我的枚举由以下值组成:
private enum PublishStatusses{
NotCompleted,
Completed,
Error
};
我希望能够以用户友好的方式输出这些值。 我不需要再从字符串到值。
当前回答
我碰巧是个VB。这是我的版本，结合了DescriptionAttribute方法和扩展方法。一、研究结果:
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
基本内容:一个名为EnumType的枚举，有三个值V1, V2和V3。“魔法”发生在控制台。在Sub Main()中调用WriteLine，其中最后一个参数只是v.Description。它为V1返回“1”，为V2返回“V2”，为V3返回“3”。这个description方法实际上是一个扩展方法，定义在另一个名为EnumExtensions的模块中:
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，所以查找也缓存在一个私有Dictionary中，该Dictionary是按需填充的。
(对不起，VB。NET解决方案-将其转换为c#应该相对简单，而我的c#在扩展等新主题上已经生疏了)
其他回答
public enum MyEnum
{
[Description("Option One")]
Option_One
}
public static string ToDescriptionString(this Enum This)
{
Type type = This.GetType();
string name = Enum.GetName(type, This);
MemberInfo member = type.GetMembers()
.Where(w => w.Name == name)
.FirstOrDefault();
DescriptionAttribute attribute = member != null
? member.GetCustomAttributes(true)
.Where(w => w.GetType() == typeof(DescriptionAttribute))
.FirstOrDefault() as DescriptionAttribute
: null;
return attribute != null ? attribute.Description : name;
}
这是对Ray Booysen的代码的更新，使用通用的GetCustomAttributes方法和LINQ使事情变得更整洁。
/// <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 http://stackoverflow.com/questions/479410/enum-tostring/479417#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();
}
我已经迟到7年了:-)但我相信这个话题经常被访问。所以我想在咖啡里加一点糖:
那么“F”格式字符串说明符呢?
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。 在将变量赋值给字符串的情况下，ToString()执行以下工作:
string foo = PublishStatusses.Error.ToString(); // or ToString("F")
如果它要在CamelCase字符串的单词之间插入空格，你可以使用正则表达式:
Regex.Replace(foo, "(\\B[A-Z])", " $1")
其他一些避免类/引用类型的更基本的选项:
数组的方法 嵌套结构方法
数组的方法
private struct PublishStatusses
{
public static string[] Desc = {
"Not Completed",
"Completed",
"Error"
};
public enum Id
{
NotCompleted = 0,
Completed,
Error
};
}
使用
string desc = PublishStatusses.Desc[(int)PublishStatusses.Id.Completed];
嵌套结构方法
private struct PublishStatusses
{
public struct NotCompleted
{
public const int Id = 0;
public const string Desc = "Not Completed";
}
public struct Completed
{
public const int Id = 1;
public const string Desc = "Completed";
}
public struct Error
{
public const int Id = 2;
public const string Desc = "Error";
}
}
使用
int id = PublishStatusses.NotCompleted.Id;
string desc = PublishStatusses.NotCompleted.Desc;
更新(03/09/2018)
扩展方法和上面第一种技术的混合。
我更喜欢将枚举定义在它们“所属”的位置(最接近它们的起源源，而不是某个通用的全局名称空间)。
namespace ViewModels
{
public class RecordVM
{
//public enum Enum { Minutes, Hours }
public struct Enum
{
public enum Id { Minutes, Hours }
public static string[] Name = { "Minute(s)", "Hour(s)" };
}
}
}
扩展方法似乎适合于公共区域，枚举的“本地化”定义现在使扩展方法更加详细。
namespace Common
{
public static class EnumExtensions
{
public static string Name(this RecordVM.Enum.Id id)
{
return RecordVM.Enum.Name[(int)id];
}
}
}
枚举及其扩展方法的使用示例。
namespace Views
{
public class RecordView
{
private RecordDataFieldList<string, string> _fieldUnit;
public RecordView()
{
_fieldUnit.List = new IdValueList<string, string>
{
new ListItem<string>((int)RecordVM.Enum.Id.Minutes, RecordVM.Enum.Id.Minutes.Name()),
new ListItem<string>((int)RecordVM.Enum.Id.Hours, RecordVM.Enum.Id.Hours.Name())
};
}
private void Update()
{
RecordVM.Enum.Id eId = DetermineUnit();
_fieldUnit.Input.Text = _fieldUnit.List.SetSelected((int)eId).Value;
}
}
}
注意:我实际上决定消除Enum包装器(和Name数组)，因为名称字符串最好来自资源(即配置文件或DB)而不是硬编码，并且因为我最终将扩展方法放在ViewModels名称空间中(只是在不同的“CommonVM.cs”文件中)。此外，整个。id的事情变得令人分心和麻烦。
namespace ViewModels
{
public class RecordVM
{
public enum Enum { Minutes, Hours }
//public struct Enum
//{
// public enum Id { Minutes, Hours }
// public static string[] Name = { "Minute(s)", "Hour(s)" };
//}
}
}
CommonVM.cs
//namespace Common
namespace ViewModels
{
public static class EnumExtensions
{
public static string Name(this RecordVM.Enum id)
{
//return RecordVM.Enum.Name[(int)id];
switch (id)
{
case RecordVM.Enum.Minutes: return "Minute(s)";
case RecordVM.Enum.Hours: return "Hour(s)";
default: return null;
}
}
}
}
枚举及其扩展方法的使用示例。
namespace Views
{
public class RecordView
{
private RecordDataFieldList<string, string> _fieldUnit
public RecordView()
{
_fieldUnit.List = new IdValueList<string, string>
{
new ListItem<string>((int)RecordVM.Enum.Id.Minutes, RecordVM.Enum.Id.Minutes.Name()),
new ListItem<string>((int)RecordVM.Enum.Id.Hours, RecordVM.Enum.Id.Hours.Name())
};
}
private void Update()
{
RecordVM.Enum eId = DetermineUnit();
_fieldUnit.Input.Text = _fieldUnit.List.SetSelected((int)eId).Value;
}
}
}
如果您只是想在单词之间添加空格，那么简单到
string res = Regex.Replace(PublishStatusses.NotCompleted, "[A-Z]", " $0").Trim();
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