从基础开始深入学Flash AS3教程(4)(译文)

var a:Object = new Object();
var b:Object = a; // b和a引用同一个new Object();
delete a;
trace(b); // 输出[object Object] - 在内存中还是存在
delete b;
// GC将回收object

// ActionScript 2
class DeleteVarClass {
    public var myVar:Number;
    function DeleteVarClass() {
        myVar = 1;
        trace(myVar); // 1
        delete myVar;
        trace(myVar); // undefined
    }
}
// ActionScript 3
package {
    public class DeleteVarClass {
        public var myVar:Number; 
        public function DeleteVarClass() {
            myVar = 1;
            trace(myVar); // 1
            delete myVar;
            trace(myVar); // 1
        }
    }
}

myVar = null;

var obj:Object = new Object();
obj["name"] = 1; // 键是字符串"name"
obj[1] = 2; // 键是1 (被转换成字符串"1")
obj[new Object()] = 3; // 键是new Object()，被转传成字符串"[object Object]"
for (var prop:String in obj) {
     trace(prop); // 输出：[object Object], 1, name
     trace(obj[prop]); // 输出：3, 2, 1
}

也就是说，无论用什么类型的变量作为键，都将被转换成字符串。同时，如果你使用了不同的对象作为键，都会北转换成字符串"[object Object]"作为键，因此而指向了同一个数据。例如：

ActionScript Code:
var a:Object = new Object();
var b:Object = new Object();
var obj:Object = new Object();
obj[a] = 1; // obj["[object Object]"] = 1;
obj[b] = 2; // obj["[object Object]"] = 2;
for (var prop:String in obj) {
     trace(prop); // traces: [object Object]
     trace(obj[prop]); // traces: 2
}

Dictionary类将没有这个限制，你可以将键设置成任何一种数据类型。例如：

import flash.utils.Dictionary;
var a:Object = new Object();
var b:Object = new Object();
var dict:Dictionary = new Dictionary();
dict[a] = 1; // dict[a] = 1;
dict[b] = 2; // dict[b] = 2;
for (var prop:* in dict) {
     trace(prop); // traces: [object Object], [object Object]
     trace(dict[prop]); // traces: 1, 2
}