Macromedia flex 2 Manual

Adding custom properties and methods to a component

105

Passing a reference to the component

A loosely coupled component is a highly reusable component that you can easily use in 
different places in one application, or in different applications. To make the component from 

 reusable, you can pass a reference 

to the 

TextArea

 control to the custom component, as the following example shows:

<?xml version="1.0"?>
<!-- mxmlAdvanced/MainPassRefToTA.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
    xmlns:MyComp="myComponents.*">
    
    <mx:TextArea id="myTAMain" />
    <MyComp:StateComboBoxPassRefToTA outputTA="{myTAMain}" />
    
</mx:Application>

The custom component does not have to know anything about the main application, other 
than that it writes its results back to a 

TextArea

 control, as the following example shows:

<?xml version="1.0"?>
<!-- mxmlAdvanced/myComponents/StateComboBoxPassRefToTA.mxml -->

<mx:ComboBox xmlns:mx="http://www.adobe.com/2006/mxml" 
close="handleCloseEvent(event);">

    <mx:Script>
        <![CDATA[               
            import flash.events.Event;
            import mx.controls.TextArea; 
                
            // Define a variable of type mx.controls.TextArea.
            public var outputTA:TextArea;
            
            public function handleCloseEvent(eventObj:Event):void {
                outputTA.text=String(this.selectedIndex);               
            }                       
        ]]>
    </mx:Script>
        
    <mx:dataProvider>
        <mx:String>AK</mx:String>
        <mx:String>AL</mx:String>
    </mx:dataProvider>    
</mx:ComboBox> 

In this example, you use the Flex data binding syntax to pass the reference to the TextArea 
control to your custom component. Now, you can use StateComboBoxPassRefToTA.mxml 
anywhere in an application. The only requirement is that the calling component must pass a 
reference to a TextArea control to the component.