Change Pointer/Reference

Hello. I’m new to flex and actionscript and I am trying to figure out if you can change the reference pointer of an object. Basically I have an Object Obj and now I want Obj to point to some new Object I created someplace else. is this possible?

Here is an example of what I want to do…

var obj:Oject = {x:12,y:15};

function f(a:Object):void{
    var t:Object = {z1:55,z2:67};
    a = t;
}

f(obj);
Alert.show(obj.z1);//should display 55

I know this doesn’t work but I am wondering if there is a way to make this work. I’m trying to deal with an event handler that is used to set several different variables it gets from a database so the returns are asynchronous.