// File RTCG2.cs --- calling a static method with int argument and result
// sestoft@itu.dk * 2002

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

class RTCG2 {
  public static void Main(String [] args) {
    AssemblyName assemblyName = new AssemblyName();
    assemblyName.Name = "myassembly";
    // Build: run-only assembly
    AssemblyBuilder assemblyBuilder = 
      AppDomain.CurrentDomain.DefineDynamicAssembly(assemblyName,
                                                    AssemblyBuilderAccess.Run);
    // Build: module mymodule
    ModuleBuilder moduleBuilder = 
      assemblyBuilder.DefineDynamicModule("mymodule");
    // Build: public class MyClass { ... }
    TypeBuilder typeBuilder = 
      moduleBuilder.DefineType("MyClass", 
                               TypeAttributes.Class | TypeAttributes.Public, 
                               typeof(Object));
    // Build: public static int MyMethod(int x) { return x + 2; }
    MethodBuilder methodBuilder =
      typeBuilder.DefineMethod("MyMethod", 
                               MethodAttributes.Static | MethodAttributes.Public,
                               typeof(int),
                               new Type[] { typeof(int) });
    // Obtain an IL generator to build the method body
    ILGenerator ilg = methodBuilder.GetILGenerator();
    ilg.EmitWriteLine("MyClass.MyMethod() was called");
    ilg.Emit(OpCodes.Ldarg_0);
    ilg.Emit(OpCodes.Ldc_I4_2);
    ilg.Emit(OpCodes.Add);
    ilg.Emit(OpCodes.Ret);  
    Type ty = typeBuilder.CreateType();
    // Now call MyClass.MyMethod(5) using reflection:
    int res = (int)ty.GetMethod("MyMethod").Invoke(null, new object[] { 5 });
    Console.WriteLine(res);
    // Or create a delegate and call that instead:
    IntInt mm = (IntInt)Delegate.CreateDelegate(typeof(IntInt), 
                                                ty.GetMethod("MyMethod"));
    Console.WriteLine(mm(15));
  }

  public delegate int IntInt(int x);
}