Object-Oriented ActionScript 3.0
Peter Elst
4th-6th June 2008
Edinburgh, Scotland

Object-Oriented Programming
■ Difficult
■ Scary
■ Overhead
■ Only for large teams
4th-6th June 2008
Edinburgh, Scotland

Object-Oriented Programming
■ Difficult? Structured code
■ Scary
■ Overhead
■ Only for large teams
4th-6th June 2008
Edinburgh, Scotland

Object-Oriented Programming
■ Difficult? Structured code
■ Scary? Initial learning curve
■ Overhead
■ Only for large teams
4th-6th June 2008
Edinburgh, Scotland

Object-Oriented Programming
■ Difficult? Structured code
■ Scary? Initial learning curve
■ Overhead? Promotes code reuse
■ Only for large teams
4th-6th June 2008
Edinburgh, Scotland

Object-Oriented Programming
■ Difficult? Structured code
■ Scary? Initial learning curve
■ Overhead? Promotes code reuse
■ Only for large teams? Useful for anyone
4th-6th June 2008
Edinburgh, Scotland

Classes (the artist formerly known as prototype)
■ The way things were:
function Conference() {
this.name = \"Flashforward\";
}
Conference.prototype.getName = function() {
trace(\"conference name: \"+this.name);
}
var myConference = new Conference();
myConference.getName();
4th-6th June 2008
Edinburgh, Scotland

Classes (the artist formerly known as prototype)
■ The way things are:
package {
public class Conference {
public var name:String = \"Flashforward\";
public function getName():void {
trace(\"conference name: \"+this.name);
}
}
}
4th-6th June 2008
Edinburgh, Scotland

Instances
■ Classes provide a blueprint
■ Instances set their values for properties
4th-6th June 2008
Edinburgh, Scotland

Inheritance (getting rich the easy way)
■ Classes can extend each-other
■ Avoids code duplication
■ Properties and methods can be overridden
package {
public class SuperClass extends BaseClass {
public function SuperClass() {
super();
}
}
}
4th-6th June 2008
Edinburgh, Scotland

Inheritance vs composition
■ Inheritance deals with an is a relationship
■ Composition is used for has a relationships
Employee is a Person
Employee has a Job
4th-6th June 2008
Edinburgh, Scotland

Encapsulation (don't touch my stuff)
■ Protect the inner workings of your code
through the use of access modifiers
■ Provide an API for other classes to use by
providing getter/setter methods
public - anything can access this
private - only the class itself can access
protected - class and its subclasses can access
internal (default) - all classes in the same class package
4th-6th June 2008
Edinburgh, Scotland

Polymorphism (copycat behavior)
■ Have classes use the same method names
■ Allows classes to be swapped at runtime
■ Same name but different implementation
Doctor.work()
Fireman.work()
WebDeveloper.work()
4th-6th June 2008
Edinburgh, Scotland

Interfaces (sign on the dotted line)
■ Classes can use one or more interfaces
■ Interfaces require a class to implement a
specific set of methods
■ Used to formalize polymorphism
■ Interfaces can extend each-other
4th-6th June 2008
Edinburgh, Scotland

Design Patterns
General solutions to common problems
4th-6th June 2008
Edinburgh, Scotland

Observer pattern
■ Problem: notify other classes when an
update occurs in a data model
■ Solution: keep an array of all instances that
want to be notified and call their update
method then the model has changed
4th-6th June 2008
Edinburgh, Scotland

Singleton pattern
■ Problem: allow only one instance of a class
to exist in an application
■ Solution: prevent the constructor from being
called outside of the class scope and provide
a static method for returning the single class
instance
4th-6th June 2008
Edinburgh, Scotland

Want to learn more?
Books
■ Object-Oriented ActionScript 3.0
■ Essential ActionScript 3.0
Course
■ Core ActionScript 3.0 (Skills Matter - London)
4th-6th June 2008
Edinburgh, Scotland

Thanks!
4th-6th June 2008
Edinburgh, Scotland

Get in touch!
Peter Elst
Flash Platform Consultant
Blog: www.peterelst.com
Email: training@peterelst.com
LinkedIn: www.linkedin.com/in/peterelst
Twitter: www.twitter.com/peterelst
4th-6th June 2008
Edinburgh, Scotland