Creating a subclass instance from a base class instance

[Larry Lard]

[formerly posted to ms.public.dotnet.vb.general, but this seems to be a
much higher traffic group]

Hi,

This seems to me like a problem that has a simple solution but I can't
for the life of me work it out.

Suppose I have a base class Employee

Public Class Employee
Public FullName As String
....
End Class

and from it I define the derived subclass Supervisor

Public Class Supervisor
Inherits Employee

Public MaxTeamMembers As Integer
....
End Class
Suppose now I have an employee

Dim e As Employee

who has been made a supervisor. I want to create a Supervisor object s
with all the Employee properties copied from e. I thought of making a
constructor like this in Supervisor:

Public Sub New(fromEmployee As Employee)
MyBase().New

Me.FullName = fromEmployee.FullName
End Sub

but that would break if Employee was ever changed to have more
properties (also in my real app the base class has LOTS of properties).
I thought I might be able to do something like

Public Sub New(fromEmployee As Employee)
MyBase().New

MyBase = fromEmployee ' oh no you can't
End Sub

but I can't. The very first thing I tried was just casting an As
Employee variable to Supervisor, but it wouldn't let me - after some
thought I now understand that it is correct.

What is the proper way to do what I want?
Thanks,

--
Larry Lard
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