C SC 225 Lecture 9: Design Patterns: Model-View-Controller

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Design Patterns: Model-View-Controller

A Compound Pattern

• Model-View-Controller is not strictly speaking a design pattern
• It is not in the GoF pattern list
• Head First calls it a "compound pattern"
• Maybe better described as a software architecture
• The model is the application logic and is completely independent of user interaction
• The view is the visual representation (GUI) of the model and is completely independent of the application logic
• The controller is responsible for translating user input into actions on the model.
• It encompasses several patterns:
  • Observer : The view and possibly controller observe the model
  • Strategy : The controller is the strategy for the model
  • Composite : The view is a composite of GUI components
• An application structured in this way is very flexible, different views and controllers can be applied without changing each other or the model. "Encapsulate that which changes."