describeType Reflection

The describeType utility function generates xml from a given class. It’s pretty straight forward:

trace(describeType(MovieClip));

Will give us this chunk of xml:

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<type name="flash.display::MovieClip" base="Class" isDynamic="true" isFinal="true" isStatic="true">
  <extendsClass type="Class"/>
  <extendsClass type="Object"/>
  <accessor name="prototype" access="readonly" type="*" declaredBy="Class"/>
  <factory type="flash.display::MovieClip">
    <extendsClass type="flash.display::Sprite"/>
    <extendsClass type="flash.display::DisplayObjectContainer"/>
    <extendsClass type="flash.display::InteractiveObject"/>
    <extendsClass type="flash.display::DisplayObject"/>
    <extendsClass type="flash.events::EventDispatcher"/>
    <extendsClass type="Object"/>
    <implementsInterface type="flash.events::IEventDispatcher"/>
    <implementsInterface type="flash.display::IBitmapDrawable"/>
    <accessor name="root" access="readonly" type="flash.display::DisplayObject" declaredBy="flash.display::DisplayObject"/>
    <accessor name="stage" access="readonly" type="flash.display::Stage" declaredBy="flash.display::DisplayObject"/>
    <accessor name="scenes" access="readonly" type="Array" declaredBy="flash.display::MovieClip"/>
    <accessor name="alpha" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="visible" access="readwrite" type="Boolean" declaredBy="flash.display::DisplayObject"/>
    <accessor name="graphics" access="readonly" type="flash.display::Graphics" declaredBy="flash.display::Sprite"/>
    <accessor name="mask" access="readwrite" type="flash.display::DisplayObject" declaredBy="flash.display::DisplayObject"/>
    <accessor name="currentLabel" access="readonly" type="String" declaredBy="flash.display::MovieClip"/>
    <accessor name="mouseX" access="readonly" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="currentFrameLabel" access="readonly" type="String" declaredBy="flash.display::MovieClip"/>
    <accessor name="mouseY" access="readonly" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="scaleZ" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="currentLabels" access="readonly" type="Array" declaredBy="flash.display::MovieClip"/>
    <accessor name="rotationX" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="rotationY" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="rotationZ" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="cacheAsBitmap" access="readwrite" type="Boolean" declaredBy="flash.display::DisplayObject"/>
    <accessor name="tabIndex" access="readwrite" type="int" declaredBy="flash.display::InteractiveObject"/>
    <accessor name="opaqueBackground" access="readwrite" type="Object" declaredBy="flash.display::DisplayObject"/>
    <accessor name="scrollRect" access="readwrite" type="flash.geom::Rectangle" declaredBy="flash.display::DisplayObject"/>
    <accessor name="filters" access="readwrite" type="Array" declaredBy="flash.display::DisplayObject"/>
    <accessor name="width" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="blendMode" access="readwrite" type="String" declaredBy="flash.display::DisplayObject"/>
    <accessor name="transform" access="readwrite" type="flash.geom::Transform" declaredBy="flash.display::DisplayObject"/>
    <accessor name="name" access="readwrite" type="String" declaredBy="flash.display::DisplayObject"/>
    <accessor name="scale9Grid" access="readwrite" type="flash.geom::Rectangle" declaredBy="flash.display::DisplayObject"/>
    <accessor name="mouseChildren" access="readwrite" type="Boolean" declaredBy="flash.display::DisplayObjectContainer"/>
    <accessor name="tabChildren" access="readwrite" type="Boolean" declaredBy="flash.display::DisplayObjectContainer"/>
    <accessor name="height" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="useHandCursor" access="readwrite" type="Boolean" declaredBy="flash.display::Sprite"/>
    <accessor name="accessibilityImplementation" access="readwrite" type="flash.accessibility::AccessibilityImplementation" declaredBy="flash.display::InteractiveObject">
      <metadata name="Inspectable">
        <arg key="environment" value="none"/>
      </metadata>
    </accessor>
    <accessor name="focusRect" access="readwrite" type="Object" declaredBy="flash.display::InteractiveObject"/>
    <accessor name="loaderInfo" access="readonly" type="flash.display::LoaderInfo" declaredBy="flash.display::DisplayObject"/>
    <accessor name="accessibilityProperties" access="readwrite" type="flash.accessibility::AccessibilityProperties" declaredBy="flash.display::DisplayObject"/>
    <accessor name="scaleX" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="buttonMode" access="readwrite" type="Boolean" declaredBy="flash.display::Sprite"/>
    <accessor name="scaleY" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="dropTarget" access="readonly" type="flash.display::DisplayObject" declaredBy="flash.display::Sprite"/>
    <accessor name="blendShader" access="writeonly" type="flash.display::Shader" declaredBy="flash.display::DisplayObject"/>
    <accessor name="trackAsMenu" access="readwrite" type="Boolean" declaredBy="flash.display::MovieClip"/>
    <accessor name="parent" access="readonly" type="flash.display::DisplayObjectContainer" declaredBy="flash.display::DisplayObject"/>
    <accessor name="hitArea" access="readwrite" type="flash.display::Sprite" declaredBy="flash.display::Sprite"/>
    <accessor name="soundTransform" access="readwrite" type="flash.media::SoundTransform" declaredBy="flash.display::Sprite"/>
    <accessor name="mouseEnabled" access="readwrite" type="Boolean" declaredBy="flash.display::InteractiveObject"/>
    <accessor name="rotation" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="numChildren" access="readonly" type="int" declaredBy="flash.display::DisplayObjectContainer"/>
    <accessor name="x" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="y" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="z" access="readwrite" type="Number" declaredBy="flash.display::DisplayObject"/>
    <accessor name="doubleClickEnabled" access="readwrite" type="Boolean" declaredBy="flash.display::InteractiveObject"/>
    <accessor name="textSnapshot" access="readonly" type="flash.text::TextSnapshot" declaredBy="flash.display::DisplayObjectContainer"/>
    <accessor name="contextMenu" access="readwrite" type="flash.ui::ContextMenu" declaredBy="flash.display::InteractiveObject"/>
    <accessor name="tabEnabled" access="readwrite" type="Boolean" declaredBy="flash.display::InteractiveObject"/>
    <accessor name="currentScene" access="readonly" type="flash.display::Scene" declaredBy="flash.display::MovieClip"/>
    <accessor name="currentFrame" access="readonly" type="int" declaredBy="flash.display::MovieClip"/>
    <accessor name="framesLoaded" access="readonly" type="int" declaredBy="flash.display::MovieClip"/>
    <accessor name="totalFrames" access="readonly" type="int" declaredBy="flash.display::MovieClip"/>
    <accessor name="enabled" access="readwrite" type="Boolean" declaredBy="flash.display::MovieClip"/>
    <method name="getChildAt" declaredBy="flash.display::DisplayObjectContainer" returnType="flash.display::DisplayObject">
      <parameter index="1" type="int" optional="false"/>
    </method>
    <method name="addEventListener" declaredBy="flash.events::EventDispatcher" returnType="void">
      <parameter index="1" type="String" optional="false"/>
      <parameter index="2" type="Function" optional="false"/>
      <parameter index="3" type="Boolean" optional="true"/>
      <parameter index="4" type="int" optional="true"/>
      <parameter index="5" type="Boolean" optional="true"/>
    </method>
    <method name="dispatchEvent" declaredBy="flash.events::EventDispatcher" returnType="Boolean">
      <parameter index="1" type="flash.events::Event" optional="false"/>
    </method>
    <method name="hasEventListener" declaredBy="flash.events::EventDispatcher" returnType="Boolean">
      <parameter index="1" type="String" optional="false"/>
    </method>
    <method name="toString" declaredBy="flash.events::EventDispatcher" returnType="String"/>
    <method name="willTrigger" declaredBy="flash.events::EventDispatcher" returnType="Boolean">
      <parameter index="1" type="String" optional="false"/>
    </method>
    <method name="removeEventListener" declaredBy="flash.events::EventDispatcher" returnType="void">
      <parameter index="1" type="String" optional="false"/>
      <parameter index="2" type="Function" optional="false"/>
      <parameter index="3" type="Boolean" optional="true"/>
    </method>
    <method name="areInaccessibleObjectsUnderPoint" declaredBy="flash.display::DisplayObjectContainer" returnType="Boolean">
      <parameter index="1" type="flash.geom::Point" optional="false"/>
    </method>
    <method name="globalToLocal" declaredBy="flash.display::DisplayObject" returnType="flash.geom::Point">
      <parameter index="1" type="flash.geom::Point" optional="false"/>
    </method>
    <method name="localToGlobal" declaredBy="flash.display::DisplayObject" returnType="flash.geom::Point">
      <parameter index="1" type="flash.geom::Point" optional="false"/>
    </method>
    <method name="getBounds" declaredBy="flash.display::DisplayObject" returnType="flash.geom::Rectangle">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
    </method>
    <method name="getRect" declaredBy="flash.display::DisplayObject" returnType="flash.geom::Rectangle">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
    </method>
    <method name="prevScene" declaredBy="flash.display::MovieClip" returnType="void"/>
    <method name="nextScene" declaredBy="flash.display::MovieClip" returnType="void"/>
    <method name="hitTestObject" declaredBy="flash.display::DisplayObject" returnType="Boolean">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
    </method>
    <method name="setChildIndex" declaredBy="flash.display::DisplayObjectContainer" returnType="void">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
      <parameter index="2" type="int" optional="false"/>
    </method>
    <method name="hitTestPoint" declaredBy="flash.display::DisplayObject" returnType="Boolean">
      <parameter index="1" type="Number" optional="false"/>
      <parameter index="2" type="Number" optional="false"/>
      <parameter index="3" type="Boolean" optional="true"/>
    </method>
    <method name="globalToLocal3D" declaredBy="flash.display::DisplayObject" returnType="flash.geom::Vector3D">
      <parameter index="1" type="flash.geom::Point" optional="false"/>
    </method>
    <method name="contains" declaredBy="flash.display::DisplayObjectContainer" returnType="Boolean">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
    </method>
    <method name="startDrag" declaredBy="flash.display::Sprite" returnType="void">
      <parameter index="1" type="Boolean" optional="true"/>
      <parameter index="2" type="flash.geom::Rectangle" optional="true"/>
    </method>
    <method name="removeChildAt" declaredBy="flash.display::DisplayObjectContainer" returnType="flash.display::DisplayObject">
      <parameter index="1" type="int" optional="false"/>
    </method>
    <method name="local3DToGlobal" declaredBy="flash.display::DisplayObject" returnType="flash.geom::Point">
      <parameter index="1" type="flash.geom::Vector3D" optional="false"/>
    </method>
    <method name="getChildIndex" declaredBy="flash.display::DisplayObjectContainer" returnType="int">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
    </method>
    <method name="stopTouchDrag" declaredBy="flash.display::Sprite" returnType="void">
      <parameter index="1" type="int" optional="false"/>
      <metadata name="API">
        <arg key="" value="667"/>
      </metadata>
    </method>
    <method name="stop" declaredBy="flash.display::MovieClip" returnType="void"/>
    <method name="stopDrag" declaredBy="flash.display::Sprite" returnType="void"/>
    <method name="getChildByName" declaredBy="flash.display::DisplayObjectContainer" returnType="flash.display::DisplayObject">
      <parameter index="1" type="String" optional="false"/>
    </method>
    <method name="startTouchDrag" declaredBy="flash.display::Sprite" returnType="void">
      <parameter index="1" type="int" optional="false"/>
      <parameter index="2" type="Boolean" optional="true"/>
      <parameter index="3" type="flash.geom::Rectangle" optional="true"/>
      <metadata name="API">
        <arg key="" value="667"/>
      </metadata>
    </method>
    <method name="swapChildren" declaredBy="flash.display::DisplayObjectContainer" returnType="void">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
      <parameter index="2" type="flash.display::DisplayObject" optional="false"/>
    </method>
    <method name="swapChildrenAt" declaredBy="flash.display::DisplayObjectContainer" returnType="void">
      <parameter index="1" type="int" optional="false"/>
      <parameter index="2" type="int" optional="false"/>
    </method>
    <method name="getObjectsUnderPoint" declaredBy="flash.display::DisplayObjectContainer" returnType="Array">
      <parameter index="1" type="flash.geom::Point" optional="false"/>
    </method>
    <method name="play" declaredBy="flash.display::MovieClip" returnType="void"/>
    <method name="addChild" declaredBy="flash.display::DisplayObjectContainer" returnType="flash.display::DisplayObject">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
    </method>
    <method name="nextFrame" declaredBy="flash.display::MovieClip" returnType="void"/>
    <method name="prevFrame" declaredBy="flash.display::MovieClip" returnType="void"/>
    <method name="addChildAt" declaredBy="flash.display::DisplayObjectContainer" returnType="flash.display::DisplayObject">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
      <parameter index="2" type="int" optional="false"/>
    </method>
    <method name="gotoAndPlay" declaredBy="flash.display::MovieClip" returnType="void">
      <parameter index="1" type="Object" optional="false"/>
      <parameter index="2" type="String" optional="true"/>
    </method>
    <method name="removeChild" declaredBy="flash.display::DisplayObjectContainer" returnType="flash.display::DisplayObject">
      <parameter index="1" type="flash.display::DisplayObject" optional="false"/>
    </method>
    <method name="gotoAndStop" declaredBy="flash.display::MovieClip" returnType="void">
      <parameter index="1" type="Object" optional="false"/>
      <parameter index="2" type="String" optional="true"/>
    </method>
    <method name="addFrameScript" declaredBy="flash.display::MovieClip" returnType="void">
      <metadata name="Inspectable">
        <arg key="environment" value="none"/>
      </metadata>
    </method>
  </factory>
</type>

When dealing with regular objects we can iterate over their properties like this:

var o:Object = {a:1, b:2, c:3};
 
for (var i:String in o){
	trace(i, "=", o[i]);
}

Which results in:

a = 1
b = 2
c = 3

Trying to do the same over a MovieClip only works for dynamic properties:

var clip:MovieClip = new MovieClip();
clip.dynamicProp = 1;
for (var i:String in clip){
	trace(i, "=", clip[i]);
}

Resulting in:

dynamicProp = 1

If we want to see all the other properties we need to use describeType:

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var clip:MovieClip = new MovieClip();
 
getProps(clip);
 
function getProps(target:*):void{
	var description:XML = describeType(target);
	var i:XML,name:String,access:String;
 
	for each (i in description.accessor){
		access = i.@access;
		name = i.@name;
		if (access == "readonly"){
			traceProp(target, name);
		}else if (access == "readwrite"){
			traceProp(target, name);
		}else{
			// writeonly
			trace(name);
		}
	}
}
 
function traceProp(target:*, key:*):void{
	trace(key, "=", target[key]);
}

Which will give us:

root = null
stage = null
scenes = [object Scene]
alpha = 1
visible = true
graphics = [object Graphics]
mask = null
currentLabel = null
mouseX = 800
currentFrameLabel = null
mouseY = 445
scaleZ = 1
currentLabels =
rotationX = 0
rotationY = 0
rotationZ = 0
cacheAsBitmap = false
tabIndex = -1
opaqueBackground = null
scrollRect = null
filters =
width = 0
blendMode = normal
transform = [object Transform]
name = instance1
scale9Grid = null
mouseChildren = true
tabChildren = true
height = 0
useHandCursor = true
accessibilityImplementation = null
focusRect = null
loaderInfo = null
accessibilityProperties = null
scaleX = 1
buttonMode = false
scaleY = 1
dropTarget = null
blendShader
trackAsMenu = false
parent = null
hitArea = null
soundTransform = [object SoundTransform]
mouseEnabled = true
rotation = 0
numChildren = 0
x = 0
y = 0
z = 0
doubleClickEnabled = false
textSnapshot = [object TextSnapshot]
contextMenu = null
tabEnabled = false
currentScene = [object Scene]
currentFrame = 0
framesLoaded = 1
totalFrames = 1
enabled = true

Getting at the method signatures doesn’t require too much additional work:

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var clip:MovieClip = new MovieClip();
 
getInfo(clip);
 
function getInfo(target:*):void{
	var description:XML = describeType(target);
	var i:XML,name:String,access:String;
 
	for each (i in description.accessor){
		access = i.@access;
		name = i.@name;
		if (access == "readonly"){
			traceProp(target, name);
		}else if (access == "readwrite"){
			traceProp(target, name);
		}else{
			// writeonly
			trace(name);
		}
	}
	for each (i in description.method){
		traceMethod(i);
	}
}
function traceMethod(node:XML):void{
	var signature:String = node.@name + "(";
	var optional:Boolean = false;
	var type:String;
	if (node.parameter.length()){
		for each (var i in node.parameter){
			if (i.@optional == "true" && ! optional){
				optional = true;
				signature +=  "[";
			}
			// remove package name;
			type = i.@type;
			type = type.replace(/(.*?)::/,"");
 
			signature +=  type + ",";
		}
		signature = signature.substr(0,signature.length - 1);
		if (optional){
			signature +=  "]";
		}
	}
	signature +=  ")";
	trace(signature);
}
 
function traceProp(target:*, key:*):void{
	//trace(key, "=", target[key]);
}

I’ve commented out the implementation of traceProp() to avoid clutter, so the result is:

blendShader
getChildAt(int)
addEventListener(String,Function,[Boolean,int,Boolean])
dispatchEvent(Event)
hasEventListener(String)
toString()
willTrigger(String)
removeEventListener(String,Function,[Boolean])
areInaccessibleObjectsUnderPoint(Point)
globalToLocal(Point)
localToGlobal(Point)
getBounds(DisplayObject)
getRect(DisplayObject)
prevScene()
nextScene()
hitTestObject(DisplayObject)
setChildIndex(DisplayObject,int)
hitTestPoint(Number,Number,[Boolean])
globalToLocal3D(Point)
contains(DisplayObject)
startDrag([Boolean,Rectangle])
removeChildAt(int)
local3DToGlobal(Vector3D)
getChildIndex(DisplayObject)
stopTouchDrag(int)
stop()
stopDrag()
getChildByName(String)
startTouchDrag(int,[Boolean,Rectangle])
swapChildren(DisplayObject,DisplayObject)
swapChildrenAt(int,int)
getObjectsUnderPoint(Point)
play()
addChild(DisplayObject)
nextFrame()
prevFrame()
addChildAt(DisplayObject,int)
gotoAndPlay(Object,[String])
removeChild(DisplayObject)
gotoAndStop(Object,[String])
addFrameScript()

I like this approach for reflection. It’s very flexible. There are lots of applications for this type of thing. I assume that things like MonsterDebugger make heavy use of this.

Awhile back I started working on something that would automatically generate UI for a given class. I didn’t take it very far…. have a look: http://actionsnippet.com/?p=1425

Digg



This entry was posted on Monday, April 25th, 2011 and is filed under ActionScript. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response or Trackback from your own site.

 
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