How do I dynamically instantiate a class, and set a property at runtime in Flex 3?

Using org.as3commons.reflect I can look-up the class name, and instantiate a class at runtime. I also have (non-working) code which invokes a method. However, I really want to set a property value. I'm not sure if properties are realized as methods internally in Flex.

I have a Metadata class which stores 3 pieces of information: name, value, and type (all are strings). I want to be able to loop through an Array of Metadata objects and set the corresponding properties on the instantiated class.

package com.acme.reporting.builders
{
 import com.acme.reporting.model.Metadata;

 import mx.core.UIComponent;

 import org.as3commons.reflect.ClassUtils;
 import org.as3commons.reflect.MethodInvoker;

 public class UIComponentBuilder implements IUIComponentBuilder
 {
  public function build(metadata:Array):UIComponent
  {
   var typeClass:Class = ClassUtils.forName(getTypeName(metadata));
   var result:* = ClassUtils.newInstance(typeClass);

   for each (var m:Metadata in metadata)
   {
    if (m.name == "type")
     continue;

    // Attempting to invoke as method,
                // would really like the property though

    var methodInvoker:MethodInvoker = n开发者_C百科ew MethodInvoker();

    methodInvoker.target = result;
    methodInvoker.method = m.name;
    methodInvoker.arguments = [m.value];

    var returnValue:* = methodInvoker.invoke(); // Fails!
   }

   return result;
  }

  private static function getTypeName(metadata:Array):String
  {
   if (metadata == null || metadata.length == 0)
    throw new ArgumentError("metadata is null or empty");

   var typeName:String;

   // Type is usually the first entry
   if (metadata.length > 1 && metadata[0] != null && metadata[0].name == "type")
   {
    typeName = metadata[0].value;
   }
   else
   {
    var typeMetadata:Array = metadata.filter(
     function(element:*, index:int, arr:Array):Boolean
     {
      return element.name == "type";
     }
    );

    if (typeMetadata == null || typeMetadata.length != 1)
     throw new ArgumentError("type entry not found in metadata");

    typeName = typeMetadata[0].value;
   }

   if (typeName == null || typeName.length == 0)
    throw new Error("typeName is null or blank");

   return typeName;
  }
 }
}

Here's some usage code:

var metadata:Array = new Array();

metadata[0] = new Metadata("type", "mx.controls.Text", null);
metadata[1] = new Metadata("text", "Hello World!", null);
metadata[2] = new Metadata("x", "77", null);
metadata[3] = new Metadata("y", "593", null);

this.addChild(new UIComponentBuilder().build(metadata));

I realize that I have to declare a dummy variable of the type I was to instantiate, or use the -inculde compiler directive. An unfortunate drawback of Flex.

Also, right now there's code to account for typecasting the value to it's specified type.

Dynamic execution in AS3 is much simpler than in other languages. This code:

var methodInvoker:MethodInvoker = new MethodInvoker();

methodInvoker.target = result;
methodInvoker.method = m.name;
methodInvoker.arguments = [m.value];

var returnValue:* = methodInvoker.invoke(); // Fails!

can be simplified to this:

var returnValue:* = result[method](m.value);

EDIT:

Since it's a property, it would be done like this:

result[method] = m.value;

and there is no return value (well, you can call the getter again but it should just return m.value unless the setter/getter do something funky.