我可以将继承与扩展方法一起使用吗? [英] Can I use inheritance with an extension method?

问题描述

我有以下内容:

public static class CityStatusExt
{
    public static string D2(this CityStatus key)
    {
        return ((int) key).ToString("D2");
    }


public static class CityTypeExt
{
    public static string D2(this CityType key)
    {
        return ((int) key).ToString("D2");
    }

加上其他具有类似扩展名的类，这些类返回格式为"D2"的键

Plus other classes with similar extensions that return the key formatted as a "D2"

有没有一种方法可以从基类继承并让基类提供功能，因此我不必重复相同的扩展方法代码吗?

Is there a way I could inherit from a base class and have the base class provide the functionality so don't I don't have to repeat the same extension method code?

更新.很抱歉，我没有提到这一点，但是类似CityType的类是Enums.

Update. I am sorry I did not mention this but my classes like CityType are Enums.

推荐答案

从下面的注释中， CityType 和 CityStatus 是枚举.因此，您可以执行以下操作:

From the comment below, CityType and CityStatus are enums. Therefore you can do this:

public static class Extensions
{
    public static string D2(this Enum key)
    {
        return Convert.ToInt32(key).ToString("D2");
    }
}

---

原始答案:

---

Original answer:

您可以使用通用方法和接口 ID2Able :

You can use a generic method and an interface ID2Able:

public static class Extensions
{ 
    public static string D2<T>(this T key) where T : ID2Able
    { 
        return ((int) key).ToString("D2"); 
    } 
}

这样，扩展方法就不会对每种类型都显示出来；它仅适用于您从中继承 ID2Able 的事物.

This way the extension method won't show up for absolutely every type; it'll only be available for things you inherit ID2Able from.

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