FieldBuilder Class

using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
using System.Security.Permissions;

public class FieldBuilder_Sample
{
   private static Type CreateType(AppDomain currentDomain)
   {

      // Create an assembly.
      AssemblyName myAssemblyName = new AssemblyName();
      myAssemblyName.Name = "DynamicAssembly";
      AssemblyBuilder myAssembly =
                     currentDomain.DefineDynamicAssembly(myAssemblyName,AssemblyBuilderAccess.Run);
      // Create a dynamic module in Dynamic Assembly.
      ModuleBuilder myModuleBuilder=myAssembly.DefineDynamicModule("MyModule");
      // Define a public class named "MyClass" in the assembly.
      TypeBuilder myTypeBuilder= myModuleBuilder.DefineType("MyClass",TypeAttributes.Public);

      // Define a private String field named "MyField" in the type.
      FieldBuilder myFieldBuilder= myTypeBuilder.DefineField("MyField",
          typeof(string),FieldAttributes.Private|FieldAttributes.Static);
      // Create the constructor.
      Type[] constructorArgs = { typeof(String) };
      ConstructorBuilder constructor = myTypeBuilder.DefineConstructor(
         MethodAttributes.Public, CallingConventions.Standard, constructorArgs);
      ILGenerator constructorIL = constructor.GetILGenerator();
      constructorIL.Emit(OpCodes.Ldarg_0);
      ConstructorInfo superConstructor = typeof(Object).GetConstructor(new Type[0]);
      constructorIL.Emit(OpCodes.Call, superConstructor);
      constructorIL.Emit(OpCodes.Ldarg_0);
      constructorIL.Emit(OpCodes.Ldarg_1);
      constructorIL.Emit(OpCodes.Stfld, myFieldBuilder);
      constructorIL.Emit(OpCodes.Ret);

      // Create the MyMethod method.
      MethodBuilder myMethodBuilder= myTypeBuilder.DefineMethod("MyMethod",
                           MethodAttributes.Public,typeof(String),null);
      ILGenerator methodIL = myMethodBuilder.GetILGenerator();
      methodIL.Emit(OpCodes.Ldarg_0);
      methodIL.Emit(OpCodes.Ldfld, myFieldBuilder);
      methodIL.Emit(OpCodes.Ret);
      Console.WriteLine("Name               :"+myFieldBuilder.Name);
      Console.WriteLine("DeclaringType      :"+myFieldBuilder.DeclaringType);
      Console.WriteLine("Type               :"+myFieldBuilder.FieldType);
      Console.WriteLine("Token              :"+myFieldBuilder.GetToken().Token);
      return myTypeBuilder.CreateType();
   }

   [PermissionSetAttribute(SecurityAction.Demand, Name="FullTrust")]
   public static void Main()
   {
      try
      {
         Type myType = CreateType(Thread.GetDomain());
         // Create an instance of the "HelloWorld" class.
         Object helloWorld = Activator.CreateInstance(myType, new Object[] { "HelloWorld" });
         // Invoke the "MyMethod" method of the "MyClass" class.
         Object myObject  = myType.InvokeMember("MyMethod",
                        BindingFlags.InvokeMethod, null, helloWorld, null);
         Console.WriteLine("MyClass.MyMethod returned: \"" + myObject + "\"");
      }
      catch( Exception e)
      {
         Console.WriteLine("Exception Caught "+e.Message);
      }
  }
}