1. Let’s break the ice…. Lecture # 3 Ahmed Safwat MuhamadHesham Abdelrahman Al-Ogail

2. Agenda You can solve it yourself! Meet Singleton pattern. Call for a new requirement. First try for implementation. Bad smell code. Who’s our hero?

3. Agenda (con’t) Meet today’s pattern. Break!! Second try for implementation. Common uses. What’s next?

4. What’s a design pattern? A design pattern is: Set of class(es). Interact together. In UML (class diagram). Informal

5. Let’s solve it ourselves How do we ensure that a class has only one instance and that the instance is easily accessible? Unique Global Access

6. Singleton Formal The Singleton assures that there is one and only one instance of a class, and provides a global point of access to it Make sure that there can be one and only one instance of a class

7. Singleton

8. Our Current Status What have we did till now?

9. Call for New Requirement Each level can be in one of two styles: Pharonic Aztec First level is Aztec. Second and third level is Pharonic.

10. First Try Implementation 1. We need find where we decide which image we load. 2. Categorize images to 2 sets, Pharonic an Aztec.

11. Our Code Smells Bad Each time we add a new theme we add piles of if-elsestatements. Our class do more than its job (SCSR).

12. My Restaurant Drinks

13. My Restaurant Drinks

14. My Restaurant Drinks Water Bottle Coke soft Orange soft Lemon soft

15. Who’s our hero? So, what we can call it?

16. Let’s Google it!

17. Break

18. Meet Abstract Factory

19. Meet Abstract Factory Lemon soft Coke soft

20. Second Try for Implementation Just Code It

21. Common Uses

22. What’s Next? Consequences of Factory Pattern. Factory Method Pattern. Implement Factory Pattern using Prototype Pattern.

23. Thank you ... Questions?? ahmedaliyossef@acm.org mhesham.fcis@gmail.com zikas_zak@hotmail.com