Re: Why does Octave ignore additional input arguments ?

[Julien Bect]

Le 09/02/2016 11:29, John W. Eaton a écrit :
> On 02/09/2016 04:11 AM, Colin Macdonald wrote:
> > On 08/02/16 23:56, Julien Bect wrote:
> > > but I find it annoying (and I would be perfectly happy with a default
> > > non-customized error message).
> >
> > +1 for annoying.
> >
> > I hadn't paid attention to this problem until recently; *not* looking
> > forward to doing this everywhere:
> >
> > if (nargin > ...)
> >    print_usage ();
> > endif
>
> I think it would be fairly easy to make exactly that happen 
> automatically.
>
> The question is whether there is some legitimate reason to keep the 
> existing behavior.  I'm not convinced that there is, but maybe I'm 
> wrong?  It would help me if I see an example of where the current 
> behavior is useful.

I think that essentially two reasons have been invoked to justify 
keeping the existing behavior :

1) The existing behavior makes it possible to issue customized error 
message when nargin > nargin_max.

2) In a situation where a package requires its users to provide a handle 
to a function, say F(x), and then decides to extend the interface with 
an additional argument, say F(x, y), the existing behavior makes it 
possible for the package developer to switch to the new interface 
unconditionally, without requiring the user to modify its own functions.

For the first point there isn't much to say except that, as I said 
earlier, I would be perfectly happy with a default error message for 
this.  I am not aware of a situation where a customized error message is 
really needed.

For the second point, Olaf Till had an example involving the optim 
package.  See 
http://lists.gnu.org/archive/html/help-octave/2009-08/msg00074.html.

Carlo de Falco has proposed a try-catch based solution to Olaf's 
problem, which I think is fine: 
http://lists.gnu.org/archive/html/help-octave/2009-08/msg00077.html 
(especially if the error is accompanied with an error identifier that 
makes it possible to deal with it cleanly).

But Olaf seemed to think to the try-catch approach wouldn't do: 
http://lists.gnu.org/archive/html/help-octave/2009-08/msg00078.html.

@++
Julien