Introducing the Command pattern
As we saw in the previous chapter, Behavioral patterns focus on the responsibilities that an object has. It deals with the interaction among objects to achieve larger functionality. The Command pattern is a behavioral design pattern in which an object is used to encapsulate all the information needed to perform an action or trigger an event at a later time. This information includes the following:
The method name
An object that owns the method
Values for method parameters
Let's understand the pattern with a very simple software example. Consider the case of an installation wizard. A typical wizard may contain multiple phases or screens that capture a user's preferences. While the user browses through the wizard, s/he makes certain choices. Wizards are typically implemented with the Command pattern. A wizard is first launched with an object called the Command object. The preferences or choices made by the user in multiple phases of the wizard are then stored in...
