And that's a wonderful thing to have because it gives you that modularity, that encapsulation that basically says, when I create a point, the only way I can get at the values, is by using one of the defined methods, in this case it could be Cartesian, Cartesian and get all the pieces of that.

这是很棒的一件事情,因为它让你有了，模块性以及封装性，这基本上也就是说，当我创建了一个点，我能够得到它的值的唯一的方式，就是用一个定义好的方法，在这个例子中也就是。

麻省理工公开课 - 计算机科学及编程导论课程节选