Sometimes the functions -- sometimes a function can be used on multiple data types, plus, for example, we saw could add strings, or could add ints, but each one of those data types has associated with it a set of functions that are geared to handling them.

比如说，我们可以对string类型,进行add操作,也可以对int类型进行这个操作，但是这些数据类型中的每一种，都与适合于操作它们的,方法集相关联,我们想对我们创建的数据,类型做同样的事情。

麻省理工公开课 - 计算机科学及编程导论课程节选