Programming Flex 3

Reflection

ActionScript 3.0 supports class reflection using the following functions in the flash.utils package:

• getQualifiedClassName

• getQualifiedSuperclassName

• getDefinitionByName

• describeType

Getting the Class Name

You can retrieve the name of the class for which an object is an instance using the getQualifiedClassName() function. The function requires that you pass it a reference to an object; it then returns the fully qualified class name.

var loader:URLLoader = new URLLoader();
var className:String = getQualifiedClassName(loader);
trace(className); // Displays flash.net::URLLoader

If you want to retrieve the fully qualified superclass name for an object, you can use the getQualifiedSuperclassName() function:

var loader:URLLoader = new URLLoader();
var className:String = getQualifiedSuperclassName(loader);
trace(className); // Displays flash.events::EventDispatcher

Getting the Class by Name

If you have a class name, you can retrieve a reference to the class using the getDefinitionByName() function. The function requires a string parameter specifying a fully qualified class name, and it returns an Object type. The function returns an Object type rather than a Class type because it could also theoretically return a reference to a function if you pass it a fully qualified function name (e.g., flash.util.getTimer).

If you’re certain that you’re retrieving a class reference, you can cast the return value to Class, as in the following example:

var classReference:Class = Class(getDefinitionByName("flash.net.URLLoader")); ...