Re: check argument count in defcustom :safe?

[Stefan Monnier <monnier@IRO.UMontreal.CA>]

>   :safe  'functionp)

FWIW, I think it makes absolutely no sense for :safe to be `functionp'.
This is just a gaping security hole.  And checking the number of
arguments would make no difference in this respect.

> but I don't see any way to access the argument count from lisp.  Am I
> missing something?

The number of arguments passed to a function is something that can be
easily checked by the function, but checking the number of arguments
accepted by a function is generally impossible (think of a function like

   (lambda (&rest args)
     (if (> (length args) (if (halting-p (car args)) 2 3))
         (signal 'wrong-number-of-arguments 'foo (length args)))
     ...)


-- Stefan