"דני" <da***@si-eng.co.il> wrote in message
news:9F1ED679-860F-4607-9A0C-9CF379A1F1F5@microsoft.com...
>   Public Class Form1
>        Public Class a
>
>        End Class
>        Public Class a1
>            Inherits a
>        End Class
>        Public Class a2
>            Inherits a
>            Private dsfs As d(Of c2) 'err Error 1 Type argument 'c2' does
> not inherit from or implement the constraint type 'b(Of a)'.
>
>        End Class
>        Public Class b(Of T As a)
>
>        End Class
>
>        Public Class c
>            Inherits b(Of a)
>
>        End Class
>        Public Class c1
>            Inherits b(Of a)
>
>        End Class
>        Public Class c2
>            Inherits b(Of a1)
>
>        End Class
>        Public Class c3
>            Inherits b(Of a2)
>
>        End Class
>        Public Class d(Of T As b(Of a))
>
>        End Class
>        Dim r As New d(Of c3) 'err Error 1 Type argument 'c2' does not
> inherit from or implement the constraint type 'b(Of a)'.
>
>        Dim r1 As New d(Of c) 'ok
>
>    End Class