[AS2] Class Parameters and eval ()

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

Code:

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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);
        }
}

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