Dynamic Asm Builder : Assembly Attributes « Assembly « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Assembly
3. Assembly Attributes

using System;
using System.Collections.Generic;
using System.Text;

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


  class Program
  {
    static void Main(string[] args)
    { 
      AppDomain curAppDomain = Thread.GetDomain();
      CreateMyAsm(curAppDomain);
      Assembly a = Assembly.Load("MyAssembly");

      Type hello = a.GetType("MyAssembly.HelloWorld");
      string msg = "asdf";
      object[] ctorArgs = new object[1];
      ctorArgs[0] = msg;
      object obj = Activator.CreateInstance(hello, ctorArgs); 
      MethodInfo mi = hello.GetMethod("SayHello");
      mi.Invoke(obj, null);
      mi = hello.GetMethod("GetMsg");
      Console.WriteLine(mi.Invoke(obj, null));
    } 
    public static void CreateMyAsm(AppDomain curAppDomain)
    {
      AssemblyName assemblyName = new AssemblyName();
      assemblyName.Name = "MyAssembly";
      assemblyName.Version = new Version("1.0.0.0");

      AssemblyBuilder assembly =curAppDomain.DefineDynamicAssembly(assemblyName,AssemblyBuilderAccess.Save);
      ModuleBuilder module = assembly.DefineDynamicModule("MyAssembly", "MyAssembly.dll");
      TypeBuilder helloWorldClass = module.DefineType("MyAssembly.HelloWorld",TypeAttributes.Public);
      FieldBuilder msgField = helloWorldClass.DefineField("theMessage", Type.GetType("System.String"),FieldAttributes.Private);

      Type[] constructorArgs = new Type[1];
      constructorArgs[0] = typeof(string);
      ConstructorBuilder constructor = helloWorldClass.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, constructorArgs);
      ILGenerator constructorIL = constructor.GetILGenerator();
      constructorIL.Emit(OpCodes.Ldarg_0);
      Type objectClass = typeof(object);
      ConstructorInfo superConstructor = objectClass.GetConstructor(new Type[0]);
      constructorIL.Emit(OpCodes.Call, superConstructor);
      constructorIL.Emit(OpCodes.Ldarg_0);
      constructorIL.Emit(OpCodes.Ldarg_1);
      constructorIL.Emit(OpCodes.Stfld, msgField);
      constructorIL.Emit(OpCodes.Ret);

      helloWorldClass.DefineDefaultConstructor(MethodAttributes.Public);

      MethodBuilder getMsgMethod = helloWorldClass.DefineMethod("GetMsg", MethodAttributes.Public, typeof(string), null);
      ILGenerator methodIL = getMsgMethod.GetILGenerator();
      methodIL.Emit(OpCodes.Ldarg_0);
      methodIL.Emit(OpCodes.Ldfld, msgField);
      methodIL.Emit(OpCodes.Ret);

      MethodBuilder sayHiMethod = helloWorldClass.DefineMethod("SayHello", MethodAttributes.Public, null, null);
      methodIL = sayHiMethod.GetILGenerator();
      methodIL.EmitWriteLine("Hello!");
      methodIL.Emit(OpCodes.Ret);

      helloWorldClass.CreateType();
      assembly.Save("MyAssembly.dll");
    }
  }