若对于每一个类型S的对象o1,都存在一个类型T的对象o2,使得在所有针对T编写的程序P中,用o1替换o2后,程序P的行为功能不变,则S是T的子类型。
What is wanted here is something like the following
substitution property: If for each object o1 of type S there is an object o2
of type T such that for all programs P defined in terms of T, the behavior of P
is unchanged when o1 is substituted for o2 then S is a subtype of T.
时间: 2024-10-31 17:58:23