[Jim -- some detail on tangled objectmanagers?]

A small step up from this is to replace the second list (a list of authors in a Book object) with a Catalog. The Book can determine all of it's authors by searching the index of 'book-list' properties.

With this change you never break data integrity by changing the list, although it is possible to break it by deleting a Book.

All you need to do is arrange for self.unindex_object to be called by self.manage_beforeDelete, I think. Oh, wierd! I just figured out why it's so hard to untangle the relationship between ObjectManagers and their children. The children are stored as attributes of the ObjectManager itself, NOT in a dict. This makes some sense from an acquisition point of view, but probably means that there are a whole bunch of "reserved ids" like manage_beforeDelete. Error Type: Bad Request Error Value: The id manage_beforeDelete is invalid - it is already in use. Yup! Can anyone tell me why Zope doesn't use __getattr__ to handle access to children of ObjectManagers and store the mapping to those children in a dictionary? That way we might have half a chance of preventing ZODB conflicts when adding multiple children simultaneously without losing the protection of ZODB conflicts when overlapping transactions try to modify the same attribute. Regards, Garth. -- <gtk@well.com>