designed for that. This removes the potential error to mix data and
function pointers.
Please note that I'm a little unsure how incorrect calls to the old
ctrl functions should be handled, in som cases. I currently return 0
and that's it, but it may be more correct to generate a genuine error
in those cases.
non-function pointers to function pointers and vice versa.
The current solution is to have unions that describe the
conversion we want to do, and gives us the ability to extract
the type of data we want.
The current solution is a quick fix, and can probably be made
in a more general or elegant way.
