Design Patterns Summer Course 2009-2010 - Session#3
- 1. Let’s break the ice….Lecture # 3Ahmed SafwatMuhamadHeshamAbdelrahman Al-Ogail
- 2. AgendaYou 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 ourselvesHow do we ensure that a class has only one instance and that the instance is easily accessible?UniqueGlobal Access
- 6. SingletonFormalThe Singleton assures that there is one and only one instance of a class, and provides a global point of access to itMake sure that there can be one and only one instance of a class
- 7. Singleton
- 8. Our Current StatusWhat have we did till now?
- 9. Call for New RequirementEach level can be in one of two styles:PharonicAztecFirst level is Aztec.Second and third level is Pharonic.
- 10. First Try Implementation1. We need find where we decide which image we load.2. Categorize images to 2 sets, Pharonic an Aztec.
- 11. Our Code Smells BadEach time we add a new theme we add piles of if-elsestatements.Our class do more than its job (SCSR).
- 14. My Restaurant DrinksWater BottleCoke softOrange softLemon soft
- 15. Who’s our hero?So, what we can call it?
- 16. Let’s Google it!
- 17. Break
- 19. Meet Abstract FactoryLemon softCoke soft
- 20. Second Try for ImplementationJust Code It
- 21. Common Uses
- 22. What’s Next?Consequences of Factory Pattern.Factory Method Pattern.Implement Factory Pattern using Prototype Pattern.