Facade

Facade is a structural design pattern that provides a simplified interface to a library, a framework, or any other complex set of classes.

A facade is a class that provides a simple interface to a complex subsystem which contains lots of moving parts. A facade might provide limited functionality in comparison to working with the subsystem directly. However, it includes only those features that clients really care about.

Problem

Imagine that you must make your code work with a broad set of objects that belong to a sophisticated library or framework. Ordinarily, you’d need to initialize all of those objects, keep track of dependencies, execute methods in the correct order, and so on.

As a result, the business logic of your classes would become tightly coupled to the implementation details of 3rd-party classes, making it hard to comprehend and maintain.

When to use

• Use the Facade pattern when you need to have a limited but straightforward interface to a complex subsystem.

• Use the Facade when you want to structure a subsystem into layers.

Pros

• You can isolate your code from the complexity of a subsystem.

Cons

• A facade can become a god object coupled to all classes of an app.