有没有办法一类以“删除”，该公司已经继承的方法？ [英] Is there way for a class to 'remove' methods that it has inherited?

问题描述

有没有办法一类以删除，它继承了方法呢？

例如。如果我不希望我的班有一个的ToString（）方法我可以做一些事情，使其不再可用？

解决方案

没有 - 这将违反里氏的替换原则。你应该总是能够使用一个亚型的实例，就好像它是一个超类的一个实例。

不要忘了，来电者可能只知道你的键入为基类型或接口。考虑下面的代码：

 对象foo =新TypeWithToStringRemoved（）; 
 foo.ToString（）; 
  

这不得不编译，不是吗？现在，你会期望在执行时会发生什么？

现在的的ToString ，的GetHashCode ，等于和的GetType 有没有办法避免让他们摆在首位 - 但通常，如果有你想从基本类型为删除的方法，即意味着你不应该从它继承摆在首位。我个人觉得传承的作用，面向对象的编程是有点夸大了：它是非常有用的它的真正的有用的，但一般来说，我更喜欢继承组成和接口作为抽象的形式，而不是基类<。 / p>

Is there way for a class to 'remove' methods that it has inherited?

E.g. if I don't want my class to have a ToString() method can I do something so that it is no longer available?

解决方案

No - this would violate Liskov's Substitution Principle. You should always be able to use an instance of a subtype as if it were an instance of a supertype.

Don't forget that a caller may only be aware of your type "as" the base type or an interface. Consider this code:

object foo = new TypeWithToStringRemoved();
foo.ToString();

That would have to compile, wouldn't it? Now what would you expect to happen at execution time?

Now for ToString, GetHashCode, Equals and GetType there's no way to avoid having them in the first place - but usually if there are methods you want to "remove" from a base type, that suggests you shouldn't be inheriting from it in the first place. Personally I find the role of inheritance is somewhat overplayed in object oriented programming: where it's useful it's really useful, but generally I prefer composition over inheritance, and interfaces as a form of abstraction rather than base classes.

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