Extends to built in class--! why we do so

[anurag]

Quite often in our class we write
public class MyClass extends Sprite
public class MyClass extends XMLDocument
public class MyClass extends URLLoader
etc
How does it works in get executed in our program.Basically I know extending class denotes inheritance also we can use and call fields/variables and methods
of that class from subclass.But extending built in class .Does it means the same
Than how to implement functions of built in class from subclass.
can anybody help please .Thanks in advance
With Regards
Anurag

[panel]

I don't really understand what d oyou mean by 'implement'? Those functios are already implemented so you can call them like any other function functionName();
The difference it that function body is in super class insted of your extended class.

If you wanna to change function behaviour or add some functionality you can override super class function

public override function functionName():void
{
//you can writhe new code here 
//you also can run this function from superclass super.functionName();
}