vb.net Automation Issues - COM Interop

[SiJP]

I've been having a few issues recently in creating a vb.net class
library (using vs.net 2003), registering it for com interop and then
invoking its functions from an object in VB6.

The error I am receiving is happening in VB6 when I go to compile the
project:

Compile Error:
Function or Interface marked as restricted, or the function uses an
Automation type not supported in Visual Basic


Here is my vb6 code, which is run from a button on a test form:

Private Sub cmdInvoke_Click()
On Error GoTo err_handler

Dim obj As CommsClass.ClientInterface
Set obj = New CommsClass.ClientInterface

obj.Invoke

Exit Sub

err_handler:
MsgBox Err & " - " & Error

End Sub


And here is my vb.net CommsClass code. This is the ONLY code I have in
the project, and the project is registered for COM Interop.

Public Class ClientInterface
Public Function Invoke() As String
MsgBox("Hi")
End Function
End Class

Why would somthing so simply cause such an awkward error?!

Thanks

 

[Guest]

You have to make your classes visible to COM. Try the following code. Of
course, make sure you change the GUIDs by using the GUID generator utility.

Imports System.Runtime.InteropServices

<InterfaceType(ComInterfaceType.InterfaceIsIDispatch), _
Guid("A42C5454-6324-4be2-A7FE-A2868AE055DC")> _
Public Interface _ClientInterface

<DispId(1)> Sub Invoke()
<DispId(2)> Function GetSomeString() As String

End Interface

<ClassInterface(ClassInterfaceType.None), _
ProgId("CommsClass.ClientInterface"), _
Guid("1B6D1711-FD8A-4b34-A806-06B5EE45962E")> _
Public Class ClientInterface
Implements _ClientInterface

Public Function GetSomeString() As String Implements
_ClientInterface.GetSomeString

Return "Hello World From .NET"

End Function

Public Sub Invoke() Implements _ClientInterface.Invoke

MessageBox.Show("Message Box Invoked in .NET", ".NET Message Box",
MessageBoxButtons.OK, MessageBoxIcon.Information)

End Sub

End Class

 

[SiJP]

Thanks rmacias, I have a play with this tomorrow.

I only went the route I did (without the COM exposure) becuase I have
sucessfully done this in the past and used late binding within my vb6
application to access the functions on the .net dll.

.... to be continued