All the solutions shown in this thread involving references are not general enough due to wrong assumptions, see FAQ in Object::ID.

Really ? ... *all* of them ?
I think the OP is concerned about determining whether 2 existent objects are the same, not whether a current object has the same "address" as an obsolete one.
So long as 2 reference addresses of currently existent objects are being compared, then I don't really see the relevance of the FAQ in Object::ID.

Cheers,
Rob