[2008] Call parent function from DLL

[JacquesLebrun]

I have a bunch of VB.NET programs that have a general purpose logging function to log events, errors, exceptions, etc. It looks like this:

Sub LogMe(Msg as string)
   LstLog.items.add(now.tostring & " " & Msg)
End Sub

I wrote a few VB.NET DLLs that contain classes used my my VB.NET programs. In thoses DLL classes, I would like to also trap some events, errors, exceptions, etc. But I want them to be logged using my main LogMe function. Here is some pseudo-code of what I was looking for:

' Main program code

imports MyLib

' Initialize program
Private Sub FrmMain()
   FrmMain.Show
   FrmMain.LstLog.Clear
   MyLib.InitCallBack(Address_of_LogMe)
End Sub

' Log message to ListBox
Sub LogMe(Msg as string)
   LstLog.items.add(now.tostring & " " & Msg)
End Sub

' DLL library code

Public Module Globals

Private PointerLogMe as ??? = nothing

' Initialize Call Back function by main program
Public Sub InitCallBack(AddressLogMe as ???)
   PointerLogMe = AddressLogMe
End Sub

' Local logging function that actually does the CallBack to the main program
Private Sub LocalLogMe(Msg as string)
   If not PointerLogMe is nothing Then
      Call_function_stored_inPointerLogMe_with_Msg_as_a_parameter
   End if
End Sub

...
LocalLogMe("An exception was detected in function XXX")
...

End Module

I assume I will need to define Delegates to save my LogMe fonction pointer, but after a lot of Googling, I was not able to figure out how to code this.

Thanks