C# 当位掩码（标志）枚举变得太大时该怎么办
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原文地址: http://stackoverflow.com/questions/1060760/
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What to do when bit mask (flags) enum gets too large
提问by Matthew Vines
I have a very large set of permissions in my application that I represent with a Flags enumeration. It is quickly approaching the practical upper bound of the long data type. And I am forced to come up with a strategy to transition to a different structure soon. Now, I could break this list down into smaller pieces, however, this is already just a subset of the overall permissions for our application, based on our applications layout. We use this distinction extensively for display purposes when managing permissions and I would rather not have to revisit that code at this time if I can avoid it.
我的应用程序中有一组非常大的权限，我用 Flags 枚举表示。它正在迅速接近 long 数据类型的实际上限。我被迫想出一个策略来尽快过渡到不同的结构。现在，我可以将这个列表分解成更小的部分，但是，根据我们的应用程序布局，这已经只是我们应用程序整体权限的一个子集。我们在管理权限时广泛使用这种区别来显示目的，如果我可以避免它，我宁愿此时不必重新访问该代码。
Has anybody else run into this issue? How did you get past it? General examples are fine, but I am most interested in a c# specific example if there are any language specific tricks that I can employ to get the job done.
有没有其他人遇到过这个问题？你是怎么熬过去的？一般示例很好，但我对 ac# 特定示例最感兴趣，如果有任何语言特定的技巧可以用来完成工作。
May not be neccessary, but here is the list of Permissions currently defined for the portion of the app I am dealing with.
可能不是必需的，但这里是当前为我正在处理的应用程序部分定义的权限列表。
//Subgroup WebAgent
[Flags]
public enum WebAgentPermission : long
{
[DescriptionAttribute("View Rule Group")]
ViewRuleGroup = 1,
[DescriptionAttribute("Add Rule Group")]
AddRuleGroup = 2,
[DescriptionAttribute("Edit Rule Group")]
EditRuleGroup = 4,
[DescriptionAttribute("Delete Rule Group")]
DeleteRuleGroup = 8,
[DescriptionAttribute("View Rule")]
ViewRule = 16,
[DescriptionAttribute("Add Rule")]
AddRule = 32,
[DescriptionAttribute("Edit Rule")]
EditRule = 64,
[DescriptionAttribute("Delete Rule")]
DeleteRule = 128,
[DescriptionAttribute("View Location")]
ViewLocation = 256,
[DescriptionAttribute("Add Location")]
AddLocation = 512,
[DescriptionAttribute("Edit Location")]
EditLocation = 1024,
[DescriptionAttribute("Delete Location")]
DeleteLocation = 2048,
[DescriptionAttribute("View Volume Statistics")]
ViewVolumeStatistics = 4096,
[DescriptionAttribute("Edit Volume Statistics")]
EditVolumeStatistics = 8192,
[DescriptionAttribute("Upload Volume Statistics")]
UploadVolumeStatistics = 16384,
[DescriptionAttribute("View Role")]
ViewRole = 32768,
[DescriptionAttribute("Add Role")]
AddRole = 65536,
[DescriptionAttribute("Edit Role")]
EditRole = 131072,
[DescriptionAttribute("Delete Role")]
DeleteRole = 262144,
[DescriptionAttribute("View User")]
ViewUser = 524288,
[DescriptionAttribute("Add User")]
AddUser = 1048576,
[DescriptionAttribute("Edit User")]
EditUser = 2097152,
[DescriptionAttribute("Delete User")]
DeleteUser = 4194304,
[DescriptionAttribute("Assign Permissions To User")]
AssignPermissionsToUser = 8388608,
[DescriptionAttribute("Change User Password")]
ChangeUserPassword = 16777216,
[DescriptionAttribute("View Audit Logs")]
ViewAuditLogs = 33554432,
[DescriptionAttribute("View Team")]
ViewTeam = 67108864,
[DescriptionAttribute("Add Team")]
AddTeam = 134217728,
[DescriptionAttribute("Edit Team")]
EditTeam = 268435456,
[DescriptionAttribute("Delete Team")]
DeleteTeam = 536870912,
[DescriptionAttribute("View Web Agent Reports")]
ViewWebAgentReports = 1073741824,
[DescriptionAttribute("View All Locations")]
ViewAllLocations = 2147483648,
[DescriptionAttribute("Access to My Search")]
AccessToMySearch = 4294967296,
[DescriptionAttribute("Access to Pespective Search")]
AccessToPespectiveSearch = 8589934592,
[DescriptionAttribute("Add Pespective Search")]
AddPespectiveSearch = 17179869184,
[DescriptionAttribute("Edit Pespective Search")]
EditPespectiveSearch = 34359738368,
[DescriptionAttribute("Delete Pespective Search")]
DeletePespectiveSearch = 68719476736,
[DescriptionAttribute("Access to Search")]
AccessToSearch = 137438953472,
[DescriptionAttribute("View Form Roles")]
ViewFormRole = 274877906944,
[DescriptionAttribute("Add / Edit Form Roles")]
AddFormRole = 549755813888,
[DescriptionAttribute("Delete UserFormRolesDifferenceMasks")]
DeleteFormRole = 1099511627776,
[DescriptionAttribute("Export Locations")]
ExportLocations = 2199023255552,
[DescriptionAttribute("Import Locations")]
ImportLocations = 4398046511104,
[DescriptionAttribute("Manage Location Levels")]
ManageLocationLevels = 8796093022208,
[DescriptionAttribute("View Job Title")]
ViewJobTitle = 17592186044416,
[DescriptionAttribute("Add Job Title")]
AddJobTitle = 35184372088832,
[DescriptionAttribute("Edit Job Title")]
EditJobTitle = 70368744177664,
[DescriptionAttribute("Delete Job Title")]
DeleteJobTitle = 140737488355328,
[DescriptionAttribute("View Dictionary Manager")]
ViewDictionaryManager = 281474976710656,
[DescriptionAttribute("Add Dictionary Manager")]
AddDictionaryManager = 562949953421312,
[DescriptionAttribute("Edit Dictionary Manager")]
EditDictionaryManager = 1125899906842624,
[DescriptionAttribute("Delete Dictionary Manager")]
DeleteDictionaryManager = 2251799813685248,
[DescriptionAttribute("View Choice Manager")]
ViewChoiceManager = 4503599627370496,
[DescriptionAttribute("Add Choice Manager")]
AddChoiceManager = 9007199254740992,
[DescriptionAttribute("Edit Chioce Manager")]
EditChoiceManager = 18014398509481984,
[DescriptionAttribute("Delete Choice Manager")]
DeleteChoiceManager = 36028797018963968,
[DescriptionAttribute("Import Export Choices")] //57
ImportExportChoices = 72057594037927936
}
采纳答案by Fredrik M?rk
I see values from at least a handful of different enumerations in there...
我从那里至少看到了一些不同枚举的值......
My first thought was to approach the problem by splitting the permissions up in logical groups (RuleGroupPermissions, RulePermissions, LocationPermissions, ...), and then having a class (WebAgentPermissions) exposing a property for each permission enum type.
我的第一个想法是通过将权限分成逻辑组 ( RuleGroupPermissions, RulePermissions, LocationPermissions, ...)来解决这个问题，然后让一个类 ( WebAgentPermissions) 为每个权限枚举类型公开一个属性。
Since the permission values seem repetitive, you could probably get away with a single enum in the end:
由于权限值似乎是重复的，因此您最终可能会使用单个枚举：
[Flags]
public enum Permissions
{
View = 1,
Add = 2,
Edit = 4,
Delete = 8
}
And then have the WebAgentPermissionsclass expose a property for each area where permissions are to be set;
然后让WebAgentPermissions该类为每个要设置权限的区域公开一个属性；
class WebAgentPermissions
{
public Permissions RuleGroup { get; set; }
public Permissions Rule { get; set; }
public Permissions Location { get; set; }
// and so on...
}
回答by the.jxc
Language documentation says:
语言文档说：
http://msdn.microsoft.com/en-us/library/system.flagsattribute.aspx
http://msdn.microsoft.com/en-us/library/system.flagsattribute.aspx
"The underlying type is Int32 and so the maximum single bit flag is 1073741824 and obviously there are a total of 32 flags for each enum."
“底层类型是 Int32，因此最大的单个位标志是 1073741824，显然每个枚举共有 32 个标志。”
However... UPDATED:
但是......更新：
Commenter is correct. Check out this:
评论者是正确的。看看这个：
http://msdn.microsoft.com/en-us/library/ms182147(VS.80).aspx
http://msdn.microsoft.com/en-us/library/ms182147(VS.80).aspx
Int32 is only the DEFAULT datatype! In fact you can specify Int64.
Int32 只是 DEFAULT 数据类型！事实上，您可以指定 Int64。
public enum MyEnumType : Int64
...allowing up to 64 values. But that certainly seems to be the maximum, after that you're going to be looking at re-engineering. Without knowing too much about the rest of your solution, I can't say exactly what might suit. But an array (or hash-map) of privilege identifiers is probably the most natural approach.
...最多允许 64 个值。但这当然似乎是最大的，之后您将考虑重新设计。在对您的解决方案的其余部分知之甚少的情况下，我无法确切说出可能适合的内容。但是特权标识符的数组（或哈希映射）可能是最自然的方法。
回答by mqp
In C#, one flexible way to represent a value that is sort of an enumeration but more flexible is to represent it as a static class with precooked values available, like this:
在 C# 中，一种表示类似于枚举但更灵活的值的灵活方法是将其表示为具有可用预煮值的静态类，如下所示：
public sealed class WebAgentPermission
{
private long ID;
public static readonly WebAgentPermission
ViewRuleGroup = new WebAgentPermission { ID = 1 };
public static readonly WebAgentPermission
AddRuleGroup = new WebAgentPermission { ID = 2 };
private WebAgentPermission() { }
// considerations: override equals/gethashcode, probably override tostring,
// maybe implicit cast to/from long, maybe other stuff
}
Alternatively, just split the thing up; it looks like you could, if you really tried.
或者，把事情分开；看起来你可以，如果你真的尝试过。
回答by shahkalpesh
I have not been in this situation.
我没有遇到过这种情况。
Here is what I think, create separate enums for each of the category & accept those as parameters.
这是我的想法，为每个类别创建单独的枚举并接受它们作为参数。
RuleGroupPermission
None = 0
ViewRuleGroup = 1,
AddRuleGroup = 2,
EditRuleGroup = 4,
DeleteRuleGroup = 8,
LocationOperations
None = 0
Add = 1
View = 2
Delete = 4
void setPermission(RuleGroupPermission ruleGroupOpsAllowed, LocationOperations locationOptions)
{
...
}
EDIT: Look at how messagebox.show does it. OK, OKCancel separated from Question, Information, Exclamation.
编辑：看看 messagebox.show 是如何做到的。OK、OKCancel 与 Question、Information、Exclamation 分开。
回答by Talljoe
If I were in control of this application, I would probably come up with a common set of permissions (View, Add, Edit, Delete, Upload/Import) and a set of resources (Users, Roles, Rules, etc). On the web page find the resource type associated with that page and then check the permissions. Perhaps something like:
如果我控制了这个应用程序，我可能会想出一组通用的权限（查看、添加、编辑、删除、上传/导入）和一组资源（用户、角色、规则等）。在网页上找到与该页面关联的资源类型，然后检查权限。也许是这样的：
Permissions perms = agent.GetPermissions(ResourceType.User);
if((perms & Permissions.View) == Permissions.View) { /* do work */ }
or
或者
Permissions perms = agent.Permissions[ResourceType.User];
if((perms & Permissions.View) == Permissions.View) { /* do work */ }
or even
甚至
if(agent.IsAuthorized(ResourceType.User, Permissions.View)) { /* do work */ }
You have a couple of permissions that don't make sense with everything else (Assign Permissoins to user, to name one). I'm not sure how I would handle that based on how little I know the problem.
您有一些对其他所有内容都没有意义的权限（将权限分配给用户，仅举一个例子）。根据我对这个问题知之甚少，我不确定我将如何处理。
回答by Bruce Pierson
This turned out to be a more common problem than I thought it would be, where I was representing CSS classes as flags types and there were more than 64 possibilities. I've taken all I learned from that process and turned it into a reusable pattern, albeit since it's a struct, it's a copy-and-paste type pattern.
结果证明这是一个比我想象的更常见的问题，我将 CSS 类表示为标志类型，并且有超过 64 种可能性。我把我从那个过程中学到的所有东西都变成了一个可重用的模式，尽管因为它是一个结构，它是一个复制粘贴类型的模式。
This is the BigFlags"enumerated type". It uses either BigIntegerfrom System.Numerics, or if there is no way you can reference that assembly, there is a fallback that uses BitArrayby simply turning off the NUMERICSpreprocessor directive.
这就是BigFlags“枚举类型”。它使用BigIntegerfrom System.Numerics，或者如果您无法引用该程序集，则可以BitArray通过简单地关闭NUMERICS预处理器指令来使用回退。
It behaves remarkably like a Flagsenum, even defining such things as HasFlag(...), GetNames(), GetValues(), TryParse(...), a TypeConverter, IConvertible, etc. Since it does define a TypeConverterand IConvertible, it's also suitable for storing in a data store, albeit always as a string or text data type.
它的行为非常像Flags枚举，甚至定义了诸如HasFlag(...), GetNames(), GetValues(), TryParse(...), a TypeConverter,IConvertible等。由于它确实定义了TypeConverterand IConvertible，因此它也适合存储在数据存储中，尽管总是作为字符串或文本数据类型。
You expose the "enum" values as public static readonlymembers. Combined enum values are exposed as get-only properties.
您将“枚举”值公开为public static readonly成员。组合的枚举值作为 get-only 属性公开。
To use it, copy and paste the code, then do a search and replace on BigFlagswith your struct name, then delete the enums in the TODOsection and add your values.
要使用它，请复制并粘贴代码，然后进行搜索并替换BigFlags为您的结构名称，然后删除该TODO部分中的枚举并添加您的值。
Hope somebody finds it useful.
希望有人觉得它有用。
#define NUMERICS
using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
#if NUMERICS
using System.Numerics;
#endif
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
namespace Aim
{
/// <summary>
/// The BigFlags struct behaves like a Flags enumerated type.
/// <para>
/// Note that if this struct will be stored in some type of data
/// store, it should be stored as a string type. There are two
/// reasons for this:
/// </para>
/// <para>
/// 1. Presumably, this pattern is being used because the number
/// of values will exceed 64 (max positions in a long flags enum).
/// Since this is so, there is in any case no numeric type which
/// can store all the possible combinations of flags.
/// </para>
/// <para>
/// 2. The "enum" values are assigned based on the order that the
/// static public fields are defined. It is much safer to store
/// these fields by name in case the fields are rearranged. This
/// is particularly important if this represents a permission set!
/// </para>
/// </summary>
[
TypeConverter( typeof( BigFlagsConverter ) )
]
public struct BigFlags : IEquatable<BigFlags>,
IComparable<BigFlags>, IComparable, IConvertible
{
#region State...
private static readonly List<FieldInfo> Fields;
private static readonly List<BigFlags> FieldValues;
#if NUMERICS
private static readonly bool ZeroInit = true;
private BigInteger Value;
/// <summary>
/// Creates a value taking ZeroInit into consideration.
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
private static BigInteger CreateValue( int index )
{
if( ZeroInit && index == 0 )
{
return 0;
}
int idx = ZeroInit ? index - 1 : index;
return new BigInteger( 1 ) << idx;
}
#else
private BitArray Array;
/// <summary>
/// Lazy-initialized BitArray.
/// </summary>
private BitArray Bits
{
get
{
if( null == Array )
{
Array = new BitArray( Fields.Count );
}
return Array;
}
}
#endif
#endregion ...State
#region Construction...
/// <summary>
/// Static constructor. Sets the static public fields.
/// </summary>
static BigFlags()
{
Fields = typeof( BigFlags ).GetFields(
BindingFlags.Public | BindingFlags.Static ).ToList();
FieldValues = new List<BigFlags>();
for( int i = 0; i < Fields.Count; i++ )
{
var field = Fields[i];
var fieldVal = new BigFlags();
#if NUMERICS
fieldVal.Value = CreateValue( i );
#else
fieldVal.Bits.Set( i, true );
#endif
field.SetValue( null, fieldVal );
FieldValues.Add( fieldVal );
}
}
#endregion ...Construction
#region Operators...
/// <summary>
/// OR operator. Or together BigFlags instances.
/// </summary>
/// <param name="lhs"></param>
/// <param name="rhs"></param>
/// <returns></returns>
public static BigFlags operator |( BigFlags lhs, BigFlags rhs )
{
var result = new BigFlags();
#if NUMERICS
result.Value = lhs.Value | rhs.Value;
#else
// BitArray is modified in place - always copy!
result.Array = new BitArray( lhs.Bits ).Or( rhs.Bits );
#endif
return result;
}
/// <summary>
/// AND operator. And together BigFlags instances.
/// </summary>
/// <param name="lhs"></param>
/// <param name="rhs"></param>
/// <returns></returns>
public static BigFlags operator &( BigFlags lhs, BigFlags rhs )
{
var result = new BigFlags();
#if NUMERICS
result.Value = lhs.Value & rhs.Value;
#else
// BitArray is modified in place - always copy!
result.Array = new BitArray( lhs.Bits ).And( rhs.Bits );
#endif
return result;
}
/// <summary>
/// XOR operator. Xor together BigFlags instances.
/// </summary>
/// <param name="lhs"></param>
/// <param name="rhs"></param>
/// <returns></returns>
public static BigFlags operator ^( BigFlags lhs, BigFlags rhs )
{
var result = new BigFlags();
#if NUMERICS
result.Value = lhs.Value ^ rhs.Value;
#else
// BitArray is modified in place - always copy!
result.Array = new BitArray( lhs.Bits ).Xor( rhs.Bits );
#endif
return result;
}
/// <summary>
/// Equality operator.
/// </summary>
/// <param name="lhs"></param>
/// <param name="rhs"></param>
/// <returns></returns>
public static bool operator ==( BigFlags lhs, BigFlags rhs )
{
return lhs.Equals( rhs );
}
/// <summary>
/// Inequality operator.
/// </summary>
/// <param name="lhs"></param>
/// <param name="rhs"></param>
/// <returns></returns>
public static bool operator !=( BigFlags lhs, BigFlags rhs )
{
return !( lhs == rhs );
}
#endregion ...Operators
#region System.Object Overrides...
/// <summary>
/// Overridden. Returns a comma-separated string.
/// </summary>
/// <returns></returns>
public override string ToString()
{
#if NUMERICS
if( ZeroInit && Value == 0 )
{
return Fields[0].Name;
}
#endif
var names = new List<string>();
for( int i = 0; i < Fields.Count; i++ )
{
#if NUMERICS
if( ZeroInit && i == 0 )
continue;
var bi = CreateValue( i );
if( ( Value & bi ) == bi )
names.Add( Fields[i].Name );
#else
if( Bits[i] )
names.Add( Fields[i].Name );
#endif
}
return String.Join( ", ", names );
}
/// <summary>
/// Overridden. Compares equality with another object.
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public override bool Equals( object obj )
{
if( obj is BigFlags )
{
return Equals( (BigFlags)obj );
}
return false;
}
/// <summary>
/// Overridden. Gets the hash code of the internal BitArray.
/// </summary>
/// <returns></returns>
public override int GetHashCode()
{
#if NUMERICS
return Value.GetHashCode();
#else
int hash = 17;
for( int i = 0; i < Bits.Length; i++ )
{
if( Bits[i] )
hash ^= i;
}
return hash;
#endif
}
#endregion ...System.Object Overrides
#region IEquatable<BigFlags> Members...
/// <summary>
/// Strongly-typed equality method.
/// </summary>
/// <param name="other"></param>
/// <returns></returns>
public bool Equals( BigFlags other )
{
#if NUMERICS
return Value == other.Value;
#else
for( int i = 0; i < Bits.Length; i++ )
{
if( Bits[i] != other.Bits[i] )
return false;
}
return true;
#endif
}
#endregion ...IEquatable<BigFlags> Members
#region IComparable<BigFlags> Members...
/// <summary>
/// Compares based on highest bit set. Instance with higher
/// bit set is bigger.
/// </summary>
/// <param name="other"></param>
/// <returns></returns>
public int CompareTo( BigFlags other )
{
#if NUMERICS
return Value.CompareTo( other.Value );
#else
for( int i = Bits.Length - 1; i >= 0; i-- )
{
bool thisVal = Bits[i];
bool otherVal = other.Bits[i];
if( thisVal && !otherVal )
return 1;
else if( !thisVal && otherVal )
return -1;
}
return 0;
#endif
}
#endregion ...IComparable<BigFlags> Members
#region IComparable Members...
int IComparable.CompareTo( object obj )
{
if( obj is BigFlags )
{
return CompareTo( (BigFlags)obj );
}
return -1;
}
#endregion ...IComparable Members
#region IConvertible Members...
/// <summary>
/// Returns TypeCode.Object.
/// </summary>
/// <returns></returns>
public TypeCode GetTypeCode()
{
return TypeCode.Object;
}
bool IConvertible.ToBoolean( IFormatProvider provider )
{
throw new NotSupportedException();
}
byte IConvertible.ToByte( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToByte( Value );
#else
throw new NotSupportedException();
#endif
}
char IConvertible.ToChar( IFormatProvider provider )
{
throw new NotSupportedException();
}
DateTime IConvertible.ToDateTime( IFormatProvider provider )
{
throw new NotSupportedException();
}
decimal IConvertible.ToDecimal( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToDecimal( Value );
#else
throw new NotSupportedException();
#endif
}
double IConvertible.ToDouble( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToDouble( Value );
#else
throw new NotSupportedException();
#endif
}
short IConvertible.ToInt16( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToInt16( Value );
#else
throw new NotSupportedException();
#endif
}
int IConvertible.ToInt32( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToInt32( Value );
#else
throw new NotSupportedException();
#endif
}
long IConvertible.ToInt64( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToInt64( Value );
#else
throw new NotSupportedException();
#endif
}
sbyte IConvertible.ToSByte( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToSByte( Value );
#else
throw new NotSupportedException();
#endif
}
float IConvertible.ToSingle( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToSingle( Value );
#else
throw new NotSupportedException();
#endif
}
string IConvertible.ToString( IFormatProvider provider )
{
return ToString();
}
object IConvertible.ToType( Type conversionType, IFormatProvider provider )
{
var tc = TypeDescriptor.GetConverter( this );
return tc.ConvertTo( this, conversionType );
}
ushort IConvertible.ToUInt16( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToUInt16( Value );
#else
throw new NotSupportedException();
#endif
}
uint IConvertible.ToUInt32( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToUInt32( Value );
#else
throw new NotSupportedException();
#endif
}
ulong IConvertible.ToUInt64( IFormatProvider provider )
{
#if NUMERICS
return Convert.ToUInt64( Value );
#else
throw new NotSupportedException();
#endif
}
#endregion ...IConvertible Members
#region Public Interface...
/// <summary>
/// Checks <paramref name="flags"/> to see if all the bits set in
/// that flags are also set in this flags.
/// </summary>
/// <param name="flags"></param>
/// <returns></returns>
public bool HasFlag( BigFlags flags )
{
return ( this & flags ) == flags;
}
/// <summary>
/// Gets the names of this BigFlags enumerated type.
/// </summary>
/// <returns></returns>
public static string[] GetNames()
{
return Fields.Select( x => x.Name ).ToArray();
}
/// <summary>
/// Gets all the values of this BigFlags enumerated type.
/// </summary>
/// <returns></returns>
public static BigFlags[] GetValues()
{
return FieldValues.ToArray();
}
/// <summary>
/// Standard TryParse pattern. Parses a BigFlags result from a string.
/// </summary>
/// <param name="s"></param>
/// <param name="result"></param>
/// <returns></returns>
public static bool TryParse( string s, out BigFlags result )
{
result = new BigFlags();
if( String.IsNullOrEmpty( s ) )
return true;
var fieldNames = s.Split( ',' );
foreach( var f in fieldNames )
{
var field = Fields.FirstOrDefault( x =>
String.Equals( x.Name, f.Trim(),
StringComparison.OrdinalIgnoreCase ) );
if( null == field )
{
result = new BigFlags();
return false;
}
#if NUMERICS
int i = Fields.IndexOf( field );
result.Value |= CreateValue( i );
#else
result.Bits.Set( Fields.IndexOf( field ), true );
#endif
}
return true;
}
//
// Expose "enums" as public static readonly fields.
// TODO: Replace this section with your "enum" values.
//
public static readonly BigFlags None;
public static readonly BigFlags FirstValue;
public static readonly BigFlags ValueTwo;
public static readonly BigFlags ValueThree;
public static readonly BigFlags ValueFour;
public static readonly BigFlags ValueFive;
public static readonly BigFlags ValueSix;
public static readonly BigFlags LastValue;
/// <summary>
/// Expose flagged combinations as get-only properties.
/// </summary>
public static BigFlags FirstLast
{
get
{
return BigFlags.FirstValue | BigFlags.LastValue;
}
}
#endregion ...Public Interface
}
/// <summary>
/// Converts objects to and from BigFlags instances.
/// </summary>
public class BigFlagsConverter : TypeConverter
{
/// <summary>
/// Can convert to string only.
/// </summary>
/// <param name="context"></param>
/// <param name="destinationType"></param>
/// <returns></returns>
public override bool CanConvertTo( ITypeDescriptorContext context,
Type destinationType )
{
return destinationType == typeof( String );
}
/// <summary>
/// Can convert from any object.
/// </summary>
/// <param name="context"></param>
/// <param name="sourceType"></param>
/// <returns></returns>
public override bool CanConvertFrom( ITypeDescriptorContext context,
Type sourceType )
{
return true;
}
/// <summary>
/// Converts BigFlags to a string.
/// </summary>
/// <param name="context"></param>
/// <param name="culture"></param>
/// <param name="value"></param>
/// <param name="destinationType"></param>
/// <returns></returns>
public override object ConvertTo( ITypeDescriptorContext context,
CultureInfo culture, object value, Type destinationType )
{
if( value is BigFlags && CanConvertTo( destinationType ) )
return value.ToString();
return null;
}
/// <summary>
/// Attempts to parse <paramref name="value"/> and create and
/// return a new BigFlags instance.
/// </summary>
/// <param name="context"></param>
/// <param name="culture"></param>
/// <param name="value"></param>
/// <returns></returns>
public override object ConvertFrom( ITypeDescriptorContext context,
CultureInfo culture, object value )
{
var s = Convert.ToString( value );
BigFlags result;
BigFlags.TryParse( s, out result );
return result;
}
}
}
回答by DavidMoksha
Not an answer to your question, but a related suggestion: we use bitshifting to specify the numeric values, like so:
不是您问题的答案，而是相关建议：我们使用位移来指定数值，如下所示：
[Flags]
public enum MyEnumFlags : Int64
{
None = 0,
A = 1 << 0,
B = 1 << 1,
C = 1 << 2,
D = 1 << 3,
E = 1 << 4,
F = 1 << 5,
...etc...
Not so important for the first ten, but after that it gets really handy.
前十个不是那么重要，但之后它变得非常方便。
