User Guide

48 Using Metadata Tags in Custom Components

In this example, you add the [Event] metadata tag before the class definition to indicate that

the class dispatches an event named

enableChanged. You also include the [Inspectable]

metadata tag to indicate that the

enableTA property is accessible in Flex Builder.

In an MXML file, you insert the metadata tags either in an

<mx:Script> block along with

your ActionScript code, or in an

<mx:Metadata> block, as the following example shows:

<?xml version="1.0"?>

<mx:TextArea xmlns:mx="http://www.adobe.com/2006/mxml">

<mx:Metadata>

[Event(name="enableChange", type="flash.events.Event")]

</mx:Metadata>

<mx:Script>

<![CDATA[

// Import Event class.

import flash.events.Event;

// Define class properties and methods.

private var _enableTA:Boolean;

// Add the [Inspectable] metadata tag before the individual property.

[Inspectable(defaultValue="false")]

public function set enableTA(val:Boolean):void {

_enableTA = val;

this.enabled = val;

// Define event object, initialize it, then dispatch it.

var eventObj:Event = new Event("enableChange");

dispatchEvent(eventObj);

}

]]>

</mx:Script>

</mx:TextArea>

A key difference between the <mx:Metadata> and <mx:Script> tags is that text within the

<mx:Metadata> tag is inserted before the generated class declaration, but text within

<mx:Script> tag is inserted in the body of the generated class declaration. Therefore,

metadata tags like

[Event] and [Effect] must go in an <mx:Metadata> tag, but the

[Bindable] and [Embed] metadata tags must go in an <mx:Script> tag.