You can put a pointer to an object into a collection by using the virtual function insert():

This function inserts in the way most natural for the collection. Faced with a stack, it pushes an item onto the stack. Faced with a queue, it appends the item to the queue. In a sorted collection, it inserts the new item so that items before it compare less than itself, items after it compare greater than itself, and items equal compare equal, if duplicates are allowed. See the example in Smalltalk-like Classes Example for an example using insert().

You must always insert pointers to real objects. Since all RWCollection classes need to dereference their contents for some methods such as find(), inserting a zero will cause such methods to crash. If you must store an empty object, we suggest you create and insert a default constructed object of the appropriate type, such as RWCollectable*.