Software Design Principles Explained
1. Single Responsibility Principle (SRP)
The Single Responsibility Principle (SRP) states that a class should have only one reason to change, meaning it should have only one job or responsibility. This principle helps in creating more maintainable and understandable code by ensuring that each class has a specific and focused purpose.
Example: Consider a class that manages both the user interface and the database operations for a user management system. According to SRP, this class should be split into two separate classes: one responsible for the user interface and another for the database operations. This separation ensures that changes to the user interface do not affect the database logic and vice versa.
2. Open/Closed Principle (OCP)
The Open/Closed Principle (OCP) states that software entities (such as classes, modules, and functions) should be open for extension but closed for modification. This principle encourages the use of abstraction and inheritance to allow new functionality to be added without changing existing code.
Example: Imagine a payment processing system that initially supports only credit card payments. To add support for PayPal payments, you could create an abstract Payment class with a processPayment() method. Concrete classes like CreditCardPayment and PayPalPayment can extend this abstract class and implement the processPayment() method differently. This way, the core payment processing logic remains unchanged, and new payment methods can be added by extending the existing classes.