[Flex] ButtonBar系列——labelFunction用户提供的函数，在每个项目上运行以确定其标签

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600">
    
    <fx:Script>
        <![CDATA[
            private var buttonBarXML:XML = describeType(ButtonBar);
            protected function labelFun(item:Object):String
            {
                //trace(buttonBarXML.factory.toString());
                var cat:String = item.label.toUpperCase();
                var len:uint = buttonBarXML.factory.child(item.data).length();
                return item.label + " (" + len + ")";

            }
        ]]>
    </fx:Script>
    
    <fx:Declarations>
        <!-- 将非可视元素（例如服务、值对象）放在此处 -->
        <s:ArrayList id="arr">
            <fx:Array>
                <fx:Object label="Accessors" data="accessor"/>
                <fx:Object label="Methods" data="method"/>
                <fx:Object label="ImplementsInterface" data="implementsInterface"/>
                <fx:Object label="Variable" data="variable"/>
            </fx:Array>
        </s:ArrayList>
    </fx:Declarations>
    <s:ButtonBar id="buttonBar" dataProvider="{arr}" labelFunction="labelFun"  />
</s:Application>