SE450: Creational Patterns: Prototype [8/12]

• Name -
• Intent - Specify the kinds of objects to create using a prototypical instance, and create new objects by copying the prototype
• Problem -
  • Classes are instantiated or specified at run time by dynamic loading
  • You want to avoid building a class heirarchy of factories that parallel the class heirarchy of products
  • When instances of a class can only have a few combinations of state.
• Solution - Create a prototypical instance, and copy it (or clone it) when you need new objects
• Participants and Collaborators
  • Prototype
  • ConcretePrototype (or just a Prototype)
  • Client
• Consequences
  • Hides the concrete product class - clients don't need to change as much
  • Need to be concerned about shallow vs. deep copy
  • Allows you to return the type you want, instead of Object like the clone method of Java
• Implementation
  • Use a prototype manager
  • Implement the "clone" operation
  • Initialize the "clone"
• GoF Reference (117)
• Example files are here