.net COMVisible/ComInterop - can you use a type without registering it?

Question

My first attempts at this have failed but I'm hoping it is possible. If I have a class like this that is COM registered:

[ComVisible(true)]
public interface Resolver
{
    object Resolve(string type);
}

[ProgId("ClassResolver")]
[ClassInterface(ClassInterfaceType.None)]
[ComVisible(true)]
[Guid("53DB4409-0827-471D-94CE-2601D691D04C")]
public class Class1:Resolver
{
    public object Resolve(string type)
    {
        return (ClassLibrary2.Interface1) new ClassLibrary2.Class1();
    }
}

Can I use it to return Class2.Interface1 which is ComVisible but not registered (it's in a different library):

[ComVisible(true)]
public interface Interface1
{
    string SomeMethod();
}


public class Class1:Interface1
{
    public string SomeMethod()
    {
        MessageBox.Show("SomeMethod");
        return "SomeMethod";
    }
}

My first attempts have returned the error: IUnknown:SomeMethod (No exported method), but I'm hoping there might be some trick to doing this that I don't know.

Answer 1

I found this is possible if you mark the class as ComVisible (just the interface as ComVisible wasn't enough). I can now use ClassLibrary3 via COM. See below code:

namespace ClassLibrary1
{
[ComVisible(true)]
public interface Resolver
{
    object Resolve(string type);
}

[ProgId("ClassResolver2")]
[ClassInterface(ClassInterfaceType.None)]
[ComVisible(true)]
[Guid("83720331-12CB-48E1-947C-2413F7B9AB89")]
public class Class1:Resolver
{
    public object Resolve(string type)
    {
        return new ClassLibrary3.Class1();
    }
}
}

Totally separate library that was not "Regasm"ed:

namespace ClassLibrary3
{

[ComVisible(true)]
public class Class1 
{
    public string SomeMethod()
    {
        MessageBox.Show("ClassLibrary3.Class1.SomeMethod....");
        return "ClassLibrary3.Class1.SomeMethod";
    }
}
}