FieldBuilder Class

Imports System.Reflection
Imports System.Reflection.Emit

Public Class Example
   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      ' Create an assembly.
      Dim myAssemblyName As New AssemblyName()
      myAssemblyName.Name = "DynamicAssembly"
      Dim myAssembly As AssemblyBuilder = _
         AppDomain.CurrentDomain.DefineDynamicAssembly(myAssemblyName, _
                                                AssemblyBuilderAccess.Run)
      ' Create a dynamic module in Dynamic Assembly.
      Dim myModuleBuilder As ModuleBuilder = myAssembly.DefineDynamicModule("MyModule")
      ' Define a public class named "MyClass" in the assembly.
      Dim myTypeBuilder As TypeBuilder = myModuleBuilder.DefineType("MyClass", _
                                          TypeAttributes.Public)

      ' Define a private String field named "MyField" in the type.
      Dim myFieldBuilder As FieldBuilder = myTypeBuilder.DefineField("MyField", _
                  GetType(String), FieldAttributes.Private Or FieldAttributes.Static)

      ' Create the constructor.
      Dim constructorArgs As Type() = {GetType(String)}
      Dim constructor As ConstructorBuilder = _
                  myTypeBuilder.DefineConstructor(MethodAttributes.Public, _
                           CallingConventions.Standard, constructorArgs)
      Dim constructorIL As ILGenerator = constructor.GetILGenerator()
      constructorIL.Emit(OpCodes.Ldarg_0)
      Dim superConstructor As ConstructorInfo = GetType(Object).GetConstructor(New Type() {})
      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.
      Dim myMethodBuilder As MethodBuilder = myTypeBuilder.DefineMethod("MyMethod", _
                        MethodAttributes.Public, GetType(String), Nothing)
      Dim methodIL As ILGenerator = myMethodBuilder.GetILGenerator()
      methodIL.Emit(OpCodes.Ldarg_0)
      methodIL.Emit(OpCodes.Ldfld, myFieldBuilder)
      methodIL.Emit(OpCodes.Ret)
      outputBlock.Text &= "Name: " & myFieldBuilder.Name & vbCrLf
      outputBlock.Text &= "DeclaringType: " & myFieldBuilder.DeclaringType.ToString() & vbCrLf
      outputBlock.Text &= "Type: " & myFieldBuilder.FieldType.ToString() & vbCrLf
      outputBlock.Text &= "Token: " & myFieldBuilder.GetToken().Token.ToString() & vbCrLf

      Dim myType As Type = myTypeBuilder.CreateType()
      ' Create an instance of the "HelloWorld" class.
      Dim helloWorld As Object = Activator.CreateInstance(myType, New Object() {"HelloWorld"})
      ' Invoke the "MyMethod" method of the "MyClass" class.
      Dim myObject As Object = myType.InvokeMember("MyMethod", _
                     BindingFlags.InvokeMethod, Nothing, helloWorld, Nothing)
      outputBlock.Text &= "MyClass.MyMethod returned: """ & myObject & """" & vbCrLf

   End Sub 
End Class 

using System;
using System.Reflection;
using System.Reflection.Emit;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // Create an assembly.
      AssemblyName myAssemblyName = new AssemblyName();
      myAssemblyName.Name = "DynamicAssembly";
      AssemblyBuilder myAssembly =
         AppDomain.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);
      outputBlock.Text += "Name: " + myFieldBuilder.Name + "\n";
      outputBlock.Text += "DeclaringType: " + myFieldBuilder.DeclaringType + "\n";
      outputBlock.Text += "Type: " + myFieldBuilder.FieldType + "\n";
      outputBlock.Text += "Token: " + myFieldBuilder.GetToken().Token + "\n";

      Type myType = myTypeBuilder.CreateType();
      // 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);
      outputBlock.Text += "MyClass.MyMethod returned: \"" + myObject + "\"" + "\n";
   }
}