Question

I have some very simple code to generate an assembly and invoke a method on a contained type. The method gets called and runs correctly, however when I view the generated assembly using Reflector, I don’t see the type.

Below is the sample code:

namespace ConsoleApplication2 {     class Proggy     {         public static void Main(string[] args)         {             var ab = AppDomain.CurrentDomain.DefineDynamicAssembly(                 new AssemblyName() { Name = 'MyAssembly' },                 AssemblyBuilderAccess.RunAndSave);             var module = ab.DefineDynamicModule(ab.GetName().Name);             var typeBuilder = module.DefineType('MyType');             var ctr = typeBuilder.DefineConstructor(MethodAttributes.Public,                  CallingConventions.Standard, Type.EmptyTypes);             var ilgc = ctr.GetILGenerator();             ilgc.Emit(OpCodes.Ldarg_0);             ilgc.Emit(OpCodes.Call, typeof(object).GetConstructor(Type.EmptyTypes));             ilgc.Emit(OpCodes.Ret);             var method = typeBuilder.DefineMethod('MyMethod', MethodAttributes.Public,                 typeof(int), new[] { typeof(string) });             var ilg = method.GetILGenerator();             ilg.Emit(OpCodes.Ldarg_1);             ilg.EmitCall(OpCodes.Callvirt, typeof(string).GetProperty('Length').GetGetMethod(),                 null);             ilg.Emit(OpCodes.Ret);             var type = typeBuilder.CreateType();             ab.Save('mytestasm.dll');             var inst = Activator.CreateInstance(type);             Console.WriteLine(type.InvokeMember('MyMethod', BindingFlags.InvokeMethod, null, inst,                 new[] { 'MyTestString' }));             Console.ReadLine();         }     } } 

and here is the corresponding disassembly from Reflector:

.assembly MyAssembly {     .ver 0:0:0:0     .hash algorithm 0x00008004 } .module RefEmit_OnDiskManifestModule // MVID: {0B944140-58D9-430E-A867-DE0AD0A8701F} // Target Runtime Version: v2.0.50727 

… and …

{     .class private auto ansi <Module>     {     } } 

Can anyone help me with getting the assembly properly saved?

Answer 1

The trick is to use a ‘persistable module’ version of DefineDynamicModule method on the AssemblyBuilder instance. That is, instead of:

var module = ab.DefineDynamicModule(ab.GetName().Name); 

use something like:

var module = ab.DefineDynamicModule(ab.GetName().Name, ab.GetName().Name + '.mod'); 

Thereafter the corresponding module appears in the assembly after saving.