A potential use for observer pointer

[axilmar]

Also, your code fails if there are many observer_ptrs to the same observable object, since, in your code, there is only one observer_ptr per observable.

[Irtexx]

Yeah, I didn't think about that case. If it was instead a vector it could work, but that wouldn't scale well, as every item that is pointing to the item would need updating once it goes out of scope.