Extending the MovieClip class

Using ActionScript 2 and object-oriented programming techniques, you can extend the behavior of the default MovieClip class. For more information about ActionScript 2 see Creating classes with ActionScript 2.

To extend, or subclass, the MovieClip class, you use the extends statement to specify MovieClip as the superclass of your custom class. The example code shown below create a subclass called Ball of the MovieClip object. This class overrides the MovieClip.onEnterFrame() method to move the clip (that this the class is applied to) five pixels to the right at each new frame.

// Ball class -- moves symbol to the right five pixels every frame

class Ball extends MovieClip {

	function onEnterFrame() {
		_x += 5;
	}
}