use class factory to set required class variables?

[Alan]

On Jan 26, 4:37 pm, Alan <alan.is... at gmail.com> wrote:
> I have a class factory ``f``` that subclasses ``A`` *only* in
> order to define the class variables.

I suppose it would be clearer to say that `f` *returns*
subclasses of `A`.  Hopefully that was clear ...

Alan Isaac