Utilisation des Custom Events afin de créer une relation "Friend" comme C++.
  

    
      Public Delegate Sub MyDelegate()
Public Class MyClass1
   Public Custom Event MyEvent As MyDelegate
      ' Called when a class want to subscribe to the event
      AddHandler(ByVal value As MyDelegate)
         ' Accept the handler only if it comes from a certain class
         If value.Target.GetType() Is GetType(MyClassObserver) Then
              MyEventHandler.Add(value)
         Else
              Throw new ArgumentException("Your class is not authorized to handle any event of this one.")
         End
      End AddHandler
      ' Called when a class want to unsubscribe to the event 
      RemoveHandler(ByVal value As MyDelegate)
         MyEventHandler.Remove(value)
      End RemoveHandler
      ' Called when the event is triggered
      RaiseEvent()
         On error resume next
         For Each D as MyDelegate in MyEventHandlers : D() : Next
      End RaiseEvent
   End Event

   Private MyEventHandlers as new List(Of MyDelegate)

End Class