枚举的 ToString 方法如何返回易于理解的字符串？

不要使用枚举，而是使用静态类。

替换

private enum PublishStatuses{
    NotCompleted,
    Completed,
    Error
};

使用

private static class PublishStatuses{
    public static readonly string NotCompleted = "Not Completed";
    public static readonly string Completed = "Completed";
    public static readonly string Error = "Error";
};

它将被这样使用

PublishStatuses.NotCompleted; // "Not Completed"

使用“扩展方法”解决方案时出现问题：

私有枚举通常在另一个类内部使用。扩展方法解决方案在此处无效，因为它必须在自己的类中。这个解决方案可以是私有的，并嵌入到另一个类中。

关于Ray Booysen的问题，代码存在一个错误：枚举类型 ToString 方法的用户友好字符串。
您需要考虑枚举值上的多个属性。

public static string GetDescription<T>(this object enumerationValue)
            where T : struct
    {
        Type type = enumerationValue.GetType();
        if (!type.IsEnum)
        {
            throw new ArgumentException("EnumerationValue must be of Enum type", "enumerationValue");
        }

        //Tries to find a DescriptionAttribute for a potential friendly name
        //for the enum
        MemberInfo[] memberInfo = type.GetMember(enumerationValue.ToString());
        if (memberInfo != null && memberInfo.Length > 0)
        {
            object[] attrs = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);

            if (attrs != null && attrs.Length > 0 && attrs.Where(t => t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault() != null)
            {
                //Pull out the description value
                return ((DescriptionAttribute)attrs.Where(t=>t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault()).Description;
            }
        }
        //If we have no description attribute, just return the ToString of the enum
        return enumerationValue.ToString();

以下是建议摘要和示例：

namespace EnumExtensions {

using System;
using System.Reflection;

public class TextAttribute : Attribute {
   public string Text;
   public TextAttribute( string text ) {
      Text = text;
   }//ctor
}// class TextAttribute

public static class EnumExtender {

public static string ToText( this Enum enumeration ) {

   MemberInfo[] memberInfo = enumeration.GetType().GetMember( enumeration.ToString() );

   if ( memberInfo != null && memberInfo.Length > 0 ) {

      object[] attributes = memberInfo[ 0 ].GetCustomAttributes( typeof(TextAttribute),  false );

      if ( attributes != null && attributes.Length > 0 ) {
         return ( (TextAttribute)attributes[ 0 ] ).Text;
      }

   }//if

   return enumeration.ToString();

}//ToText

}//class EnumExtender

}//namespace

使用方法：

using System;
using EnumExtensions;

class Program {

public enum Appearance {

  [Text( "left-handed" ) ]
  Left,

  [Text( "right-handed" ) ]
  Right,

}//enum

static void Main( string[] args ) {

   var appearance = Appearance.Left;
   Console.WriteLine( appearance.ToText() );

}//Main

}//class

我晚了7年才参加这个派对 :-) 但我相信这个主题经常被访问。
所以，我想给咖啡加点糖：

那么，“F”格式字符串指示符呢？

PublishStatusses[] ps = Enum.GetValues<PublishStatusses>();
ps.ToList().ForEach(c => Console.Write($"{c:F} "));

不需要任何显式的函数调用。

事实上，甚至不需要任何格式说明符。 如果将变量赋值给字符串，在ToString()函数中完成工作：

string foo = PublishStatusses.Error.ToString(); // or ToString("F")

如果要在CamelCase字符串中单词之间插入空格，您可以使用正则表达式：

Regex.Replace(foo, "(\\B[A-Z])", " $1")

我恰巧是VB.NET的粉丝，下面是我的版本，结合了DescriptionAttribute方法和扩展方法。首先，这是结果：

Imports System.ComponentModel ' For <Description>

Module Module1
  ''' <summary>
  ''' An Enum type with three values and descriptions
  ''' </summary>
  Public Enum EnumType
    <Description("One")>
    V1 = 1

    ' This one has no description
    V2 = 2

    <Description("Three")>
    V3 = 3
  End Enum

  Sub Main()
    ' Description method is an extension in EnumExtensions
    For Each v As EnumType In [Enum].GetValues(GetType(EnumType))
      Console.WriteLine("Enum {0} has value {1} and description {2}",
        v,
        CInt(v),
        v.Description
      )
    Next
    ' Output:
    ' Enum V1 has value 1 and description One
    ' Enum V2 has value 2 and description V2
    ' Enum V3 has value 3 and description Three
  End Sub
End Module

基础内容：一个名为EnumType的枚举，包括三个值V1、V2和V3。在Sub Main ()中，通过Console.WriteLine调用时，最后一个参数是简单的v.Description。对于V1，返回“One”，对于V2，则返回“V2”，对于V3，则返回“Three”。实际上，这个Description方法是一个扩展方法，在另一个叫做EnumExtensions的模块中定义：

Option Strict On
Option Explicit On
Option Infer Off

Imports System.Runtime.CompilerServices
Imports System.Reflection
Imports System.ComponentModel

Module EnumExtensions
  Private _Descriptions As New Dictionary(Of String, String)

  ''' <summary>
  ''' This extension method adds a Description method
  ''' to all enum members. The result of the method is the
  ''' value of the Description attribute if present, else
  ''' the normal ToString() representation of the enum value.
  ''' </summary>
  <Extension>
  Public Function Description(e As [Enum]) As String
    ' Get the type of the enum
    Dim enumType As Type = e.GetType()
    ' Get the name of the enum value
    Dim name As String = e.ToString()

    ' Construct a full name for this enum value
    Dim fullName As String = enumType.FullName + "." + name

    ' See if we have looked it up earlier
    Dim enumDescription As String = Nothing
    If _Descriptions.TryGetValue(fullName, enumDescription) Then
      ' Yes we have - return previous value
      Return enumDescription
    End If

    ' Find the value of the Description attribute on this enum value
    Dim members As MemberInfo() = enumType.GetMember(name)
    If members IsNot Nothing AndAlso members.Length > 0 Then
      Dim descriptions() As Object = members(0).GetCustomAttributes(GetType(DescriptionAttribute), False)
      If descriptions IsNot Nothing AndAlso descriptions.Length > 0 Then
        ' Set name to description found
        name = DirectCast(descriptions(0), DescriptionAttribute).Description
      End If
    End If

    ' Save the name in the dictionary:
    _Descriptions.Add(fullName, name)

    ' Return the name
    Return name
  End Function
End Module

因为使用 Reflection 查找描述属性很慢，所以这些查找也会缓存在一个私有 Dictionary 中，该字典在需要时填充。
（抱歉提供的是 VB.NET 解决方案 - 将其翻译成 C# 应该相对简单，而且我的 C# 在新主题（如扩展）上有点生疏）

更加简洁的概述：

using System;
using System.Reflection;

public class TextAttribute : Attribute
{
    public string Text;
    public TextAttribute(string text)
    {
        Text = text;
    }
}  

public static class EnumExtender
{
    public static string ToText(this Enum enumeration)
    {
        var memberInfo = enumeration.GetType().GetMember(enumeration.ToString());
        if (memberInfo.Length <= 0) return enumeration.ToString();

        var attributes = memberInfo[0].GetCustomAttributes(typeof(TextAttribute), false);
        return attributes.Length > 0 ? ((TextAttribute)attributes[0]).Text : enumeration.ToString();
    }
}

与underscore描述的用法相同。

使用 Enum.GetName

从上面的链接中...

using System;

public class GetNameTest {
    enum Colors { Red, Green, Blue, Yellow };
    enum Styles { Plaid, Striped, Tartan, Corduroy };

    public static void Main() {

        Console.WriteLine("The 4th value of the Colors Enum is {0}", Enum.GetName(typeof(Colors), 3));
        Console.WriteLine("The 4th value of the Styles Enum is {0}", Enum.GetName(typeof(Styles), 3));
    }
}
// The example displays the following output:
//       The 4th value of the Colors Enum is Yellow
//       The 4th value of the Styles Enum is Corduroy

根据这份文档：https://learn.microsoft.com/pt-br/dotnet/api/system.enum.tostring?view=netframework-4.8，可以使用类似以下的格式将枚举器转换为字符串：

public enum Example
{
    Example1,
    Example2
}

Console.WriteLine(Example.Example1.ToString("g"));

//Outputs: "Example1"

您可以在此链接中查看所有可能的格式：https://learn.microsoft.com/pt-br/dotnet/api/system.string?view=netframework-4.8。

如果你无论如何都使用Newtonsoft，你可以按照以下方式进行操作：

// Enum

[Newtonsoft.Json.JsonConverter(typeof(StringEnumConverter))]
public enum MyEnum
{
   [EnumMember(Value = "User friendly value")]
   SomeValue=0,
}

// Usage as extension method

public static string ToDefaultString(this Enum enumValue)
{
   return JsonConvert.SerializeObject(enumValue).Replace("\"", "");
}

这是对Ray Booysen代码的更新，它使用通用的GetCustomAttributes方法和LINQ使事情变得更加整洁。

    /// <summary>
    /// Gets the value of the <see cref="T:System.ComponentModel.DescriptionAttribute"/> on an struct, including enums.  
    /// </summary>
    /// <typeparam name="T">The type of the struct.</typeparam>
    /// <param name="enumerationValue">A value of type <see cref="T:System.Enum"/></param>
    /// <returns>If the struct has a Description attribute, this method returns the description.  Otherwise it just calls ToString() on the struct.</returns>
    /// <remarks>Based on https://dev59.com/knRB5IYBdhLWcg3w4bEo#479417, but useful for any struct.</remarks>
    public static string GetDescription<T>(this T enumerationValue) where T : struct
    {
        return enumerationValue.GetType().GetMember(enumerationValue.ToString())
                .SelectMany(mi => mi.GetCustomAttributes<DescriptionAttribute>(false),
                    (mi, ca) => ca.Description)
                .FirstOrDefault() ?? enumerationValue.ToString();
    }