[dimarik]

var classConstructor:Class = this["constructor"];
...
/*
Вместо
var className:String = getQualifiedClassName(this);
if (className == getQualifiedClassName(Enumeration))
    throw new ArgumentError("Enumeration class cannot be instantiated.");
*/
 
// Можно прост:
if (classConstructor == Enumeration) {
    throw new ArgumentError("Enumeration class cannot be instantiated.");
}

Так, накатило прост.