Help creating interface.

[Scott.Macmaster]

This seems like a very unusually requirement and probably a bad design. If you give some more details I could suggest a better alternative. In the meantime I have a suggestion for adding all instances to a global variable. However, there are 2 major issues with this. Someone could create a local instance of the global object. Also, this would result in major memory leaks if you aren't careful about removing references to unused instances of the objects you are tracking.

    Public Class Tracker

        Private Instances As List(Of SpecialClass)

        Public Sub Add(ByVal obj As SpecialClass)
            Instances.Add(obj)
        End Sub

    End Class

    Public Class SpecialClass

        Private Sub New()
        End Sub

        Public Shared Function GiveMeANewOne(ByVal tracker As Tracker) As SpecialClass
            Dim obj As New SpecialClass()
            tracker.Add(obj)
            Return obj
        End Function

    End Class

If you implement ths in a dll you should be able to prevent creation of local Trackers. However, you still have the issue of memory leaks.