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Five Minute Design Patterns

Template Factory Singleton Iterator Adapter Façade Observer Command Strategy Decorator. Five Minute Design Patterns. Doug Marttila Forest and the Trees May 30, 2009. Design Patterns. WTF Not a framework 23 - not all applicable to Flash and Flex You’ve used them.

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Five Minute Design Patterns

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  1. Template Factory Singleton Iterator Adapter Façade Observer Command Strategy Decorator Five Minute Design Patterns • Doug Marttila • Forest and the Trees • May 30, 2009

  2. Design Patterns • WTF • Not a framework • 23 - not all applicable to Flash and Flex • You’ve used them

  3. Why Patterns Matter • Common language • CS is good for you • Speed up your development • Preexisting documentation • Refine your solutions • Explains the why

  4. Best Practices? • Not really in this presentation • Beware patterns overload

  5. Best Practices • Encapsulate what varies • Program to an interface (or super class) • Favor composition over inheritance • Inversion of Control • Hollywood principle

  6. Categories of Patterns(Are these useful at all? Not so much.) • Creational • Structural • Behavioral

  7. Template • Define the skeleton (or invariant parts) of an algorithm in a method, while deferring some steps to subclasses. • Setup the big picture and leave the details to the person doing the work.

  8. Factory • Define an interface for creating an object, but let the subclasses decide which class to instantiate. The Factory method lets a class defer instantiation to subclasses

  9. Singleton • Singleton Pattern ensures a class has only one instance, and provides a global point of access to it.

  10. Iterator • The Iterator Pattern provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation

  11. Adapter • The Adapter Pattern converts the interface of a class into another interface the clients expect. • Adapter lets classes work together that couldn'totherwise because of incompatible interfaces.

  12. Façade • The Façade Pattern provides a unified interface to a set of interfaces in a subsystem. Facade defines a higher level interface that makes the subsystem easier to use. • Principle of Least Knowledge - talk only to your immediate friends

  13. Observer • The Observer Pattern defines a one-to-many dependency between objects so that when one object changes state, all of its dependents are notified and updated automatically.

  14. Command • The Command Pattern encapsulates a request as an object, thereby letting you parameterize other objects with different requests, queue or log requests, and support undoable operations.

  15. Strategy • The Strategy Pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from the clients that use it.

  16. Decorator - last one! • The Decorator Pattern attaches additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.

  17. More Patterns!!! • State • Composite • Bridge • Proxy • Interpreter • Builder • Abstract Factory • Memento • Prototype • Visitor • Mediator • Chain of Responsibility • Flyweight • MVC

  18. Resources • Beerfug.com • http://www.forestandthetrees.com/designPatterns/ • Head First Design Patterns (the best) Java • GoF (dry, but what started it all) • ActionScript 3 with Design Patterns (Lott, Patterson) • ActionScript 3.0 Design Patterns (Sanders, Cumaranatunge)

  19. Thank You! • Doug Marttila • forestandthetrees.com • doug@forestandthetrees.com • beerfug.com • (first wednesday of every month, beer + code)

  20. FoT!

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