c# - 枚举扩展方法未显示

Question

我正在尝试为枚举添加新的/扩展方法，但扩展方法未显示在智能感知方法列表中。请帮助这是我的代码。

扩展名:

public static class EnumExtensions
    {
        public static string GetDescriptionAttr(this Enum value,string key)
        {
            var type = value.GetType();
            var memInfo = type.GetMember(key);
            var attributes = memInfo[0].GetCustomAttributes(typeof(DescriptionAttribute),
                false);
            var description = ((DescriptionAttribute)attributes[0]).Description;
            return description;
        }
    }

试图调用其他类的结果(调用者和扩展都在同一个项目中)

Answer 1

扩展方法只能应用于实例

public static class EnumExtensions {
  // This extension method requires "value" argument
  // that should be an instance of Enum class 
  public static string GetDescriptionAttr(this Enum value, string key) {
    ...
  }
}

...

public enum MyEnum {
  One, 
  Two,
  Three
}

Enum myEnum = MyEnum.One;

// You can call extension method on instance (myEnum) only
myEnum.GetDescriptionAttr("One");