dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Martin Sandve Alnæs wrote:
> 2008/4/13, Garth N. Wells <gnw20@xxxxxxxxx>:
> > In the down casting functions in GenericTensor, what's the difference
> >  between
> >
> >    T* t = dynamic_cast<T*>(instance());
> >
> >  and
> >
> >    T* t = dynamic_cast<T*>(this);
> >  ?
>
>
> // Assume this is configured to use a PETScVector:
> GenericVector * v = new Vector();
>
> // This won't work:
> PETScVector * pv = dynamic_cast<PETScVector*>(v);
>
> // This will work (and is what down_cast does):
> PETScVector * pv = dynamic_cast<PETScVector*>(v->instance());
>
> This was the only intended usage for instance().

OK. Thanks!

Garth

> >  Is there much overhead associated with a dynamic cast?
> >
> >  Garth
>
> I have no idea how much overhead there is, but I'm assuming it won't
> be placed in inner loops anyway.
>
> --
> Martin