面向对象数据库中的视图

A View in Object-oriented Database Systems

本文将在Ｓｍａｌｔａｌｋ环境中讨论面向对象数据库（ＯＯＤＢ）中的视图实现方法。首先定义一些基本方法来获得一个类的所有实例和子类；然后提出用虚类（用Ｓｍａｌｔａｌｋ程序定义的各种各样视图）和结构视图（把用户不感兴趣的类转变为抽象类的子类－超类层次结构）来实现视图机制的方法。

This paper mainly discusses the realization mechanism of views in Object-oriented Database(OODB),especially in the environment of Smalltalk. In this paper, some basic methods are first defined to obtain all the instances and subclasses of a class, and the method that the view mechanism is realized by virtual classes(a wide variety of views defined by a Smalltalk program) and structural views(the subclass-superclass hierarchies obtained to change all the classes, in which a user is not interested, into abstract classes) is given.