Open/Closed Principle

This principle states that “Software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification” which means you should be able to extend a class behavior, without modifying it.

Let’s understand Open/Closed Principle using an example:

Imagine you have a class called PaymentProcessor that processes payments for an online store. Initially, the PaymentProcessor class only supports processing payments using credit cards. However, you want to extend its functionality to also support processing payments using PayPal.

Instead of modifying the existing PaymentProcessor class to add PayPal support, you can create a new class called PayPalPaymentProcessor that extends the PaymentProcessor class. This way, the PaymentProcessor class remains closed for modification but open for extension, adhering to the Open-Closed Principle

In software development, Object-Oriented Design plays a crucial role when it comes to writing flexible, scalable, maintainable, and reusable code. There are so many benefits of using OOD but every developer should also know the SOLID principle for good object-oriented design in programming. The SOLID principle was introduced by Robert C. Martin, also known as Uncle Bob and it is a coding standard in programming. This principle is an acronym of the five principles which are given below:

• Single Responsibility Principle (SRP)
• Open/Closed Principle
• Liskov’s Substitution Principle (LSP)
• Interface Segregation Principle (ISP)
• Dependency Inversion Principle (DIP)

The SOLID principle helps in reducing tight coupling. Tight coupling means a group of classes are highly dependent on one another which you should avoid in your code.

• Opposite of tight coupling is loose coupling and your code is considered as a good code when it has loosely-coupled classes.
• Loosely coupled classes minimize changes in your code, helps in making code more reusable, maintainable, flexible and stable. Now let’s discuss one by one these principles…