Re: Arbitrary function: find the number(s) of expected arguments

[Michael Heerdegen]

Eli Zaretskii <address@hidden> writes:

> > > I disagree with this conclusion.  The fact is that the Emacs Lisp
> > > interpreter does know how to produce a clear answer.
> > 
> > Imagine `f' accepts, say, three arguments.  Now, let's
> > 
> > (advice-add 'f :around
> >             (defun my-f-around-advice (orig-f &rest args)
> >               (let ((some-value (g args)))
> >                 (if (function-p (car-safe some-value))
> >                     (apply (car some-value) (cdr some-value))
> >                   (if (h args)
> >                       (k args)
> >                     (apply orig-f some-value))))))
> > 
> > What should (function-arity #'f) return?
>
> How is that relevant to the cited text?

I had concluded that it is not possible to implement `function-arity' so
that it will always give a meaningful return value.  You disagreed
(that's the cited text), so I tried to give an example proving my
conclusion.  What did I miss?


Michael.