子类型的指称语义

The Denotational Semantics of Subtyping

继承被认为是面向对象程序设计的重要特征之一，如何解释继承一直是面向对象形式语义研究的难题．本文针对继承关系的一种形式一一对象间行为规范的继承，即子类型关系，探讨了其指称语义．基本思想是将子类型关系视为类型强制，通过类型强制函数将子类型对象解释父类型域中．

Inheritance is one of the important features of object oriented programming.The explanation of inheritance is always a challenge to the research on formal semantics of object oriented program.In this paper,the denotational semantics of subtyping,a kind of forms of inheritance which describes the inheritance relationship between behavioral specifications of objects,is presented.The basic idea is to view subtyping as type coercion,explaining the objects of subtype into the domain of its supertype by a type coercion function.