从C＃.NET 2.0公开动态枚举的内部字段“value__”

Making public the internal field “value__” of dynamic enum from C# .NET 2.0

在Unity中，我创建了一个动态枚举，并成功地将其保存到生成的.dll中，如下所示：msdn文章和此处：C中的动态枚举#我刚刚在动态创建的枚举上添加了flagsattribute

但我注意到内部字段"value_uuuu"在.NET 2.0上是私有的。因此，当我在另一个C应用程序中使用此dll时，我不能直接将枚举值强制转换为int或获取精确的屏蔽值。请注意，在.NET 4.0及更高版本中，"value_uuuu"字段是公共的。还要注意，如果您在c中在2.0 dll中创建一个经典的公共枚举，那么这个"value"也是公共的(在dll中)。

所以我的问题是如何使用EnumBuilder在Mono.NET 2.0中公开这个特殊字段？

这里是生成枚举的代码：

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static bool CreateEnumerators(AppDomain currentDomain, AssemblyName asmName, string enumName, string relativePathName ="")
{
string targetPathName = currentDomain.BaseDirectory + relativePathName;

if (!System.IO.Directory.Exists(targetPathName))
System.IO.Directory.CreateDirectory(targetPathName);

// Create a dynamic assembly in the current application domain,
// and allow it to be executed and saved to disk.
AssemblyBuilder asmBuilder = currentDomain.DefineDynamicAssembly(asmName,
AssemblyBuilderAccess.RunAndSave,
targetPathName);

// Define a dynamic module
// For a single-module assembly, the module has the same name as the assembly.
ModuleBuilder mdlBuilder = asmBuilder.DefineDynamicModule(asmName.Name,
asmName.Name +".dll");

// Define a public enumeration and an underlying type of Integer.
EnumBuilder enumBuilder = mdlBuilder.DefineEnum(asmName.Name +"." + enumName,
TypeAttributes.Public, typeof(int));

// Get data from database
int key = 1;
foreach (string literalName in enumLiteralNames)
{
enumBuilder.DefineLiteral(literalName, key);
key = key << 1;
}

// set FlagsAttribute
ConstructorInfo cinfo = typeof(FlagsAttribute).GetConstructor(Type.EmptyTypes);
CustomAttributeBuilder flagsAttribute = new CustomAttributeBuilder(cinfo, new object[] { });
enumBuilder.SetCustomAttribute(flagsAttribute);

// Create the enum
Type finished = enumBuilder.CreateType();

// Check if"value__" is private (by default it is from .NET 2.0 to 3.5)
Console.WriteLine("
Check special field:
");
{
FieldInfo fi = finished.GetField("value__", BindingFlags.Instance | BindingFlags.NonPublic);
if (fi != null)
Console.WriteLine("found as private:" + finished.Name +"." + fi.Name +"{" + fi.Attributes +"}");
}

// in .NET 4.0 and above"value__" is part of the public fields
Console.WriteLine("Fields:");
foreach (FieldInfo fi in finished.GetFields())
{

Console.WriteLine(finished.Name +"." + fi.Name +"" + fi.GetType() +"");

}

// Finally, save the assembly
string assemblyName = asmName.Name +".dll";
asmBuilder.Save(assemblyName);
Console.WriteLine("
Created assembly '" + targetPathName + assemblyName +"'");

return true;
}

这里只是一个产生错误的简单用法：

1 2	MyTypes.MEnum eTypePhysical = MyTypes.MEnum.Physical; Debug.Log("Value =" + (int)eTypePhysical);

错误：

1 2	Internal compiler error. See the console log for more information. output was:error CS0656: The compiler required member `MyTypes.MyEnum.value__' could not be found or is inaccessible error CS0656: The compiler required member `MyTypes.MyEnum.value__' could not be found or is inaccessible

对枚举内部值的任何访问都会产生相同的错误。

我无法在使用Microsft.net 2.0框架生成并使用dll的Visual Studio上获得任何错误。但通过检查dll，我仍然看到动态枚举的"value_uuuuu"是私有的，这显然是导致统一错误的原因。这就是为什么我想知道是否可以使用.NET 2.0的EnumBuilder接口将其声明为公共的原因。

相关讨论

我用System.Reflection on.NET 2.0尝试了很多不同的方法来解决这个问题，但都没有成功。IE：我尝试向程序集添加InternalVisibleToFlags，使用类型生成器从头创建枚举类型。但是它们都不起作用，因为在最近的情况下，显然有一些约束阻止从System.Enum使用继承，当您使用NET Framework 2.0动态构建类型时。我终于切换到为.NET 2.0目标编译的C lib mono.cecil。下面是使用mono.cecil使用公共特殊字段"value_uuu"构建枚举的代码。

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static void CreateEnumAssembly(string asmName, string relativePathName ="")
{
// get asm version from database
Version asmVersion = new Version(0,0,0,0);
AssemblyNameDefinition asmNameDef = new AssemblyNameDefinition(asmName, asmVersion);
AssemblyDefinition asmDef = AssemblyDefinition.CreateAssembly (asmNameDef, asmName, ModuleKind.Dll);

// get enum name from database
string enumName ="myEnum";

// define a new enum type
TypeDefinition enumTypeDef;
asmDef.MainModule.Types.Add (enumTypeDef = new TypeDefinition ( asmName, enumName, TypeAttributes.Public | TypeAttributes.Sealed, asmDef.MainModule.Import(typeof(System.Enum) )));
// - add FlagsAttribute to the enum
CustomAttribute flagsAttribute = new CustomAttribute ( asmDef.MainModule.Import(typeof(FlagsAttribute).GetConstructor(Type.EmptyTypes)) );
enumTypeDef.CustomAttributes.Add( flagsAttribute );

// define the special field"value__" of the enum
enumTypeDef.Fields.Add (new FieldDefinition ("value__", FieldAttributes.Public | FieldAttributes.SpecialName | FieldAttributes.RTSpecialName, asmDef.MainModule.Import (typeof(System.Int32))));

int shift = 0;
// get literals and their values from database and define them in the enum
foreach (var literalName in literalNames)
{
FieldDefinition literalDef;
enumTypeDef.Fields.Add (literalDef = new FieldDefinition (literalName, FieldAttributes.Public | FieldAttributes.Static | FieldAttributes.Literal | FieldAttributes.HasDefault, enumTypeDef));
System.Int32 key = 1 << shift++;
literalDef.Constant = key;
}

string filename = relativePathName+asmNameDef.Name+".dll";
asmDef.Write(filename);
Debug.Log ("Created assembly '"+filename+"'");
}