Initially, when a developer sees the visitor design pattern, it seems that it can be easily replaced using polymorphism and can rely on the dynamic types of the classes. However, what if we have a huge type hierarchy? In such a case, every single change will have to change an interface as well, which will lead to changing a whole bunch of classes, and so on.
For our class diagram and example, let's imagine that we are writing a text editor and we have documents. We want to be able to save each document in at least two data formats, but new ones could come. The following diagram shows the class diagram for our application that uses the visitor design pattern:
As you can see in the preceding diagram, we have two seemingly ...
