XmlSerializer.Deserialize factory method?

[Craig Buchanan]

I have an Application object that i use to open saved instances of a variety
of derived classes (a factory method). Each derived-class instance is based
on a MustInherit base class. Here's a code snippet:

Public Function Open(ByVal source As String) As MyBaseClass
...

Dim XS As XmlSerializer = New XmlSerializer(GetType(MyBaseClass))

'error on this statement if i use GetType(MyBaseClass); no error if i
use GetType(MyDerivedClass)
Return XS.Deserialize(SR)

...
End Function

The Xml is generated by a Save method in MyBaseClass:

Public Sub SaveAs(ByVal destination As String)
....
Dim XS As XmlSerializer = New XmlSerializer(Me.GetType)
XS.Serialize(SW, Me)
....
End Sub

Obviously, i would like my factory method to correctly identify what type of
object has beeen saved then reconstitue it. I suppose i could bury the
class name and assembly in the xml, then use that to create the correct type
manually, but this approach doesn't seem to be very elegant.

can someone suggest a better approach?

thanks a lot,

Craig Buchanan