Decorator Pattern Lecture Oo29 Artificial Life Simulation

Teaching Points n Decorator Pattern n Artificial Life Simulation –Lab 3

Review n What is a component n How can you use components and interfaces to efficiently partition your system’s physical architecture? n In Java-style exception handling what is “thrown?”

Decorator Pattern n The Problem –sometimes we want to add responsibilities to individual objects, not to an entire class. –for responsibilities that can be add/withdrawn dynamically –when extension by subclassing is impractical

Decorator Pattern n The solution –Attach additional responsibilities to an object dynamically. –A flexible approach is to enclose the component in another object that adds the responsibility.

Decorator Pattern (structure)

Decorator Pattern (example)

Artificial Life Simulator n A framework n Pattern based –Decorator –Chain of responsibility –Observer –Iterator

Use Case Diagram

Architecture

Run Simulation Use Case

Update Creature State Use Case –Interaction with the world

Update Creature State Use Case n Reproduction

Teaching Points n Decorator Pattern n Artificial Life Simulation –Lab 3