Imports System

​

Public Module Module1

    Public Sub Main()

        Dim a As New A()

        Dim b As New B()

​

        a.F = New X()

        b.F = New Y()

        Dim c As New Container()

        c.Value = a

        Console.WriteLine(c)        

        c.Value = b

​

        Console.WriteLine(c)        

    End Sub

End Module

​

Public Class Container

    Public Value As A

    Public Overrides Function ToString() AS String

        Return Value.ToString()

    End Function

End Class

​

Public Class X

    Public Overrides Function ToString() AS String

        Return "X"

    End Function

End Class

​

Public Class Y

    Inherits X

    Public Overrides Function ToString() AS String

        Return "Y"

    End Function

End Class

​

​

Public Class A

    Public Overridable Property F As X

    Public Overrides Function ToString() AS String

        Return "A" + F.ToString()

    End Function

End Class

​

Public Class B

    Inherits A

    Public Shadows Property F As Y

    Public Overrides Function ToString() AS String

        Return "B" + F.ToString()

    End Function

End Class

​

​

​