as3 duplicateMovieClip Replacement

source : here

ActionScript 3 no longer has a duplicateMovieClip method for MovieClip instances (or any DisplayObject instances). Instead, it's suggested that you just create a new instance of the display object you wish to duplicate using its constructor. This, however, is not the same as duplicateMovieClip, and, really, is more like using AS1 and AS2's attachMovieClip. For a more accurate representation of duplicateMovieClip in AS3, consider the following function:

package com.senocular.display {

import flash.display.DisplayObject;
import flash.geom.Rectangle;

/**
* duplicateDisplayObject
* creates a duplicate of the DisplayObject passed.
* similar to duplicateMovieClip in AVM1
* @param target the display object to duplicate
* @param autoAdd if true, adds the duplicate to the display list
* in which target was located
* @return a duplicate instance of target
*/
public function duplicateDisplayObject(target:DisplayObject, autoAdd:Boolean = false):DisplayObject {
// create duplicate
var targetClass:Class = Object(target).constructor;
var duplicate:DisplayObject = new targetClass();

// duplicate properties
duplicate.transform = target.transform;
duplicate.filters = target.filters;
duplicate.cacheAsBitmap = target.cacheAsBitmap;
duplicate.opaqueBackground = target.opaqueBackground;
if (target.scale9Grid) {
var rect:Rectangle = target.scale9Grid;
// Flash 9 bug where returned scale9Grid is 20x larger than assigned
rect.x /= 20, rect.y /= 20, rect.width /= 20, rect.height /= 20;
duplicate.scale9Grid = rect;
}

// add to target parent's display list
// if autoAdd was provided as true
if (autoAdd && target.parent) {
target.parent.addChild(duplicate);
}
return duplicate;
}
}

usage:
import com.senocular.display.duplicateDisplayObject;

// create duplicate and assign to newInstance variable
// using true for autoAdd automatically adds the newInstance
// into the display list where myOldSprite is located
var newInstance:Sprite = duplicateDisplayObject(myOldSprite, true);
newInstance.x += 100; // shift to see duplicate


The only thing duplicateMovieClip does that this does not is copy dynamic drawing information. Currently, the graphics object in display objects cannot be duplicated so there is no way to obtain that information for duplicates in duplicateDisplayObject.