sampledowncast.as.bak

《Flash AS3殿堂之路》光盘源码 学习ActionScript 3.0

package org.kingda.book.basicoop.polymorphism
{
	import flash.display.Sprite;

	public class SampleDowncast extends Sprite
	{
		public function SampleDowncast() {
			var foo:Base = new Base();
			var bar:Extender = new Extender();
			var c:Base = bar;
			//print(c);
			print(c as Extender);
			trace ((c as Extender) is Extender);
			print(bar);
		}
		
		private function print(o:Extender):void {
			trace ("that's ok");
			o.hello();
		}
	}
}
class Base {
	public var name:String = "Base";
	public function hello():void {
		trace ("Base:hello()");
	}
}
class Extender extends Base {
	public function Extender() {
		name = "Extender"
	}
	
	override public function hello():void {
		trace ("Extender:hello()");
	}
}