Answers:
有一个解决方案。考虑以下:
public sealed class AccountStatus
{
public static readonly AccountStatus Open = new AccountStatus(1);
public static readonly AccountStatus Closed = new AccountStatus(2);
public static readonly SortedList<byte, AccountStatus> Values = new SortedList<byte, AccountStatus>();
private readonly byte Value;
private AccountStatus(byte value)
{
this.Value = value;
Values.Add(value, this);
}
public static implicit operator AccountStatus(byte value)
{
return Values[value];
}
public static implicit operator byte(AccountStatus value)
{
return value.Value;
}
}
上面提供了隐式转换:
AccountStatus openedAccount = 1; // Works
byte openedValue = AccountStatus.Open; // Works
这比声明一个普通的枚举要花更多的功夫(尽管您可以将上述内容重构为一个通用的通用基类)。通过使基类实现IComparable和IEquatable,以及添加方法以返回DescriptionAttributes的值,声明的名称等,您可以走得更远。
我编写了一个基类(RichEnum <>)来处理大多数艰苦的工作,这使上面的枚举声明简化为:
public sealed class AccountStatus : RichEnum<byte, AccountStatus>
{
public static readonly AccountStatus Open = new AccountStatus(1);
public static readonly AccountStatus Closed = new AccountStatus(2);
private AccountStatus(byte value) : base (value)
{
}
public static implicit operator AccountStatus(byte value)
{
return Convert(value);
}
}
下面列出了基类(RichEnum)。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
using System.Resources;
namespace Ethica
{
using Reflection;
using Text;
[DebuggerDisplay("{Value} ({Name})")]
public abstract class RichEnum<TValue, TDerived>
: IEquatable<TDerived>,
IComparable<TDerived>,
IComparable, IComparer<TDerived>
where TValue : struct , IComparable<TValue>, IEquatable<TValue>
where TDerived : RichEnum<TValue, TDerived>
{
#region Backing Fields
/// <summary>
/// The value of the enum item
/// </summary>
public readonly TValue Value;
/// <summary>
/// The public field name, determined from reflection
/// </summary>
private string _name;
/// <summary>
/// The DescriptionAttribute, if any, linked to the declaring field
/// </summary>
private DescriptionAttribute _descriptionAttribute;
/// <summary>
/// Reverse lookup to convert values back to local instances
/// </summary>
private static SortedList<TValue, TDerived> _values;
private static bool _isInitialized;
#endregion
#region Constructors
protected RichEnum(TValue value)
{
if (_values == null)
_values = new SortedList<TValue, TDerived>();
this.Value = value;
_values.Add(value, (TDerived)this);
}
#endregion
#region Properties
public string Name
{
get
{
CheckInitialized();
return _name;
}
}
public string Description
{
get
{
CheckInitialized();
if (_descriptionAttribute != null)
return _descriptionAttribute.Description;
return _name;
}
}
#endregion
#region Initialization
private static void CheckInitialized()
{
if (!_isInitialized)
{
ResourceManager _resources = new ResourceManager(typeof(TDerived).Name, typeof(TDerived).Assembly);
var fields = typeof(TDerived)
.GetFields(BindingFlags.Static | BindingFlags.GetField | BindingFlags.Public)
.Where(t => t.FieldType == typeof(TDerived));
foreach (var field in fields)
{
TDerived instance = (TDerived)field.GetValue(null);
instance._name = field.Name;
instance._descriptionAttribute = field.GetAttribute<DescriptionAttribute>();
var displayName = field.Name.ToPhrase();
}
_isInitialized = true;
}
}
#endregion
#region Conversion and Equality
public static TDerived Convert(TValue value)
{
return _values[value];
}
public static bool TryConvert(TValue value, out TDerived result)
{
return _values.TryGetValue(value, out result);
}
public static implicit operator TValue(RichEnum<TValue, TDerived> value)
{
return value.Value;
}
public static implicit operator RichEnum<TValue, TDerived>(TValue value)
{
return _values[value];
}
public static implicit operator TDerived(RichEnum<TValue, TDerived> value)
{
return value;
}
public override string ToString()
{
return _name;
}
#endregion
#region IEquatable<TDerived> Members
public override bool Equals(object obj)
{
if (obj != null)
{
if (obj is TValue)
return Value.Equals((TValue)obj);
if (obj is TDerived)
return Value.Equals(((TDerived)obj).Value);
}
return false;
}
bool IEquatable<TDerived>.Equals(TDerived other)
{
return Value.Equals(other.Value);
}
public override int GetHashCode()
{
return Value.GetHashCode();
}
#endregion
#region IComparable Members
int IComparable<TDerived>.CompareTo(TDerived other)
{
return Value.CompareTo(other.Value);
}
int IComparable.CompareTo(object obj)
{
if (obj != null)
{
if (obj is TValue)
return Value.CompareTo((TValue)obj);
if (obj is TDerived)
return Value.CompareTo(((TDerived)obj).Value);
}
return -1;
}
int IComparer<TDerived>.Compare(TDerived x, TDerived y)
{
return (x == null) ? -1 :
(y == null) ? 1 :
x.Value.CompareTo(y.Value);
}
#endregion
public static IEnumerable<TDerived> Values
{
get
{
return _values.Values;
}
}
public static TDerived Parse(string name)
{
foreach (TDerived value in _values.Values)
if (0 == string.Compare(value.Name, name, true) || 0 == string.Compare(value.DisplayName, name, true))
return value;
return null;
}
}
}
您不能进行隐式转换(零除外),也不能编写自己的实例方法-但是,您可能可以编写自己的扩展方法:
public enum MyEnum { A, B, C }
public static class MyEnumExt
{
public static int Value(this MyEnum foo) { return (int)foo; }
static void Main()
{
MyEnum val = MyEnum.A;
int i = val.Value();
}
}
但是,这并不能给您带来太多好处(与仅进行显式转换相比)。
我见过人们希望这样做的主要时间之一是[Flags]
通过泛型(即bool IsFlagSet<T>(T value, T flag);
方法)进行操作。不幸的是,C#3.0不支持泛型运算符,但是您可以使用this这样的方法来解决此问题,这使运算符可完全使用泛型。
struct PseudoEnum
{
public const int
INPT = 0,
CTXT = 1,
OUTP = 2;
};
// ...
var arr = new String[3];
arr[PseudoEnum.CTXT] = "can";
arr[PseudoEnum.INPT] = "use";
arr[PseudoEnum.CTXT] = "as";
arr[PseudoEnum.CTXT] = "array";
arr[PseudoEnum.OUTP] = "index";
static class
我想的。在最终IL
代码中争论两种情况都没有优势。
我改编了Mark出色的RichEnum通用基类。
定影
马克(Mark)出色的想法+实施的荣誉,给大家:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
using System.Resources;
namespace NMatrix
{
[DebuggerDisplay("{Value} ({Name})")]
public abstract class RichEnum<TValue, TDerived>
: IEquatable<TDerived>,
IComparable<TDerived>,
IComparable, IComparer<TDerived>
where TValue : struct, IComparable<TValue>, IEquatable<TValue>
where TDerived : RichEnum<TValue, TDerived>
{
#region Backing Fields
/// <summary>
/// The value of the enum item
/// </summary>
public readonly TValue Value;
/// <summary>
/// The public field name, determined from reflection
/// </summary>
private string _name;
/// <summary>
/// The DescriptionAttribute, if any, linked to the declaring field
/// </summary>
private DescriptionAttribute _descriptionAttribute;
/// <summary>
/// Reverse lookup to convert values back to local instances
/// </summary>
private static readonly SortedList<TValue, TDerived> _values = new SortedList<TValue, TDerived>();
#endregion
#region Constructors
protected RichEnum(TValue value)
{
this.Value = value;
_values.Add(value, (TDerived)this);
}
#endregion
#region Properties
public string Name
{
get
{
return _name;
}
}
public string Description
{
get
{
if (_descriptionAttribute != null)
return _descriptionAttribute.Description;
return _name;
}
}
#endregion
#region Initialization
static RichEnum()
{
var fields = typeof(TDerived)
.GetFields(BindingFlags.Static | BindingFlags.GetField | BindingFlags.Public)
.Where(t => t.FieldType == typeof(TDerived));
foreach (var field in fields)
{
/*var dummy =*/ field.GetValue(null); // forces static initializer to run for TDerived
TDerived instance = (TDerived)field.GetValue(null);
instance._name = field.Name;
instance._descriptionAttribute = field.GetCustomAttributes(true).OfType<DescriptionAttribute>().FirstOrDefault();
}
}
#endregion
#region Conversion and Equality
public static TDerived Convert(TValue value)
{
return _values[value];
}
public static bool TryConvert(TValue value, out TDerived result)
{
return _values.TryGetValue(value, out result);
}
public static implicit operator TValue(RichEnum<TValue, TDerived> value)
{
return value.Value;
}
public static implicit operator RichEnum<TValue, TDerived>(TValue value)
{
return _values[value];
}
public static implicit operator TDerived(RichEnum<TValue, TDerived> value)
{
return value;
}
public override string ToString()
{
return _name;
}
#endregion
#region IEquatable<TDerived> Members
public override bool Equals(object obj)
{
if (obj != null)
{
if (obj is TValue)
return Value.Equals((TValue)obj);
if (obj is TDerived)
return Value.Equals(((TDerived)obj).Value);
}
return false;
}
bool IEquatable<TDerived>.Equals(TDerived other)
{
return Value.Equals(other.Value);
}
public override int GetHashCode()
{
return Value.GetHashCode();
}
#endregion
#region IComparable Members
int IComparable<TDerived>.CompareTo(TDerived other)
{
return Value.CompareTo(other.Value);
}
int IComparable.CompareTo(object obj)
{
if (obj != null)
{
if (obj is TValue)
return Value.CompareTo((TValue)obj);
if (obj is TDerived)
return Value.CompareTo(((TDerived)obj).Value);
}
return -1;
}
int IComparer<TDerived>.Compare(TDerived x, TDerived y)
{
return (x == null) ? -1 :
(y == null) ? 1 :
x.Value.CompareTo(y.Value);
}
#endregion
public static IEnumerable<TDerived> Values
{
get
{
return _values.Values;
}
}
public static TDerived Parse(string name)
{
foreach (TDerived value in Values)
if (0 == string.Compare(value.Name, name, true))
return value;
return null;
}
}
}
我在mono上运行的用法示例:
using System.ComponentModel;
using System;
namespace NMatrix
{
public sealed class MyEnum : RichEnum<int, MyEnum>
{
[Description("aap")] public static readonly MyEnum my_aap = new MyEnum(63000);
[Description("noot")] public static readonly MyEnum my_noot = new MyEnum(63001);
[Description("mies")] public static readonly MyEnum my_mies = new MyEnum(63002);
private MyEnum(int value) : base (value) { }
public static implicit operator MyEnum(int value) { return Convert(value); }
}
public static class Program
{
public static void Main(string[] args)
{
foreach (var enumvalue in MyEnum.Values)
Console.WriteLine("MyEnum {0}: {1} ({2})", (int) enumvalue, enumvalue, enumvalue.Description);
}
}
}
产生输出
[mono] ~/custom/demo @ gmcs test.cs richenum.cs && ./test.exe
MyEnum 63000: my_aap (aap)
MyEnum 63001: my_noot (noot)
MyEnum 63002: my_mies (mies)
注意:单声道2.6.7需要额外的显式强制转换,而使用单声道2.8.2则不需要...
FirstOrDefault
,以避免假设只有一个属性)。当然,假设这样的事情是否是一个“好主意”(或坏的想法),取决于上下文
TDerived instance = (TDerived)field.GetValue(null);
结果instance
是null
。看来,Mono运行时必须具有与.NET相同的类型初始化顺序,以使它可以工作。令人费解!相反,我不得不将该代码移到静态方法中,并从子类的类型初始值设定项中调用它。
您无法对枚举类型声明隐式转换,因为它们无法定义方法。C#隐式关键字编译为以'op_'开头的方法,在这种情况下将不起作用。
如果将枚举的基数定义为long,则可以执行显式转换。我不知道您是否可以使用隐式转换,因为枚举不能在其上定义方法。
public enum MyEnum : long
{
one = 1,
two = 2,
}
MyEnum number = MyEnum.one;
long i = (long)number;
另外,请注意,未初始化的枚举将默认为0值或第一项-因此在上述情况下,最好也进行定义zero = 0
。
: long
这里;没有它,显式转换就可以正常工作。唯一合法的隐式转换为零。
枚举对我来说基本上没有用。
我最终总是做与图片相关的事情:
经典示例问题是用于检测按键的VirtualKey集。
enum VKeys : ushort
{
a = 1,
b = 2,
c = 3
}
// the goal is to index the array using predefined constants
int[] array = new int[500];
var x = array[VKeys.VK_LSHIFT];
这里的问题是您不能用枚举索引数组,因为它不能将枚举隐式转换为ushort(即使我们甚至将枚举基于ushort)
在此特定上下文中,以下数据结构淘汰了枚举。。。。
public static class VKeys
{
public const ushort
a = 1,
b = 2,
c = 3;
}
我已经解决了sehe答案的问题在MS .net(非Mono)上运行代码时,。对我来说,这个问题专门出现在.net 4.5.1上,但其他版本似乎也受到了影响。
访问public static TDervied MyEnumValue
由反射(通过FieldInfo.GetValue(null)
确实不初始化所述场。
无需TDerived
在静态初始值设定项上为实例分配名称,而是RichEnum<TValue, TDerived>
在第一次访问时懒惰地完成TDerived.Name
。代码:
public abstract class RichEnum<TValue, TDerived> : EquatableBase<TDerived>
where TValue : struct, IComparable<TValue>, IEquatable<TValue>
where TDerived : RichEnum<TValue, TDerived>
{
// Enforcing that the field Name (´SomeEnum.SomeEnumValue´) is the same as its
// instances ´SomeEnum.Name´ is done by the static initializer of this class.
// Explanation of initialization sequence:
// 1. the static initializer of ´RichEnum<TValue, TDerived>´ reflects TDervied and
// creates a list of all ´public static TDervied´ fields:
// ´EnumInstanceToNameMapping´
// 2. the static initializer of ´TDerive´d assigns values to these fields
// 3. The user is now able to access the values of a field.
// Upon first access of ´TDervied.Name´ we search the list
// ´EnumInstanceToNameMapping´ (created at step 1) for the field that holds
// ´this´ instance of ´TDerived´.
// We then get the Name for ´this´ from the FieldInfo
private static readonly IReadOnlyCollection<EnumInstanceReflectionInfo>
EnumInstanceToNameMapping =
typeof(TDerived)
.GetFields(BindingFlags.Static | BindingFlags.GetField | BindingFlags.Public)
.Where(t => t.FieldType == typeof(TDerived))
.Select(fieldInfo => new EnumInstanceReflectionInfo(fieldInfo))
.ToList();
private static readonly SortedList<TValue, TDerived> Values =
new SortedList<TValue, TDerived>();
public readonly TValue Value;
private readonly Lazy<string> _name;
protected RichEnum(TValue value)
{
Value = value;
// SortedList doesn't allow duplicates so we don't need to do
// duplicate checking ourselves
Values.Add(value, (TDerived)this);
_name = new Lazy<string>(
() => EnumInstanceToNameMapping
.First(x => ReferenceEquals(this, x.Instance))
.Name);
}
public string Name
{
get { return _name.Value; }
}
public static implicit operator TValue(RichEnum<TValue, TDerived> richEnum)
{
return richEnum.Value;
}
public static TDerived Convert(TValue value)
{
return Values[value];
}
protected override bool Equals(TDerived other)
{
return Value.Equals(other.Value);
}
protected override int ComputeHashCode()
{
return Value.GetHashCode();
}
private class EnumInstanceReflectionInfo
{
private readonly FieldInfo _field;
private readonly Lazy<TDerived> _instance;
public EnumInstanceReflectionInfo(FieldInfo field)
{
_field = field;
_instance = new Lazy<TDerived>(() => (TDerived)field.GetValue(null));
}
public TDerived Instance
{
get { return _instance.Value; }
}
public string Name { get { return _field.Name; } }
}
}
就我而言,这是基于EquatableBase<T>
:
public abstract class EquatableBase<T>
where T : class
{
public override bool Equals(object obj)
{
if (this == obj)
{
return true;
}
T other = obj as T;
if (other == null)
{
return false;
}
return Equals(other);
}
protected abstract bool Equals(T other);
public override int GetHashCode()
{
unchecked
{
return ComputeHashCode();
}
}
protected abstract int ComputeHashCode();
}
上面的代码未包含Mark的所有功能原始答案的!
我发现从这里采取的更简单的解决方案/codereview/7566/enum-vs-int-wrapper-struct我从该链接粘贴了以下代码,以防万一将来无法使用。
struct Day
{
readonly int day;
public static readonly Day Monday = 0;
public static readonly Day Tuesday = 1;
public static readonly Day Wednesday = 2;
public static readonly Day Thursday = 3;
public static readonly Day Friday = 4;
public static readonly Day Saturday = 5;
public static readonly Day Sunday = 6;
private Day(int day)
{
this.day = day;
}
public static implicit operator int(Day value)
{
return value.day;
}
public static implicit operator Day(int value)
{
return new Day(value);
}
}
我创建了此实用程序,以帮助我将Enum转换为PrimitiveEnum并将PrimitiveEnum转换为byte, sbyte, short, ushort, int, uint, long, or ulong
。
因此,从技术上讲,这会将任何枚举转换为其原始值。
public enum MyEnum
{
one = 1, two = 2
}
PrimitiveEnum number = MyEnum.one;
long i = number;
请参阅https://github.com/McKabue/McKabue.Extentions.Utility/blob/master/src/McKabue.Extentions.Utility/Enums/PrimitiveEnum.cs上的提交
using System;
namespace McKabue.Extentions.Utility.Enums
{
/// <summary>
/// <see href="https://stackoverflow.com/q/261663/3563013">
/// Can we define implicit conversions of enums in c#?
/// </see>
/// </summary>
public struct PrimitiveEnum
{
private Enum _enum;
public PrimitiveEnum(Enum _enum)
{
this._enum = _enum;
}
public Enum Enum => _enum;
public static implicit operator PrimitiveEnum(Enum _enum)
{
return new PrimitiveEnum(_enum);
}
public static implicit operator Enum(PrimitiveEnum primitiveEnum)
{
return primitiveEnum.Enum;
}
public static implicit operator byte(PrimitiveEnum primitiveEnum)
{
return Convert.ToByte(primitiveEnum.Enum);
}
public static implicit operator sbyte(PrimitiveEnum primitiveEnum)
{
return Convert.ToSByte(primitiveEnum.Enum);
}
public static implicit operator short(PrimitiveEnum primitiveEnum)
{
return Convert.ToInt16(primitiveEnum.Enum);
}
public static implicit operator ushort(PrimitiveEnum primitiveEnum)
{
return Convert.ToUInt16(primitiveEnum.Enum);
}
public static implicit operator int(PrimitiveEnum primitiveEnum)
{
return Convert.ToInt32(primitiveEnum.Enum);
}
public static implicit operator uint(PrimitiveEnum primitiveEnum)
{
return Convert.ToUInt32(primitiveEnum.Enum);
}
public static implicit operator long(PrimitiveEnum primitiveEnum)
{
return Convert.ToInt64(primitiveEnum.Enum);
}
public static implicit operator ulong(PrimitiveEnum primitiveEnum)
{
return Convert.ToUInt64(primitiveEnum.Enum);
}
}
}
uint
s 标识的东西,而游戏本身通常enum
为此做s,但该框架一无所知。在(uint)
调用框架时必须付出一定的努力。您的想法倒向完美。而不是struct
存储Enum
,我有一个struct IdNumber
,其中存储了,uint
但从Enum
游戏使用的隐式转换了。uint
我可以键入它们IdNumber
,而不用将框架的参数键入为,并且框架可以在内部有效地传递它们,甚至可以对它们进行整体操作。
为枚举类型引入隐式转换会破坏类型安全性,因此不建议这样做。你为什么想这么做?我所看到的唯一用例是,当您要将枚举值放入具有预定义布局的结构中时。但是即使这样,您也可以在结构中使用枚举类型,并告诉Marshaller应该如何处理。
enum YesNo {Yes, No}
可以隐式转换为bool 的枚举。