[Zope-dev] Lists of Objects

Hello, I am currently keeping a list of objects sorted in a particular object. I am wondering if anyone has an opinion about whether I should keep just the 'id' in this list or if it is ok to actually keep a reference to the object in the list. When I use the list at a later point in time I will need to access several attributes of the object. If I keep the 'id' I would have to find the object for each entry in the list. Thanks in advance for any opinions. -Jack Fitzgerald