Dependency Inversion Principle

Dependency Inversion Principle — a practical guide to DIP SOLID with clear examples you can reuse in real projects.

OOP Tutorial Series (51/65). Prefer one article? Read the complete OOP tutorial.

Short description

DIP is the principle behind good dependency injection and testable architecture.

DIP

interface UserRepository { public function find(int $id): ?User; }
class UserService {
    public function __construct(private UserRepository $users) {}
}