Declares cf to be the class factory.
[in] The name of the class that implements your class factory object.
The cf parameter must derive from CComClassFactory and override the CreateInstance method.
CComCoClass includes the DECLARE_CLASSFACTORY macro, which specifies CComClassFactory as the default class factory. However, by including the DECLARE_CLASSFACTORY_EX macro in your object's class definition, you override this default.