Hi Nick,

problem is that I only have a base class object which I need to *cast* to a
derived object. So, basically, my situation is something like this:

  MyBaseClass mbc = new MyBaseClass(..., ..., ..., ...);
  MyTypedClass mtc = (MyTypedClass)mbc;    // throws InvalidCastException

Disturbing part: MyTypedClass doesn't add any fields, so the cast ist
perfectly safe.

When I have VS2003 create a typed DataSet using an xsd, it does the same,
but there it works:

 public class UsersRow : DataRow
 {
   ...

   public UsersRow NewUsersRow()
   {
     return ((UsersRow)(this.NewRow()));    // NewRow() returns a DataRow;
   }

   ...
 }

Disturbing part II: UsersRow in fact *adds* new fields to DataRow. Why does
it work?

To get more into detail, cloning would yield a huge overhead. MyBaseClass is
a tree object having a collection of MyBaseClass children. I don't create it
using a constructor, instead I use a static factory function to create a
whole tree of objects and return only the root:

  MyBaseClass mbc = MyBaseClass.CreateHierarchy(..., ..., ..., ...);
  MyTypedClass mtc = (MyTypedClass)mbc;    // throws InvalidCastException

MyBaseClass is based in a separate Common project, therefore it is untyped,
i.e. only provides properties through a [] operator (in fact it forwards the
operator to a private DataRow member).

In my object I now want to provide typed access to each of the properties,
like

 string Street    {    get    {return base["Street"];}}

That's why I need the cast. It's basically the same methodology like with
MS' typed DataSets.

Any quick help is highly appreciated!!!

TIA,
Axel Dahmen

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