dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, Nov 05, 2009 at 12:14:36AM +0100, Marie Rognes wrote:
> Anders Logg wrote:
> > On Wed, Nov 04, 2009 at 01:10:17PM +0100, Johan Hake wrote:
> >
> >> On Wednesday 04 November 2009 09:37:55 Garth N. Wells wrote:
> >>
> >>> kent-and@xxxxxxxxx wrote:
> >>>
> >>>> Hi, I am very happy with the  Expression, but old code like
> >>>>
> >>>> class Dabla(Function):
> >>>>     def eval(...)
> >>>>
> >>>> still works.
> >>>>
> >>>> The only problem is that the function is zero even though eval is
> >>>> implemented. Is it
> >>>> possible to turn this old code into an error?
> >>>>
> >>> In C++, no. There is no mechanism in C++ to prevent a user overloading
> >>> or hiding a member function.
> >>>
> >> In Python, using meta classes, yes.
> >>
> >> This is a nice exercise for those of you who want to get to know meta classes
> >> in Python. ;) If and when I have time I can fix this. (Heading for the states
> >> next Tuesday)
> >>
> >> Should we allow sub-classing of Function, but not overloading of eval?
> >>
> >
> > We could start by disallowing subclassing the Function class and then
> > if a time comes when someone wants to subclass it, we can rethink it.
> >
> >
>
>
> Nooo! (Someone(tm) wants to subclass it already.)

ok, so let's rethink this. :-)

Is it worth the effort to disallow overload of eval?

--
Anders

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