OO Design

SOLID Principles

• The SOLID Principles are five principles of Object-Oriented class design. These principles developers create and maintain a codebase that is strong but flexible to grow and change with minimal difficulty.

• The SOLID Principles are:

  1. S : Single-responsiblity Principle.

  2. O : Open-closed Principle.

  3. L : Liskov Substitution Principle.

  4. I : Interface Segregation Principle.

  5. D : Dependency Inversion Principle.

The Single Responsibility Principle (SRP)

• A class should have one, and only one, reason to change that means the class should have only one job.

The Open Closed Principle (OCP)

• We should be able to extend a classes behavior, without modifying.

The Liskov Substitution Principle (LSP)

• Derived classes must be substitutable for their base classes. That means when we create a new derived class from a base class we should not have to modify code to work this derived class.

The Interface Segregation Principle (ISP)

• Clients should not be forced to depend upon interfaces that they do not use. This is all about building multiple interfaces that will provide only the methods that a client needs. Simple put it’s better to have two smaller interfaces than one large fat interface.

The Dependency Inversion Principle (DIP)

• Depend on abstraction, not on concretions. That means our class should depends on interfaces or acstract class insted of concretions classes and functions.