Adobe FLEX 2 - CREATING AND EXTENDING COMPONENTS Manual page 198

The following code shows the implementation of MyTemplateComponent:
<?xml version="1.0"?>
<!-- templating/myComponents/MyTemplateComponent.mxml -->
<mx:VBox xmlns:mx="http://www.adobe.com/2006/mxml"
initialize="init();">
<mx:Script>
<![CDATA[
import mx.containers.HBox;
import mx.core.UIComponent;
// Define a property for the top component.
public var topRow:UIComponent;
// Define an Array of properties for a row of components.
// Restrict the type of the Array elements
// to mx.core.UIComponent.
[ArrayElementType("mx.core.UIComponent")]
public var bottomRow:Array;
private function init():void {
// Add the top component to the VBox container.
addChild(topRow);
// Create an HBox container. This container
// is the parent container of the bottom row of components.
var controlHBox:HBox = new HBox();
// Add the bottom row of components
// to the HBox container.
for (var i:int = 0; i < bottomRow.length; i++)
// Add the HBox container to the VBox container.
addChild(controlHBox);
}
]]>
</mx:Script>
</mx:VBox>
For the bottomRow property, you define it as an Array and include the
metadata tag to specify to the compiler that the data type of the Array elements is also
UIComponent. For more information on the
Chapter 5, "Using Metadata Tags in Custom Components," on page
198 Creating Template Components
controlHBox.addChild(bottomRow[i]);
[ArrayElementType]
[ArrayElementType]
metadata tag, see
45.