dolfin team mailing list archive

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

On Mon, 2010-08-02 at 10:33 +0200, Anders Logg wrote:
> On Sun, Aug 01, 2010 at 06:35:22PM +0100, Garth N. Wells wrote:
> > On Sun, 2010-08-01 at 12:40 +0200, Florian Rathgeber wrote:
> > > -----BEGIN PGP SIGNED MESSAGE-----
> > > Hash: SHA1
> > >
> > > Hi,
> > >
> > > When using GenericTensor::down_cast() for a tentative down cast it would
> > > be helpful if it would throw std::bad_alloc (as any dynamic_cast would
> > > do)
> >
> > Do you mean std::bad_cast?
> >
> > > instead of invoking dolfin::error. Currently you would have to catch
> > > std::runtime_error and check what() to distinguish a failed cast from
> > > another dolfin::error, which is pretty inconvenient. Is there a specific
> > > reason why it is implemented this way?
> > >
> >
> > Not really.
> >
> > It's not too clear to me what you'd like. Would you prefer that
> > down_cast doesn't throw an error, but leave it up to the programmer to
> > check that a cast was successful, or just that DOLFIN catch a
> > std::bad_cast and print more information before throwing an error?
> 
> I think the best would be if DOLFIN caught the error, then wrote an
> informative message (since it knows exactly what went wrong) and then
> threw bad_cast.
> 

Looks like there isn't much that can be done - std::bad_cast is only
thrown when casting references, not pointers (as we do internally). From
what I've read, our way of checking for a null pointer is correct.

Garth

> --
> Anders