Chapter 29. The Facade Pattern
In the previous chapter, we covered a third structural pattern, the bridge pattern, which helps to define an abstraction and its implementation in a decoupled way, so that both can vary independently.
As systems evolve, they can get very complex. It is not unusual to end up with a very large (and sometimes confusing) collection of classes and interactions. In many cases, we don't want to expose this complexity to the client. This is where our next structural pattern comes to the rescue: facade.
The facade design pattern helps us to hide the internal complexity of our systems and expose only what is necessary to the client through a simplified interface. In essence, facade is an abstraction layer implemented over an existing complex system.
Let's take the example of the computer to illustrate things. A computer is a complex machine that depends on several parts to be fully functional. To keep things simple, the word "computer", in this case, refers to an IBM derivative...
