HOW AND WHY TO ENCAPSULATE CLASS TREES

A good reusable framework, pattern or module interface usually is repr esented by abstract classes. They form an abstract design and leave th e implementation to concrete subclasses. The abstract design is instan tiated by naming these subclasses, Unfortunately, this exposes impleme ntation details like class names and class tree structures. The paper gives a rationale and a general metaobject protocol design that encaps ulates whole class trees, Clients of an abstract design retrieve class es and create objects based on class semantics specifications. Using a bstract classes as the only interface enhances information hiding and makes it easier both to evolve a system and to configure system varian ts.