Bridge Design Pattern

The Bridge Design Pattern is a structural design pattern that decouples an abstraction from its implementation so that the two can vary independently. This pattern is useful when you want to separate the abstract interface from its concrete implementation, allowing you to change one without affecting the other.

In simpler terms, the Bridge Design Pattern allows you to create a hierarchy of abstractions and a hierarchy of implementations, and then connect them together in a flexible way. This makes your code more modular and easier to understand, change, and test.

key points of the Bridge Design Pattern:

1. Intent:

   • The main intent of the Bridge pattern is to decouple an abstraction from its implementation so that both can vary independently. It provides a way to separate abstraction and implementation into two separate hierarchies.

2. Key Components:

   • Abstraction:
     • Declares the abstraction's interface and maintains a reference to an object of type Implementor.
   • Refined Abstraction:
     • Extends the interface defined by Abstraction. It can add additional functionality or customization.
   • Implementor:
     • Declares the interface for the implementation classes. It does not need to match the Abstraction interface. It provides a different perspective on the abstraction.
   • Concrete Implementor:
     • Implements the Implementor interface. There can be multiple Concrete Implementors with different implementations.

3. Decoupling Abstraction and Implementation:

   • The Bridge pattern separates the abstraction from its implementation by providing an interface in the abstraction and an interface in the implementation, decoupling them from each other.

4. Flexibility and Extensibility:

   • The Bridge pattern allows the abstraction and implementation to evolve independently. You can introduce new abstractions or implementations without modifying existing code.

5. Composition over Inheritance:

   • The Bridge pattern promotes composition over inheritance. Instead of using a single class hierarchy to define different implementations, it uses composition to combine different abstractions and implementations.

6. Advantages:

   • Decoupling: The pattern decouples abstraction and implementation, allowing them to vary independently.
   • Flexibility: It provides flexibility in choosing different implementations for an abstraction.
   • Extensibility: It allows for the addition of new abstractions or implementations without modifying existing code.

7. Use Cases:

   • The Bridge pattern is useful when you want to avoid a permanent binding between an abstraction and its implementation.
   • It is applicable when changes in the abstraction or implementation should not affect each other.

Example:

• Consider a drawing application where you have different shapes (abstraction) that can be rendered using different rendering techniques (implementation). The Bridge pattern could be used to allow shapes and rendering techniques to vary independently.