Project 1 - Phase 2

Visitor Pattern

• Visitor Pattern
  • There is an interface "Visitor" which contains methods for each class in the hierarchy.
  • Each class in a hierarchy implements an interface "Visitable" that contains a single method "accept", which takes a single Visitor as a parameter. This method simply calls the proper method in the Visitor.
  • The visitor hierarchy sacrifices the ability to add new classes to a hierarchy for the ability to add new methods.
• Diagram
• Why is it useful here?
  • Because of our inheritance scheme, there is a need for virtual methods. While this could be done by modifying the generated code, this is a bad idea.
  • The sacrifice of a dynamic hierarchy for new methods is not a big deal because the hierarchy can be re-generated to add new functionality.