Structure Nullable2(Of T As Structure)
 
    Private a As T?
 
    Sub New(ByVal w As T)
      a = w
    End Sub
 
    Sub New(ByVal w As T?)
      a = w
    End Sub
 
    Shared Widening Operator CType(ByVal w As T) As Nullable2(Of T)
      Return New Nullable2(Of T)(w)
    End Operator
 
    Shared Widening Operator CType(ByVal w As T?) As Nullable2(Of T)
      Return New Nullable2(Of T)(w)
    End Operator
 
    Shared Narrowing Operator CType(ByVal w As Nullable2(Of T)) As T
      Return w.a.GetValueOrDefault
    End Operator
 
    Shared Narrowing Operator CType(ByVal w As Nullable2(Of T)) As T?
      Return w.a
    End Operator
 
  End Structure

    Dim a As Nullable2(Of Integer)
 
    Dim b As Integer
    a = 4
    b = a 'b = 4
    a = Nothing
    b = a 'b = 0
 
    Dim c As Integer?
    a = 6
    c = a 'c = 6
    a = Nothing
    c = a 'c = Nothing
 
    a = b 'a = 0
    a = c 'a = Nothing