在工厂模式中使用VB.NET对象初始值设定项

I have written a base class from which I wish to derive several child classes (in this case Windows Form classes), and I'm using a Factory pattern in order to maintain a collection of the child instances, so that a form can only have one instance per primary key value (sort of a mash-up of Factory and Singleton patterns.)I have written a base class from which I wish t