关闭问题？ - 传递变量的当前值

Question

我试图在单击动态生成的导航“节点”时传递变量的当前值。这需要只是一个整数，但它总是导致最后一个节点的值..尝试了一些不同的方法来传递值，自定义事件侦听器，设置器，但我怀疑这是一个闭包问题.. 帮助将不胜感激;-)

function callGrid():void {

    for (var i:Number = 0; i < my_total; i++) {

        var gridnode_url = my_grid[i].@gridnode;
        var news_category= my_grid[i].@category;
        var newstitle = my_grid[i].@newstitle;
        var news_content = my_grid[i]..news_content;
        var news_image = my_grid[i]..news_image;

        var gridnode_loader = new Loader();
        container_mc.addChild(gridnode_loader);
        container_mc.mouseChildren = false;
        gridnode_loader.load(new URLRequest(gridnode_url));
        gridnode_loader.contentLoaderInfo.addEventListener(Event.COMPLETE, gridLoaded);
        gridnode_loader.name = i;

        text_container_mc = new MovieClip();
        text_container_mc.x = 0;
        text_container_mc.mouseEnabled = false;
        var textY = text_container_mc.y = (my_gridnode_height+18)*y_counter;
        addChild(text_container_mc);
        var tf:TextSplash=new TextSplash(newstitle,10,0,4 );
        container_mc.addChild(tf);
        tf.mouseEnabled = false;
        tf.height = my_gridnode_height;
        text_container_mc.addChild(tf); 
        var text_container_mc_tween = new Tween(text_container_mc, "alpha", Strong.easeIn, 0,1,0.1, true);

        gridnode_loader.x = (my_gridnode_width+5) * x_counter;
        gridnode_loader.y = (my_gridnode_height+15) * y_counter;

        if (x_counter+1 < columns) {
            x_counter++;
        } else {
            x_counter = 0;
            y_counter++;
        }
    }
}
function gridLoaded(e:Event):void {
    var i:uint;
    var my_gridnode:Loader = Loader(e.target.loader);
    container_mc.addChild(my_gridnode);
    _xmlnewstarget = my_gridnode.name;

//||||||||||||||||||||||||||||||||||||||||   
//when a particular grid node is clicked I need to send the current _xmlnewstarget value to the LoadNewsContent function...
//||||||||||||| ||||||||||||||||||||||||

    my_tweens[Number(my_gridnode.name)]=new Tween(my_gridnode, "alpha", Strong.easeIn, 0,1,0.1, true);
    my_gridnode.contentLoaderInfo.removeEventListener(Event.COMPLETE, gridLoaded);
    my_gridnode.addEventListener(MouseEvent.CLICK, loadNewsContent);

}

function loadNewsContent(e:MouseEvent):void {
    createNewsContainer();
    getXMLNewsTarget();
    news_category = my_grid[_xmlnewstarget].@category;
    var tfnews_category:TextSplash=new TextSplash(news_category,20,16,32,false,false,0xffffff );
    tfnews_category.mouseEnabled = false;

    newstitle = my_grid[_xmlnewstarget].@newstitle;
    var tftitle:TextSplash=new TextSplash(newstitle,20,70,24,false,false,0x333333 );
    news_container_mc.addChild(tftitle);
    tftitle.mouseEnabled = false;

    news_content = my_grid[_xmlnewstarget]..news_content;
    var tfnews_content:TextSplash=new TextSplash(news_content,20,110,20,true,true,0x333333,330);
    news_container_mc.addChild(tfnews_content);
    tfnews_content.mouseEnabled = false;
    news_image = my_grid[_xmlnewstarget].@news_image;
    loadNewsImage();
    addChild(tfnews_category);
    addChild(tftitle);
    addChild(tfnews_content);

    var news_container_mc_tween = new Tween(news_container_mc, "alpha", Strong.easeIn, 0,1,0.3, true);
    news_container_mc_tween.addEventListener(Event.INIT, newsContentLoaded);
}

Answer 1

我不会尝试阅读您的代码（尝试处理您的格式，即使它只是缩进），但我将提供一个简化的示例：

for (var i = 0; i < my_total; i++) {
    var closure = function() {
        // use i here
    }
}

正如您所说，当调用closure 时，它将包含i 的最后一个值（在本例中为my_total）。改为这样做：

for (var i = 0; i < my_total; i++) {
    (function(i) {
        var closure = function() {
            // use i here
        }
    })(i);
}

这会在循环内创建 另一个 函数，该函数“捕获”i 的当前值，以便您的闭包可以引用该值。

有关更多类似示例，另请参阅 How does the (function() {})() construct work and why do people use it?。

Answer 2

嗯，上面说了，代码有点密集，但是我想你可能有点字符串和整数的类型转换问题，“最后一个值”总是0吗？尝试进行这些更改，然后告诉我你的进展情况。

// replace this gridnode_loader.name = i;
gridnode_loader.name = i.toString();

// explictly type this as an int
_xmlnewstarget = parseInt(my_gridnode.name);

// replace this: my_tweens[Number(my_gridnode.name)] = new Tween(......
my_tweens[parseInt(my_gridnode.name)] = new Tween();

哦，我认为一旦你得到它的工作，你应该大规模地重构这个代码块是不言而喻的。

编辑：经过进一步研究，我认为你需要这个

//replace this: my_gridnode.addEventListener(MouseEvent.CLICK, loadNewsContent);

var anonHandler:Function = function(e:MouseEvent):void
{
    loadNewsContent(_xmlnewstarget);

};
my_gridnode.addEventListener(MouseEvent.CLICK, anonHandler);

您的loadNewsContent 已将争论从(e:MouseEvent) 更改为(id:String)

Answer 3

首先，您不需要为同一个加载器调用 addChild 两次（一次在 callGrid 中），然后在 (gridLoaded) 中调用。然后您可以尝试放入 loadNewsContent：
news_category = my_grid[int(e.target.name)].@category;
而不是
news_category = my_grid[_xmlnewstarget].@category;
因为 _xmlnewstarget 似乎范围更大，这就是每次加载操作完成时它都会更新的原因。