// 指定某个变量或函数只为每个类创建一次，而不是在基于该类的每个对象中都创建
// 直接使用类名访问静态类成员 someClassName.name

class staticUsage { 
	private static var numInstances:Number = 0; 
	function staticUsage() { 
		numInstances++; 
	} 
	static function get instances():Number { 
		return numInstances; 
	} 
}

/* usage
trace(staticUsage.instances); 
var s1:staticUsage = new staticUsage(); 
trace(staticUsage.instances); 
var s2:staticUsage = new staticUsage(); 
trace(staticUsage.instances); 
*/

/* trace
0
1
2
*/