Paul,

Ayour suggestion does almost exactly what I want, however there seems to
be another solution, which I discovered (*embarrassed*) by accident: Nested
Classs.

Class Customer
'stuff here like Name etc

friend class Orders
'stuff here for orders
end class

end Class

By the above, I can actually limit completely the ability for clients to
dimension the class let alone try to instansiate it!

Thanks for your help
Robert

"Paul Mc" <paulmc@nospam.thehub.com.au> wrote:
>
>G'day Robert.
>
>>I've had a play with .NET and perused MSDN, however I can't seem to find
>>a way to achieve the same result (class heirarchy). Keeping in mind that
>>I do not wish to allow clients to directly access the "SomeSubClass", but
>>rather only via its super.
>
>OK there are a few things to think about here.
>
>First, you need the Child class - call it cOrders - to be declared public.
>That way, clients will be able to use the class.
>
>So, we have
>
>Public Class cOrders
>End Class
>
>Second, you want cOrders to be a child of the Parent class - call it cCustomer
>- and only anstantiable via friend access.
>
>So, now we have:
> Public Class cOrders
> Friend Sub New()
> 'Initialise stuff
> End Sub
> End Sub
>
>The Public scope of tyhe class allows clients to read and use the cOrders
>class, however the Friend scope of your Instantiator (ie Sub New) means
that
>only objects in your assembly can instantiate it. Thus, if you are creating
>a DLL for instance, clients that reference your DLL will *not* be able to
>get an instance of cOrders without you supplying a method having a return
>type of cOrders.
>
>Now, this does *not* limit the cOrders class to instantiation via one specific
>"Parent" class - say, cCustomer. To do that, things will need to be a bit
>more tricky - the first option that springs to my mind (hopefully someone
>out there chimes in with a more elegant solution) works on the following
>theory:
>
>Nest the child class (cOrders) so it has access to private members of the
>parent (cCustomer).
>
>In the parent have some private flag/token letting the child know if it
is
>OK to instantiate.
>
>Here is an example implementation:
>
>Public Class cCustomer 'The Parent class
> Private mbToken As Boolean = False
> Private mOrders As cOrders
>
> Public ReadOnly Property Order() As cOrders
> Get
> If mOrders Is Nothing Then
> mbToken = True
> mOrders = New cCustomer.cOrders(Me)
> mbToken = False
> End If
>
> Return mOrders
> End Get
> End Property
>
> Public Class cOrders ' Child class is now nested
> Friend Sub New(ByRef Customer As cCustomer)
> If Not Customer.mbToken Then
> Throw New ApplicationException("Orders Class May Only Be Instantiated
>From Customer Instance")
> Exit Sub
> Else
> 'Initialise stuff
> End If
> End Sub
> End Class
>End Class