c#如何设置StructLayoutAttribute.通过反射打包

我正在通过反射动态地创建一个c#结构体，当我在调试器中检查结构体的类型时，我注意到StructLayoutAttribute。Pack默认为8。我想将Pack设置为1。

本质上，我想通过反射来完成可以通过将这个属性添加到结构体声明中来完成的事情:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]

我试过在创建类型后使用反射，但由于StructLayoutAttribute属性没有Setter，它会抛出异常。

我的预感是，它需要发生在调用ModuleBuilder。DefineType(我目前正在设置LayoutKind等)，但我没有看到任何明显对应的TypeAttribute。

感谢任何提示。该类的完整代码在这里:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.Reflection.Emit;
namespace AcmeCo.Serializable
{
    public class DynamicSimStructBuilder
    {
        private static Type structType;
        public static object GetStructInstance() {
            object ptInstance = Activator.CreateInstance(GetStruct(), new object[] { });
            return ptInstance;
        }
        public static Type GetStruct() {
            if (structType != null) {
               return structType; 
            }
            AppDomain myDomain = AppDomain.CurrentDomain;
            AssemblyName myAsmName = new AssemblyName("MyDynamicAssembly");
            AssemblyBuilder myAsmBuilder =
               myDomain.DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess.RunAndSave);
            ModuleBuilder structModule = myAsmBuilder.DefineDynamicModule("StructModule", "MyDynamicAssembly.dll");
            TypeBuilder structTypeBld = structModule.DefineType("AcmeCo.ThirdPartyAPIWrapper.DyanmicStruct", TypeAttributes.Public |
                TypeAttributes.Sealed | TypeAttributes.SequentialLayout | 
                TypeAttributes.Serializable | TypeAttributes.AnsiClass, typeof(ValueType));
            // use a set of variables defined in an XML file to create Fields on the struct
            ThirdPartyAPIVariableCollection collection = ThirdPartyAPIVariableCollection.Deserialize();
            foreach (ThirdPartyAPIVariable variable in collection.ThirdPartyAPIVariables)
            {
                FieldBuilder field = structTypeBld.DefineField(variable.Name, Type.GetType(variable.SystemDataType, true) , FieldAttributes.Public);
            }
            // Base class and base class constructor.
            Type objType = Type.GetType("System.Object");
            ConstructorInfo objCtor = objType.GetConstructor(new Type[] { });
            Type[] ctorParams = { };
            ConstructorBuilder pointCtor =
               structTypeBld.DefineConstructor(MethodAttributes.Public,
                                              CallingConventions.Standard, ctorParams);
            ILGenerator ctorIL = pointCtor.GetILGenerator();
            // Build the constructor. Begin by invoking the base class
            // constructor. The zero-index parameter of the constructor
            // is the new instance. Store the values of the fields.
            ctorIL.Emit(OpCodes.Ldarg_0);
            ctorIL.Emit(OpCodes.Call, objCtor);
            ctorIL.Emit(OpCodes.Ret);

            // Create the type, and then create an instance of the type 
            // (or not, doesn't hurt to comment the CreateInstance line out...)
            Type ptType = structTypeBld.CreateType();
            object ptInstance = Activator.CreateInstance(ptType, new object[] { });
            DynamicSimStructBuilder.structType = ptType;
            int sizeOfNewData = System.Runtime.InteropServices.Marshal.SizeOf(ptType);
            Console.WriteLine("New type is: " + sizeOfNewData);
            // save the newly created type to a DLL for use later
            // (or not, doesn't hurt to comment the next line out...)
            myAsmBuilder.Save("MyDynamicAssembly.dll");
            return ptType;
        }
    }
}