Referencing a variable with a string

Hey guys,

I have a bunch of variables:

    [Embed(source="../assets/illustration.png")] public var illustration:Class;
    [Embed(source="../assets/illustration.png")] public var aboutme:Class;
    [Embed(source="../assets/illustration.png")] public var web:Class;
    [Embed(source="../assets/illustration.png")] public var photography:Class;    

And I am trying to call them with a string. So:

var test:Bitmap = new (STRING) as Bitmap;

Obviously the above example doesn’t work, I have tried using getDefinitionByName but to no avail, any ideas?