sampleas.as

《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 SampleAs extends Sprite
	{
		public function SampleAs() {
			var ext:Extender = new Extender();
			var base:Base = ext;
			//base.hello(); //这儿会报错，编译器不会将base识别为Extender类型
			if (base is Extender) {
				(base as Extender).hello();
			}
			//base.hello();
			Extender(base).hello();
		}
	}	
}
class Base {};
class Extender extends Base {
	public function hello():void {
		trace ("Extender:hello()");
	}
}