字段在Qooxdoo库中作为静态字段 [英] Fields are as static fields in Qooxdoo library

问题描述

我想使用qx-oo（Qooxdoo）作为OOP库。但我对场外成员的奇怪行为感到困惑。看起来这些字段在一个类的所有对象之间共享，就像静态成员一样。例如，此测试代码

I'd like to use qx-oo (Qooxdoo) as OOP library. But I was confused by strange behaviour of field members. It's looks like that fields are shared between all objects of one class, like static members. For example, this test code

    qx.Class.define("com.BaseClass",
    {
        extend : qx.core.Object,

        members:
        {
            _children: [],

            getChildrenCount: function(){
                return this._children.length;
            },

            addChild: function(child){
                this._children.push(child);
            }
        }
    });

    var class1 = new com.BaseClass();
    var class2 = new com.BaseClass();
    showLog("class1.getChildrenCount() - " + class1.getChildrenCount())
    showLog("class2.getChildrenCount() - " + class2.getChildrenCount())
    class1.addChild("somechild");
    showLog("class1.getChildrenCount() - " + class1.getChildrenCount())
    showLog("class2.getChildrenCount() - " + class2.getChildrenCount())

将生成此类日志

class1.getChildrenCount() - 0
class2.getChildrenCount() - 0
class1.getChildrenCount() - 1
class2.getChildrenCount() - 1

有没有办法实现这个目标？

Is there a way to accomplish this?

或者你能建议另一个OOP吗？ -js-lib？

这是一个完整的示例。

推荐答案

这不是qooxdoo的问题。您不应该在类描述上初始化引用类型。你应该用构造函数初始化引用类型。

This is not a issue from qooxdoo. You should not initialize reference types on the class description. You should initialize reference types with the constructor.

qooxdoo中有一篇好文章手册解释了这个问题。

There is a good article in the qooxdoo manual which explains the problem.

这是你的改进示例：

    qx.Class.define("com.BaseClass",
    {
        extend : qx.core.Object,

        construct: function() {
          this._children = [];
        },

        members:
        {
            _children: null,

            getChildrenCount: function(){
                return this._children.length;
            },

            addChild: function(child){
                this._children.push(child);
            }
        }
    });

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