如何向枚举添加扩展方法 [英] How to add extension methods to Enums

问题描述

我有这个枚举代码:

enum Duration { Day, Week, Month };

我可以为此 Enum 添加扩展方法吗?

Can I add a extension methods for this Enum?

推荐答案

根据这个 网站:

扩展方法提供了一种为现有类编写方法的方法，您团队中的其他人可能会实际发现和使用这种方法.鉴于枚举和其他任何类一样，您可以扩展它们也就不足为奇了，例如:

Extension methods provide a way to write methods for existing classes in a way other people on your team might actually discover and use. Given that enums are classes like any other it shouldn’t be too surprising that you can extend them, like:

enum Duration { Day, Week, Month };

static class DurationExtensions 
{
  public static DateTime From(this Duration duration, DateTime dateTime) 
  {
    switch (duration) 
    {
      case Day:   return dateTime.AddDays(1);
      case Week:  return dateTime.AddDays(7);
      case Month: return dateTime.AddMonths(1);
      default:    throw new ArgumentOutOfRangeException("duration");
    }
  }
}

我认为枚举通常不是最佳选择，但至少这可以让您集中一些 switch/if 处理并将它们抽象一点，直到您可以做更好的事情.请记住检查值是否也在范围内.

I think enums are not the best choice in general but at least this lets you centralize some of the switch/if handling and abstract them away a bit until you can do something better. Remember to check the values are in range too.

您可以在 Microsft MSDN 此处阅读更多信息.

You can read more here at Microsft MSDN.

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