有没有在C＃中的任何方式来覆盖类的方法，扩展方法？ [英] Is there any way in C# to override a class method with an extension method?

问题描述

有过几次在那里我会想覆盖类中的方法，扩展方法。有没有办法做到这一点在C＃？

There have been occasions where I would want to override a method in a class with an extension method. Is there any way to do that in C#?

例如：

public static class StringExtension
{
    public static int GetHashCode(this string inStr)
    {
        return MyHash(inStr);
    }
}

在这里，我想这方面的一个例子是，能够为一个字符串的哈希存储到数据库中，并有相同的值由所有使用String类的哈希值（即词典等类中使用）由于内置的​​.Net散列算法不能保证是从框架到下一个版本兼容，我想用我自己来取代它。

A case where I've wanted to do this is to be able to store a hash of a string into a database and have that same value be used by all the classes that use the string class's hash (i.e. Dictionary, etc.) Since the built-in .Net hashing algorithm is not guaranteed to be compatible from one version of the Framework to the next, I want to replace it with my own.

有其他情况我碰到，我会想重写一个类方法，扩展方法以及因此它不只是特定的字符串类或GetHash code方法。

There are other case I've run into where I'd want to override a class method with an extension method as well so it's not just specific to the string class or the GetHashCode method.

我知道我可以与继承了现有的类做到这一点，但它会很方便，能够在很多情况下，一个扩展做到这一点。

I know I could do this with subclassing off an existing class but it would be handy to be able to do it with an extension in a lot of cases.

推荐答案

没有;扩展方法从来没有一个合适的签名优先级高于一个实例方法，从不参与多态性（ GetHash code 是虚拟法）。

No; an extension method never takes priority over an instance method with a suitable signature, and never participates in polymorphism (GetHashCode is a virtual method).

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