Stage 5 · Lesson 10 of 10
SOLID as review questions
is five design principles for code, the kind built from classes. : a class should have one reason to change. Open/closed: add new behaviour without editing code that already works.
Liskov substitution: a subclass must work anywhere its parent class does. Interface segregation: prefer small, focused interfaces over one big one. inversion: depend on abstractions (a general contract, not a specific class), so you can pass in a fake version during tests.
They are most useful as questions to ask when a class is getting hard to change, not as rules for a first draft. Applied everywhere in a small program, they produce layers of interfaces with one implementation each. That is harder to read than the code they replaced.
A question to check yourself, an AI practice session and 1 cheat sheet entry come when you add the roadmap to your account. Add it
Resources for this stage
Start with· follow one of these
- CoursePaidGrokking SOLID Design Principles
Design Gurus · Beginner · $50 one-time
Five principles with code examples, including when applying them makes code worse
- GuideFreeRefactoring.Guru: Code Smells and Refactoring
Refactoring.Guru · Beginner
Free catalogue of code smells and the small refactorings that fix each one