枚举的扩展方法，而不是枚举的实例 [英] Extension method on enumeration, not instance of enumeration

问题描述

  public enum Things 
 {
 OneThing ，
 AnotherThing 
} 
  

我想为此编写一个扩展方法枚举（类似于这里的奖项答案），但是该方法适用于枚举的实例，ala

 <$事物东西var list = thing.ToSelectList（）; 
  

我希望它可以在实际枚举上工作： p>

  var list = Things.ToSelectList（）; 
  

我可以做

  var list = default（Things）.ToSelectList（）; 
  

但是我不喜欢那个样子:)

我已经使用以下扩展方法更接近：

  public static SelectList ToSelectList（this Type type）
 {
 if（type.IsEnum）
 {
 var values =从Enum.GetValues（类型）中的枚举e 
选择新的{ID = e，Name = e .ToString（）}; 
返回新的SelectList（值，Id，Name）; 
} 
 else 
 {
返回null; 
} 
} 
  

像这样使用：

  var list = typeof（Things）.ToSelectList（）; 
  

我们可以做得更好吗？

  public class SelectList 
 {
 // Normal SelectList properties / methods go here 
 
 public static SelectList Of< T>（）
 {
类型t = typeof（T）; 
 if（t.IsEnum）
 {
 var values =从Enum.GetValues（类型）中的枚举e 
 select new {ID = e，Name = e.ToString（） }; 
返回新的SelectList（值，Id，Name）; 
} 
返回null; 
} 
} 
  

然后你可以得到这样的选择列表： / p>

  var list = SelectList.Of< Things>（）; 
  

IMO读取比 Things.ToSelectList（）。

I have an enumeration for my Things like so:

public enum Things
{
   OneThing,
   AnotherThing
}

I would like to write an extension method for this enumeration (similar to Prise's answer here) but while that method works on an instance of the enumeration, ala

Things thing; var list = thing.ToSelectList();

I would like it to work on the actual enumeration instead:

var list = Things.ToSelectList();

I could just do

var list = default(Things).ToSelectList();

But I don't like the look of that :)

I have gotten closer with the following extension method:

public static SelectList ToSelectList(this Type type)
{
   if (type.IsEnum)
   {
      var values = from Enum e in Enum.GetValues(type)
                   select new { ID = e, Name = e.ToString() };
      return new SelectList(values, "Id", "Name");
   }
   else
   {
      return null;
   }
}

Used like so:

var list = typeof(Things).ToSelectList();

Can we do any better than that?

解决方案

Extension methods only work on instances, so it can't be done, but with some well-chosen class/method names and generics, you can produce a result that looks just as good:

public class SelectList
{
    // Normal SelectList properties/methods go here

    public static SelectList Of<T>()
    {
        Type t = typeof(T);
        if (t.IsEnum)
        {
            var values = from Enum e in Enum.GetValues(type)
                         select new { ID = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name");
        }
        return null;
    }
}

Then you can get your select list like this:

var list = SelectList.Of<Things>();

IMO this reads a lot better than Things.ToSelectList().

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