Notes - Imperative Programming TT23, Design patterns

Created: June 14, 2023

Patterns

Adapter

Give the sales pitch for the “Adapter” design pattern.
  • Name: Adapter
  • Problem: You want to use an existing type, but it doesn’t impleemnt the required interface.
  • Solution:
    • Target: Interface we wish to provide
    • Client: The code that expects the required interface
    • Adaptee: The type we wish to present in a different interface
    • Adapter: The “wrapped” type, with the required adapter

Observer

Give the sales pitch for the “Observer” design pattern.
  • Name: Observer
  • Problem: You have a many-to-one relationship and want to reduce tight coupling
  • Solution:
    • Observer: Interface with a method to be notified when changes occur
    • Subject: A class for recording observers and notifying them of changes
    • Concrete Subject: A class that the observers are interested in and that notifies observers as required
    • Concrete Observer: A concrete implementation of the observer, which update when they are notified.

Model-View-Controller

Describe the three aspects of the model-view-controller pattern.
  • The model: The internal description of the data relevant to the application.
  • The view: The code responsible for presentation of data to users.
  • The controller: Processes user input, and updates the model as needed.


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