为什么GetHash code是在Object类？

问题描述

为什么 GetHash code 是Object类的一部分？的类中的对象的唯一小部分被用来作为哈希表中的键。那岂不是更好有必须实现一个单独的接口，当我们想要的类的对象作为哈希表键。

Why GetHashCode is part of the Object class? Only small part of the objects of the classes are used as keys in hash tables. Wouldn't it be better to have a separate interface which must be implemented when we want objects of the class to serve as keys in hash table.

必须有一个原因，MS团队决定将这一方法在Object类中，从而使其可无处不在。

There must be a reason that MS team decided to include this method in Object class and thus make it available "everywhere".

推荐答案

这是一个设计错误，从Java拷贝，海事组织。

It was a design mistake copied from Java, IMO.

在我的完美的世界：

• 的ToString 将改名 ToDebugString 来设置适当的期望
• 等于和 GetHash code 将消失
• 将有一个 ReferenceEqualityComparer 实施的IEqualityComparer＆LT的; T＆GT; ：将等于这部分是很容易的一会儿，但没有办法得到一个原始的散列code，如果它的覆盖的
• 在对象不会有与之关联的监视器：显示器将有一个构造，而输入 / 退出等将是实例方法。

• ToString would be renamed ToDebugString to set expectations appropriately
• Equals and GetHashCode would be gone
• There would be a ReferenceEqualityComparer implementation of IEqualityComparer<T>: the equals part of this is easy at the moment, but there's no way of getting an "original" hash code if it's overridden
• Objects wouldn't have monitors associated with them: Monitor would have a constructor, and Enter/Exit etc would be instance methods.

平等（和哈希）在一般的继承层次原因的问题 - 只要你总是可以指定一种比较要使用（通过的IEqualityComparer＆LT; T＆GT; ）和对象可以实现 IEquatable＆LT; T＆GT; 自己，如果他们想，我不明白为什么这应该是对象。 EqualityComparer＆LT; T＆GT; .DEFAULT 可以使用的参考实现，如果 T 未实施 IEquatable＆LT ; T＆GT; ，并推迟到对象除外。生活是令人愉快的。

Equality (and thus hashing) cause problems in inheritance hierarchies in general - so long as you can always specify the kind of comparison you want to use (via IEqualityComparer<T>) and objects can implement IEquatable<T> themselves if they want to, I don't see why it should be on Object. EqualityComparer<T>.Default could use the reference implementation if T didn't implement IEquatable<T> and defer to the objects otherwise. Life would be pleasant.

不错啊。虽然我在这，数组协变是另一个平台上的错误。如果你想在C＃语言的错误，我可以启动另一个次要的言论，如果你喜欢。）（这还是迄今为止我最喜欢的语言，但有件事情我想一直做不同的）

Ah well. While I'm at it, array covariance was another platform mistake. If you want language mistakes in C#, I can start another minor rant if you like ;) (It's still by far my favourite language, but there are things I wish had been done differently.)

我已经博客这个的其他地方，顺便说一句。

I've blogged about this elsewhere, btw.

这篇关于为什么GetHash code是在Object类？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！