Re: Arguing for a nilp function and where to put it

[Eli Zaretskii <eliz@gnu.org>]

> From: Pedro Andres Aranda Gutierrez <paaguti@gmail.com>
> Date: Sat, 1 Apr 2023 07:37:44 +0200
> 
> Use case for a nilp function:
> 
> I have a buffer-local variable with a default value, and I want to
> allow to (silently) set it to nil (and only to nil) from
> .dir-locals.el or Local Variables.
> 
> Currently I have
> 
> (defun nilp(v) (unless v t))
> 
> and I use it with
> 
> (put '<variable> 'safe-local-variable #'nilp)
> 
> which is much cleaner than
> 
> (put '<variable> 'safe-local-variable (lambda (p) (unless p t)))
> 
> every time I need it. I think other people may benefit from having
> this simple function as part of Emacs and I'm not sure whether the
> elisp form would be better than something more lower level like
> integerp and in which file it would reside best.

Why cannot you use the existing function 'null'?

If 'null' doesn't fit the bill, please explain why.