"Michael Shishkin" wrote:

> Looking for help with non-COM C++ interfaces implementation. I can’t
> find any reference on how to implement / use non-COM C++ interfaces in C#.
>
> I have an application that uses COM interfaces from one of the Microsoft
> services and have no problems using those. However, there are few
> interfaces in this service defined as (C++ (not COM) interface)
> regarding Microsoft documentation on this service API, also these
> interfaces inherit the methods of the standard COM interface IUnknown
> (same source).
>
> Making story short, I can successfully call method that returns IntPtr
> to the non-COM interface with reasonable pointer value, even
> Marshal.QueryInterface works fine and returns proper pointer. My problem
> is how to define C# wrapper for this type of interface, looks like
> standard way that COM likes, does not work for me.
>
> [ComVisible(false),
> ComImport,
> InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
> Guid("E561901F-03A5-4afe-86D0-72BAEECE7004")]
> public interface IProviderNotifications
> {
> [PreserveSig()]
> uint OnLoad([MarshalAs(UnmanagedType.IUnknown)] object pCallback);
>
> [PreserveSig()]
> uint OnUnload(int bForceUnload);
> }
>
>
> I tried “Marshal.GetObjectForIUnknown” on returned IntPtr, it just
> throws an exception (No such interface) even without me trying to cast
> it to specific type. I also tried “Marshal.PtrToStructure” and define my
> wrapper class not as interface but as abstract class (blowup with
> exception “Cannot create an abstract class”, reasonable).
>
> I hope someone know anything about this issue, any help, suggestion,
> hint greatly appreciated. I really stuck now.
>
> Thanks.