Generic Programming with Inheritance and Templates

• Design Patterns further recommends using an abstract base class for the iterator and the aggregate
• Generic code can then be written:

  void print_all(AbstractAggregate* items)
  {
     AbstractIterator* iter = items->create_iterator();
     while (!iter->is_done())
     {
        cout << iter->current_item() << "\n";
        iter->next();
     }
  }