Dependency Inversion Principle

Dependency Inversion Principle. This was presented during Software Engineering class in Bandung, April 2017.

Transcript

1. Dependency Inversion Principle @afnizarnur / @helmisatria / @knfalah / @miftahulawali Object Oriented Programming Design Principle April 17, 2017
2. Hello Dependency Inversion Principle April 17, 2017
3. What’s dependency? Dependency Inversion Principle April 17, 2017
4. and what’s inversion? Dependency Inversion Principle April 17, 2017
5. and again what’s principle? Dependency Inversion Principle April 17, 2017
6. Let’s hear the story Dependency Inversion Principle April 17, 2017
7. Dependency Inversion Principle April 17, 2017
8. So, Dependency Inversion Principle is… Dependency Inversion Principle April 17, 2017
9. Dependency Inversion Principle April 17, 2017 “High level objects should not depend on low level implementations”
10. Why using Dependency Inversion Principle? Dependency Inversion Principle April 17, 2017
11. Implement Dependency Inversion Principle and code example Dependency Inversion Principle April 17, 2017
12. Dependency Inversion Principle April 17, 2017 class PasswordReminder { private $dbConnection; public function __construct(MySQLConnection $dbConnection) { $this->dbConnection = $dbConnection; } }
13. Dependency Inversion Principle April 17, 2017 class PasswordReminder { private $dbConnection; public function __construct(MySQLConnection $dbConnection) { $this->dbConnection = $dbConnection; } } Low Level High Level
14. But that’s the bad example Dependency Inversion Principle April 17, 2017
15. “Depend on Abstraction not on concretions” Dependency Inversion Principle April 17, 2017
16. Dependency Inversion Principle April 17, 2017 class PasswordReminder { private $dbConnection; public function __construct(MySQLConnection $dbConnection) { $this->dbConnection = $dbConnection; } } Low Level High Level
17. PasswordReminder class is being forced to depend on the MySQLConnection class. Dependency Inversion Principle April 17, 2017
18. Your class should not care what class you’ll use ✌ Dependency Inversion Principle April 17, 2017
19. Dependency Inversion Principle April 17, 2017 interface DBConnectionInterface { public function connect(); }
20. The good example Dependency Inversion Principle April 17, 2017
21. Dependency Inversion Principle April 17, 2017 class MySQLConnection implements DBConnectionInterface { public function connect() { return "Database connection"; } } class PasswordReminder { private $dbConnection; public function __construct(DBConnectionInterface $dbConnection) { $this->dbConnection = $dbConnection; } }
22. “Depend on Abstraction not on concretions” Dependency Inversion Principle April 17, 2017
23. Conclusion Dependency Inversion Principle April 17, 2017
24. “Your code which can easily be extended, modified, tested, and refactored without any problems. ” Dependency Inversion Principle April 17, 2017
25. Thank you! Dependency Inversion Principle April 17, 2017