SOLID++: More Object-Oriented Design Principles
Introduction
If you’ve been writing object-oriented code for a while, you’ve probably heard of the SOLID principles. These five guidelines have become so fundamental to OO design that they’re often treated as the complete playbook for writing good code. But here’s the thing - they’re just the beginning.
Beyond SOLID
The SOLID principles, introduced by Robert C. Martin (affectionately known as “Uncle Bob”) in the early 2000s, are like the foundation of a well-built house. They give us a stable base for creating code that’s easier to maintain, extend, and understand. You can find a good explanation of them in this post at freeCodeCamp. Briefly, the SOLID principles are:
Single Responsibility Principle - A class should do one thing, and do it well
Open/Closed Principle - Open for extension, closed for modification
Liskov Substitution Principle - Subtypes must be substitutable for their base types
Interface Segregation Principle - Clients should not be forced to depend on interfaces they do not use
Dependency Inversion Principle - High-level modules should not depend on low-level modules; both should depend on abstractions
While SOLID principles are fantastic tools for good design, they’re part of a larger toolbox. There are several other powerful OOD principles that can take your code to the next level. In this series, we’ll explore three of my favorites:
- Composition Over Inheritance - Learn when to favor object composition over class inheritance
- Law of Demeter - Discover how to write code that minds its own business
- Encapsulate What Varies - Master the art of isolating change
While SOLID principles provide an excellent foundation for object-oriented design, they’re just the beginning of your journey toward writing exceptional code. In the upcoming posts, we’ll explore these additional principles through practical examples and real-world scenarios. By the end of this series, you’ll have new tools to help you write code that’s not just solid - it’s outstanding.
Conclusion
Stay tuned for our next post, where we’ll dive into Composition Over Inheritance and learn why sometimes it’s better to have a friend than a complex relationship with parents!
- Cover image designed by pikisuperstar / Freepik