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
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