Chapter 23. The Command Pattern
The Chain of Responsibility forwards requests along a chain of classes, but the Command pattern forwards a request only to a specific object. It encloses a request for a specific action inside an object and gives it a known public interface. It lets you give the client the ability to make requests without knowing anything about the actual action that will be performed and allows you to change that action without affecting the client program in any way.
When you build a VB user interface, you provide menu items, buttons, check boxes, and so forth to allow the user to tell the program what to do. When a user selects one of these controls, the program receives a clicked event, which it receives into a special ...