如何从两个类继承 [英] How to inherit from two classes

问题描述

我有一个People类，以及从其继承的Student和Employee类.但是如果我有一个既是Student又是Employee ...

I have a People class, and Student and Employee classes which inherit from it. But if I have a person who is both a Student and an Employee...

...您将如何实现这一目标?

... How would you go about implementing this?

推荐答案

这是对问题域进行了不正确分析的经典示例.是的，在某些情况下，将学生"视为人"类型，将雇员"视为人"类型可能是适当的，但是-根据您的问题领域-也可能不合适

That's a classic example of an improperly analyzed problem domain. Yes, in some situations, it may be proper to think of "Student" as a type of "Person" and an "Employee" as a type of "Person", but - depending on your problem domain - it may also not be appropriate.

如果您的域要求某人既是学生"又是雇员"，则应考虑问题域中学生"和人"之间的关系是否确实是"is-a"的关系.

If your domain requires that something be both a "Student" and an "Employee", you should consider if the relation between "Student" and "Person" in your problem domain is really an "is-a" relationship.

在这种特殊情况下，成为一名学生可能只是特定人的属性.因此，John Doe是一个人，可能还拥有学生"的当前职业".在这种情况下，他可能会列出几个当前职业".这样的世界中的关系就变成了有一个"而不是是一个".因此，学生"和员工"成为职业"的子类.

It could be that in this particular case, being a student is merely an attribute of a particular person. So, John Doe is a person, who may also have a "current occupation" of "Student". In this case, he may have a list of several "current occupations". And the relationship in such a world becomes "has-a" rather than "is-a". So "Student" and "Employee" become subclasses of "Occupation".

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