Hi, Thanks for that answer (this goes to Assaph too, of course). Robert Klemme wrote: > > If there are no special requirements for your object ids I suggest to use > Object#id and ObjectSpace#_id2ref: I'll add that to my notes and think about it. > You could better use a Set here. That saves you the inefficient check > (with an Array this is O(n) where n is the number of oids stored so far; > with a Set (hash internally) it's ~ O(1)). Thanks for the tip - I'm currently still in the second of the three phases (Make it run, make it right, make it fast)... :-) > I'd go for add_ref1 - although you should uncover a bit more of the > problem you are solving. Yes, in the meantime I've come to that conclusion, too. Having worked for an object-oriented database vendor some time ago, things like traversing object networks, persistence and similar themes come to my mind now and then... Happy rubying Stephan