Re: [Chicken-users] Bug with #!optional in Chicken 4.8.0

[Jörg F . Wittenberger]

On Oct 14 2012, Felix wrote:

> From: John Croisant <address@hidden>
> Subject: [Chicken-users] Bug with #!optional in Chicken 4.8.0
> Date: Sat, 13 Oct 2012 20:34:26 -0400
>
> > In Chicken 4.8.0, procedures defined with #!optional no longer signal
> > an exception if invoked with too many arguments. For example:
> >
> > (define (foo x #!optional y) (list x y))
> > (foo 'x 'y 'too 'many 'args)
> >
> > In Chicken 4.7, this would signal an exception, because the foo
> > procedure expects a maximum of 2 arguments. In Chicken 4.8, the extra
> > arguments are simply ignored.
> >
> > I think this is a bug, because the docs for "Extended DSSSL style
> > lambda lists" say:
> >
> > > If there is no rest-parameter  and no keyword-parameters in the
> > > parameter-list, then it shall be an error for any extra arguments to
> > > be passed to the procedure.
>
> That is correct. The check has been removed and conflicts with
> the documentation. I will update the docs accordingly. 
>
> The check has been removed to accomodate a terrible hack for handling
> re-initialization of parameters with "parameterize", and for a slight
> performance win. The hack is so terrible, I hardly dare to talk about
> it in public.

I'm afraid go disappoint you Felix. But thats exactly the kind of hack
some (like me) love to learn about.

Not as a papparazzi and certainly not in doc, which are ever updated.
But there is much more go learn from a dirty (intermediate) hack explained
than a thousend "best practice examples as working".

> On the other hand, I see no problem in allowing extra
> parameters to lambdas with rest/optional arguments being silently
> dropped - it has been done before.
>
>
> cheers,
> felix
>
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