Visiting complex objects

In the last section, we saw how the Visitor pattern allows us to add new operations to the existing hierarchy. In one of the examples, we visited a complex object that contained pointers to other objects. The visitor iterated over these pointers, in a limited way. We are now going to consider the general problem of visiting objects that are composed of other objects, or objects that contain other objects and build up to the demonstration of a working serialization/deserialization solution at the end.

Visiting composite objects

The general idea of visiting complex objects is quite straightforward - when visiting the object itself, we generally do not know all the details of how to handle each component or contained object. But there is something else that does - the visitor for that object type is written specifically to handle that class and nothing else. This observation suggests that the correct way to handle the component objects is to simply visit...