A reference-based collection can be very efficient because pointers are small and inexpensive to manipulate. However, with a reference-based collection, you must always remember that you are responsible for memory management: the creation, maintenance, and destruction of the actual objects themselves. If you create two pointers to the same object and prematurely delete the object, you'll leave the second pointer pointing into nonsense. By the same token, you must never insert a nil pointer into a reference-based collection, since the collection has methods which must dereference its contained values.

Despite the added responsibility, don't avoid reference-based collections when you need them. The Essential Tools Module classes have member functions to help you, and in most cases, the ownership of the contained objects is obvious anyway. You should choose a reference-based collection if you need performance and size advantages: here the size of all pointers is the same, allowing a large degree of code reuse. Also choose the reference-based collection if you just want to point to an object rather than contain it (a set of selected objects in a dialog list, for example). Finally, for certain heterogeneous collections, the reference-based approach may be the only one viable.