Programming Flex 3

Adding Custom Properties and Events

When creating components, you will often want to declare some sort of public API. It is typically advisable that you create properties rather than methods with components. Doing so will allow component properties to be set more naturally within MXML as attributes, because methods are not declaratively called within MXML.

You create a public property in a custom component by creating a getter/setter. For the StatusIcon component, one feature you might want to have is the ability to set the status of the component. The status could be a public property that you can set and whose value you could retrieve. Also, the property should be bindable. To create the property you first declare the getter/setter function and make it bindable via [Bindable] metadata:

public static const STATUS_AVAILABLE:String = "available";
public static const STATUS_BUSY:String = "busy";
public static const STATUS_IDLE:String = "idle";

private var _status:String;
private var statusChanged:Boolean = false;

[Bindable]
public function set status(value:String):void
{
    _status = value;
    statusChanged = true;
    invalidateProperties();
}

public function get status():String
{
    return _status;
}

Next, you will need to update the commitProperties() method to support the new property. You first declare public constant values for the different values that the setter supports. Although ActionScript 3 does not support enumerations, declaring public properties for valid values is a good practice ...