Base class for dynamic factory classes

 This is a simple module that factory classes can use to generate new
 types of objects on the fly, providing a consistent interface to common
 groups of objects.
 .
 Factory classes are used when you have different implementations for
 the same set of tasks but may not know in advance what implementations
 you will be using. With a factory class this is easy. Class::Factory
 even provides a simple constructor for you.