The document discusses several design patterns including Singleton, Observer, Command, Proxy, Facade, Adapter, and Mediator patterns. It provides descriptions of what each pattern is, including examples of how and when to use each pattern. It also discusses the Model-View-Controller pattern and how it is a collection of patterns used to structure user interface applications.

2. Quick Overview You’re going to learn about a number of design patterns. You’re going to work out some of them in code. You’re going to apply most of the patterns we learn today towards an example Model View Controller application

3. Design Patterns… Are reusable solutions to common design problems Improve the development workflow Help teams to work together efficiently Help you deal with change

4. Design Patterns… are not Algorithms are not Architectural Patterns are not finished designs are not written in stone

5. Singleton Pattern The one and only

6. The Singleton Pattern… has only ONE instance ever is created only when needed assures that every object in an application is using the same resource (global access point)

7. Singleton Pattern Lab We’re going to implement an Asset Manager. Application Asset Manager Images Sound

8. Singleton Pattern Tips Use this pattern when you need one and only one instance of a class The package mx.managers are all singletons DragManager CursorManager HistoryManager FocusManager etc…

9. Command Pattern Execute Here 

10. The Command Pattern… encapsulates method invocation. is a class used to carry out an ‘order’ authenticate user process form sit on cat often encapsulates an algorithm. often performs tricky operations.

11. The Command Pattern… Separating functionality into command classes makes it straight forward to implement complex operations. Undo and Redo Queue or Pipeline Deferred and transactional execution

12. Command Pattern Lab Create Several Commands that encapsulate visual manipulations of your choice (rotate, scale, swap display list location etc). User gestures will execute these commands.

13. Observer Pattern

14. The Observer Pattern… defines a one to many relationship between objects so when one object changes, all the observers are notified. is also known as Publish/Subscribe, and Listener. is used in event driven design. reduces coupling between classes, but they can still interact.

15. Observer Pattern Lab Event Dispatcher Observer Observer Observer In this lab, we’re going to leverage the Observer Pattern implementation built into the Flash Player.

16. Proxy Pattern May I Help You?

17. A Proxy… stands in for and provides access to another object. can control or guard access can be used to manage instantiation

18. The Virtual Proxy The Virtual Proxy stands in for an object that is expensive to create is not immediately available The Loader class is a Virtual Proxy. DisplayObjectContainer Loader Sprite Stage MovieClip

19. The Remote Proxy The Remote Proxy stands in for a remote object and, delegates requests to a remote object manages communication with remote object Image Search Flickr API Remote PhotoProxy Remote Service Your Application

20. Proxy Pattern Lab In this lab, we’re going to implement a remote proxy and learn about a time saving technique. Image Search Flickr API Remote PhotoProxy Remote Service Your Application

21. Façade Pattern Hiding Complexity

22. Façade Pattern… The Façade pattern simplifies access to a collection of objects. Often implemented as a singleton (only need one) Hides the complexity of underlying objects Application Facade Model View Controller

23. Adapter Pattern a.k.a. Wrapper

24. Adapter Pattern… The Adapter pattern converts and translates the API of one object to the API of another object. often applied when reusing legacy code providing a common API to several 3 rd party libraries or algorithms Music Player MP3 Adapter FLAC Adapter AC3 Adapter FLAC Decoder MP3 Decoder WAV Decoder

25. Mediator Pattern Central Communication

26. Mediator Pattern The Mediator Pattern is used to centralize complex communication and control between related objects. Application Username Textbox Password Textbox Submit Button New Account Form Account Form Mediator

27. Model View Controller A collection of patterns

28. Model View Controller (MVC) The MVC Pattern is a collection of patterns used to address the challenges presented by rich user interfaces.

29. Model View Controller (MVC) MVC brings order to applications and application development by, decoupling the user interface of an application from the data model and business logic. allow each of the elements to be changed without impacting the other. promotes reusability between UI components and data objects.

30. Quick Comparison Model View Controller Command Façade Proxy Mediator Observer Notification Model View Controller Command Delegate Service CairngormEvent Cairngorm

31. What I Like About PureMVC Platform & language independent mobile, server, browser, desktop AS2, AS3, ColdFusion, C#, Java, Perl, PHP, Python, more Excellent Documentation and Active Community Programmed to Interfaces Winner at SilvaFUG between 9 frameworks Cairngorm

32. PureMVC Conceptual Diagram

33. PureMVC - Model

34. PureMVC - View

35. PureMVC - Controller

36. PureMVC - Notifications

37. Good Practice Interfaces Design Approach Further Reading

38. Interfaces There are (hidden) two layers to every class you write Interface Implementation

39. Designing Applications

40. Recommended Reading O’Reilly Head First Design Patterns