Hi Rene,
Thanks for your prompt reply. Maybe I did not make myself clear or it is
quite likely that I am missing something in your answer. I realise that I can
extend the functionality of TMaterial by deriving a class from it, called,
say, TMedium. What I would like to do is to be able to access objects of
type TMedium * from the global pointer, gGeometry, e.g., I would like to
be able to use the equivalent of gGeometry->GetMaterial("whatever") to get
a pointer to a TMedium * that I can then use to get at the properties of the
medium. What would be the easiest way to do that? Derive new classes from
TGeometry and TROOT, or what?
Regards,
Gora