The SOLID principles are a set of five principles that provide guidelines for writing maintainable and extensible object-oriented code. The principles were first introduced by Robert C. Martin (also known as “Uncle Bob”) and are widely adopted by software developers to write high-quality software.
Here are the five SOLID principles:
- Single Responsibility Principle (SRP): A class should have only one reason to change. This means that a class should have only one responsibility or job, and it should do that job well.
- Open-Closed Principle (OCP): A class should be open for extension but closed for modification. This means that we should be able to add new functionality to a class without changing its existing code.
- Liskov Substitution Principle (LSP): Subtypes must be substitutable for their base types. This means that any instance of a base class should be replaceable with an instance of a derived class without affecting the correctness of the program.
- Interface Segregation Principle (ISP): Clients should not be forced to depend on methods they do not use. This means that we should design interfaces that are specific to their intended use, and we should avoid creating “fat” interfaces that contain many methods.
- Dependency Inversion Principle (DIP): High-level modules should not depend on low-level modules. Both should depend on abstractions. Abstractions should not depend on details. Details should depend on abstractions. This means that we should depend on abstractions (interfaces or abstract classes) instead of concrete implementations, and we should avoid creating tight coupling between different parts of the system.
These principles help to ensure that our code is modular, flexible, and maintainable. By following these principles, we can write code that is easier to test, refactor, and extend. Applying SOLID principles in our code can result in code that is easier to maintain, has fewer bugs, and is more robust.