Re: Too many arguments?

[Olaf Till]

On Wed, Aug 05, 2009 at 10:23:22PM -0400, John W. Eaton wrote:
> I don't remember exactly why I chose to make Octave silently accept
> extra arguments.  Maybe I didn't have an easy way to implement this
> feature at the time.
> 
> In any case, some people might think this difference with Matlab is a
> minor bug.  It would probably not be hard to make Octave generate an
> error in this case, so it might happen in the future.  If you don't
> want that, then can you explain clearly why it makes sense for Octave
> to silently accept extra arguments that are not used?

Because then a function can be called with some extra last arguments,
no matter whether the called function has listed them in its
header. This makes sense if it can vary which function is called,
e.g. if the function to be called is configurable. If extra arguments
do not cause an error, one can change the interface of the function
call at the caller side without changing each existing called
function.

Example: In Octave-Forge, for main/optim/leasqr.m the user has to
supply a user-function and may supply a second function to compute its
Jacobian. If the user doesn't supply the latter, a generic function is
used to estimate the Jacobian with difference quotients (dfdp.m). Now
I would like to introduce maximal or minimal values for parameter
estimation into leasqr.m. These maximal or minimal values should for
some reason also be respected by dfdp.m. So I would like to pass an
additional argument which contains the maximal or minimal values from
leasqr.m to dfdp.m. But users may already have used leasqr.m before
with their own Jacobian-functions, which do not have the extra
argument in the interface (and BTW probably do not need to honour it
anyway, since they do not compute difference quotients). If Octave
does not accept extra arguments, these users have to change the
interface of their functions after the interface-change in leasqr.m.

Olaf