# Sometimes persistent classes are never meant to be persisted. The most
# common example are CMFCore directory views and filesystem objects.
# Register specific handlers that are no-ops to circumvent
from zope.interface import implements
from zope.app.keyreference.interfaces import IKeyReference, NotYet

def addIntIdSubscriber(ob, event):
    return

def removeIntIdSubscriber(ob, event):
    return

def moveIntIdSubscriber(ob, event):
    return

class KeyReferenceNever(object):
    """A keyreference that is never ready"""
    implements(IKeyReference)
    
    key_type_id = 'five.intid.cmfexceptions.keyreference'
    
    def __init__(self, obj):
        raise NotYet()
    
    def __call__(self):
        return None
        
    def __cmp__(self, other):
        if self.key_type_id == other.key_type_id:
            return cmp(self, other)
        return cmp(self.key_type_id, other.key_type_id)