Visitor Design Pattern Examples

C++ example

Let’s look at an example where we have a base class of File, which is implemented by three classes named ArchivedFile, SplitFile, and ExtractedFile. Let’s assume that we want to apply an operation Dispatch to all the files without affecting the object’s structure. Adding this method to the File class hierarchy doesn’t sound like a good idea because Dispatch doesn’t really belong in that object structure.

We’ll create a visitor class called AbstracttDispatcher and a concrete visitor class called Dispatcher. Depending on the object type, it will add an operation to the file objects. Let’s look at its code.