SOLID in software development

SOLID is an acronym for five key design principles that promote the creation of well-structured, maintainable, and flexible object-oriented software. These principles were introduced by Robert C. Martin (Uncle Bob) and have become widely adopted by developers.

Let’s delve into each principle:

1. Single Responsibility Principle (SRP): This principle states that a class should have one, and only one, reason to change. In simpler terms, a class should focus on a single functionality or responsibility. This promotes modularity and reduces the risk of unintended consequences when modifying the class.

2. Open/Closed Principle (OCP): The OCP emphasises that software entities (classes, modules) should be open for extension but closed for modification. This means you should be able to extend the functionality of a class without altering its existing code. This is often achieved through inheritance and abstract classes.

3. Liskov Substitution Principle (LSP): This principle ensures that objects of a superclass can be replaced with objects of its subclasses without affecting the program’s correctness. In simpler terms, subclasses should be functionally interchangeable with their parent class. This promotes code reusability and reliability.

4. Interface Segregation Principle (ISP): The ISP suggests that clients shouldn’t be forced to depend on methods they don’t use. Large interfaces with a mix of unrelated functionalities can be cumbersome. This principle recommends splitting interfaces into smaller, more specific ones that cater to distinct client needs.

5. Dependency Inversion Principle (DIP): This principle advocates for depending on abstractions (interfaces) rather than concrete implementations. High-level modules should not rely on low-level modules directly. Instead, both should depend on a common abstraction. This allows for loose coupling and easier maintenance as concrete implementations can be changed without affecting the higher-level modules.

By following these SOLID principles, developers can create software that is:

• Easier to understand and maintain
• More flexible and adaptable to change
• Less prone to errors and bugs
• More reusable and extensible