312     try:

   312     try:

   313         return obj.target

   313         return obj.target

   314     except AttributeError:

   314     except AttributeError:

   315         return neg_role(obj.role)

   315         return neg_role(obj.role)

   316 

   316 

   320 

   317 

   321 class CubicWebEventManager(object):

   318 class CubicWebEventManager(object):

   322     """simple event / callback manager.

   319     """simple event / callback manager.

   323 

   320 

   324     Typical usage to register a callback::

   321     Typical usage to register a callback::