Create a callback that returns a value to its caller?

I am creating a class ("Class B") which is used by another class ("Class A") which instantiates it in VB.NET 3.5.

I would like Class B to read a value assigned to one of its properties by Class A every time an event happens in Class B.

However, I would like this property value to be dynamically assigned to the property by Class A when the event is fired in Class B.

I was thinking about somehow creating a delegate function in Class A that is linked to the property in Class B so that when the event is fired in Class B it would eventually invoke the delegate in Class A so that it returns a value to Class B.

I've been reading around delegates (that's how I arrived at the idea), but I am stu开发者_如何学编程ck on how to code this up - could someone please help with some skeleton code?

Also, I am not sure that this is the best approach for this - are there better solutions?

Thanks for your input.

I would probably isolate this from both classes a little. Maybe create a singleton that creates the value from Class A and just call that from Class B.

So

Public Class MySingleton

   'Singleton related code here

   Public Property MyDynamicValue As Integer

End Class

Then in Class A

Public Sub HandleClassBEvent(ByVal sender As Object, ByVal e As EventArgs) Handles ClassB.MyEvent
   MySingleTonInstance.MyDynamicValue = SetMyDynamicValue()
End sub

In Class B

   Public ReadOnly Property MyValueFromClassA Integer
      Get
           MySingletonInstance.MyDynamicValue
      End Get
   End Property