[AS2] Class Parameters and eval ()

[menewb]

What is happening here? Cuz I hav noooo clue, and been trying to figure it out for hours
Flash Version 8.0.0

class Tile {
	public var walkable:Boolean;
	public var frame:Number
	static var tile0, tile1, tileF:Object;
	public function Tile (id:Number) {
		var tile:Object = tileClass ("tile1");
		walkable = tile.walkable;
		frame = tile.frame;
	        trace(tile) //outputs undefined
	}
	static function tileClass (str:String) {
		tile0 = {walkable:true, frame:1}
		tile1 = {walkable:false, frame:2}
		tileF = {walkable:false, frame:20}
	        trace (eval(str)); //outputs undefined
	        trace (str); // outputs tile1
	        trace(str==="tile1");// outputs true
	        trace (eval("tile1")); // outputs [object][object]
		return eval(str);
	}
}

Feel free to copy and paste this and try it out, Thanks for any help I can get!