>> C# Begin >>>>>>>>>>>>>>>

> Hello,
>
> I have a class in C# with events, which is exposed as a COM-object.
> When I have a VB6 Client that is using this class, I see that
> eventhandlers are not removed, when VB releases the com object.
>
> I'm using VS2005, but it seems that the behaviour is the same with VS2003
>
> Is there something wrong with the way I'm using this, or may it be that
> this is an error with NET or VB?
> It doesn't seem to be related to the garbage collector, because when I
> call GC.Collect(), remove doesn't get called either.
>
> Thanks in advance
> Sascha
>
>
> Here is my code
>
> C#:
> Register for COM interop has to be enabled
>
>>> C# Begin >>>>>>>>>>>>>>>
> using System;
> using System.Runtime.InteropServices;
> using System.Diagnostics;
>
> namespace NetComLib
> {
> // delegate definition
> [ComVisible(false)]
> public delegate void ChannelChangedDelegate(int channel);
>
> // Event-Interface
> [ComVisible(true)]
> [Guid("30BBBC2F-03E0-497c-82BF-93B1D775B794")]
> [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
> public interface INetComLibEvents
> {
> void ChannelChanged(int channel);
> }
>
> // Interface
> [ComVisible(true)]
> [Guid("0EB15C71-DF7B-46e3-8686-2A7708D9487A")]
> [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
> public interface INetComLib
> {
> void SetChannel(int channelNo);
> }
>
> // COM-object
> [ComVisible(true)]
> [ProgId("Test.NetComLib")]
> [Guid("C2D2CE9B-09A6-475e-A839-C8F90C630F43")]
> [ClassInterface(ClassInterfaceType.None)]
> [ComSourceInterfaces("NetComLib.INetComLibEvents")]
> public class NetComLib : INetComLib
> {
> public void SetChannel(int channelNo)
> {
> if (channelChanged != null)
> channelChanged(channelNo);
> }
>
> private event ChannelChangedDelegate channelChanged;
>
> public event ChannelChangedDelegate ChannelChanged
> {
>
> [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.Synchronized)]
> add
> {
> this.channelChanged += value;
> Trace.WriteLine("Eventhandler added");
> }
>
> [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.Synchronized)]
> remove
> {
> this.channelChanged -= value;
> Trace.WriteLine("Eventhandler removed");
> }
> }
> }
> }
> << C# End <<<<<<<<<<<<<<<<<
>
> And here is the code of my VB-Form with one button
>
> << VB Begin <<<<<<<<<<<<<<<
> Dim WithEvents comLib As NetComLib.NetComLib
> Dim i As Integer
>
>
> Private Sub comLib_ChannelChanged(ByVal channel As Long)
> MsgBox channel
> End Sub
>
> Private Sub Command1_Click()
> If comLib Is Nothing Then
> Set comLib = New NetComLib.NetComLib
> comLib.SetChannel i
> i = i + 1
> Else
> Set comLib = Nothing
> End If
> End Sub
> << VB End <<<<<<<<<<<<<<<<<
>