CS 210

1. CS 210 Introduction to Design Patterns September 26th, 2006

2. Head First Design Patterns Chapter 6 Command Pattern Encapsulating Invocation

3. Motivating problem description • Build a remote that will control variety of home devices • Sample devices: lights, stereo, TV, ceiling light, thermostat, sprinkler, hot tub, garden light, ceiling fan, garage door

4. Order orderUp takeOrder Make Burger & Shake Introducing the command pattern – Diner example createOder() Burger & Shake Order Slip Customer takeOder() Waiter orderUp() Command Cook make_X()

5. execute() execute() Create Command Object setCommand action1 action2 Introducing the command pattern creatCommandObject() Command Client setCommand() Invoker execute() Command Receiver action_X()

6. action() Receiver RemoteSlot execute() execute() execute() LightOnCommand GarageDoorOpen StereoOff Command Pattern for home automation An encapsulated Request execute(){ receiver.action() } Invoker Command

7. Simple Remote Control • Eclipse example

8. Command Pattern defined The Command Pattern encapsulates a request as an object, thereby letting you parameterize other objects with different requests, queue or log requests, and support undoable operations.

9. Client Invoker Receiver <<Interface>> Command setCommand() action() execute() undo() Command Pattern Class Diagram ConcreteCommand execute() undo()

10. Light <<Interface>> Command execute() undo() LightOnCommand LightOffCommand execute() undo() execute() undo() Command Pattern Class Diagram for Home automation RemoteControl RemoteLoader onCommands offCommands setCommand() onButtonPushed() offButtonPushed() on() off()