Command Pattern

Command Pattern Intent Also known as “Action” or “Transaction” Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests,and support undoable operations. Also known as “Action” or “Transaction” Motivating example GUI button or menuitem, when clicked, do some action. The button or menuitem (the invoker) do not have to know what actions are being carried out and by whom (the receiver)

(Imperfect) Diner Analogy Customer (client); Order (command); Waitress (invoker); Cook (receiver);

Home Automation Remote Example

Ventor Supplied Classes

Command Object

Command Pattern Defined

Command Pattern Class Diagram

Implement Remote Control

Support Undo

Undo with State

MacroCommand

Use Case: Queuing Requests

Use Case: Logging Requests