.py	Tue Mar 30 14:32:03 2010 +0200
+++ b/appobject.py	Wed Mar 31 15:39:09 2010 +0200
@@ -14,6 +14,7 @@
 from warnings import warn
 
 from logilab.common.deprecation import deprecated
+from logilab.common.decorators import classproperty
 from logilab.common.logging_ext import set_log_methods
 
 
@@ -245,6 +246,12 @@
     __regid__ = None
     __select__ = yes()
 
+    @classproperty
+    def __registries__(cls):
+        if cls.__registry__ is None:
+            return ()
+        return (cls.__registry__,)
+
     @classmethod
     def __registered__(cls, registry):
         """called by the registry when the appobject has been registered.