Dependency Inversion Principle

1. What Is the Dependency Inversion Principle?

High-level modules should not depend on low-level modules.

Program to interfaces, not implementations.

2. Why Is the Dependency Inversion Principle Needed?

Improve extensibility.

3. Implementing the Dependency Inversion Principle

Each class should provide an interface or abstract class whenever possible, or both.

The declared type of a variable should be an interface or abstract class whenever possible.

No class should derive from a concrete class; it should derive from an abstract class.

When using inheritance, follow the Liskov substitution principle whenever possible.

4. References

• Dependency Inversion Principle — Object-Oriented Design Principles