Can't access object using "id" or "name" if created with actionscript

Question

How can you register an instance of an object with actionscript so that it's id or name value is accessible?
I included a simple example where a Button is created using mxml and in the same way it is created using actionscript.  The actionscript object is inaccessible using it's "id" and "name" property.
<?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"
               creationComplete="application1_creationCompleteHandler(event)">
    <fx:Script>
        <![CDATA[
            import mx.events.FlexEvent;
            protected function application1_creationCompleteHandler(event:FlexEvent):void
                import spark.components.Button;
                var asBtn:Button = new Button();
                asBtn.label = "actionscript";
                asBtn.x = 200;
                asBtn.id = "asButton";
                asBtn.name = "asButtonName";
                addElement(asBtn);
                trace("mxmlButton="+this["mxmlButton"].label); // returns: mxml  label
                //trace("mxmlButton="+this["asButton"].label); // returns runtime error: ReferenceError: Error #1069: Property asButton not found on TestId and there is no default value.
                //trace("mxmlButton="+this["asButtonName"].label); // returns runtime error: ReferenceError: Error #1069: Property asButtonName not found on TestId and there is no default value.
        ]]>
    </fx:Script>
    <s:Button
        id="mxmlButton"
        label="mxml label"
        alpha="0.8"/>
</s:Application>

Answer 1

Hi Dan,
It is a very rare occurrence when I miss not being able to access an object (object property, really) using the ["name"] notation for objects created using actionscript.
In MXML the compiler is conveniently adding an attribute to the class with the same name as the id, so you can conveniently refer to it using the [] notation. While we explicitly specify an application container to use, the MXML compiler creates a custom container which is a derivative of the base container and to that it adds properties for the children declared in MXML. I guess it also effectively calls "addElement" for us when  the container is being constructed.
Your example assumes that using "addElement" to add the button to the application container is the same as declaring a variable (ie property ). It isn't, so there's no point in looking for an property of the name "as3Button" using the [] notation, because it doesn't exist. The container is managing a collection of children in it's display list and that's not the same as being accessible as properties of the container.
Generally speaking, accessing properties using the ["name"] syntax isn't necessary.
Paul
[edit: you may wonder why "addElement" doesn't conveniently also add the "id" attribute to be an property of the container class. Unfortunately, it can't because the container class would need to be dynamic and it's not. A further complication would be that adding properties at runtime would invite naming clashes at runtime with associated mayhem. MXML can do this because the compiler generates the class and can trap name duplication at compile time.
Great question, BTW.
-last edit changed my "attributes" to be "properties" in line with Adobe's terminology]