From: Michael Albinus <michael.albinus@gmx.de>
To: Pedro Andres Aranda Gutierrez <paaguti@gmail.com>
Cc: emacs-devel <emacs-devel@gnu.org>
Subject: Re: Arguing for a nilp function and where to put it
Date: Sat, 01 Apr 2023 08:07:30 +0200 [thread overview]
Message-ID: <87jzywcezh.fsf@gmx.de> (raw)
In-Reply-To: <CAO48Bk_E7XSLB7X_Q8T5M7gifUBF=-50cGUNjRfVLbkhVyRykg@mail.gmail.com> (Pedro Andres Aranda Gutierrez's message of "Sat, 1 Apr 2023 07:37:44 +0200")
Pedro Andres Aranda Gutierrez <paaguti@gmail.com> writes:
Hi Pedro,
> 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.
There is the `null' function, which is what you need.
> /PA
Best regards, Michael.
next prev parent reply other threads:[~2023-04-01 6:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-01 5:37 Arguing for a nilp function and where to put it Pedro Andres Aranda Gutierrez
2023-04-01 6:01 ` tomas
2023-04-01 6:07 ` Michael Albinus [this message]
2023-04-01 6:10 ` Eli Zaretskii
2023-04-01 7:09 ` Pedro Andres Aranda Gutierrez
2023-04-02 21:28 ` Roland Winkler
2023-04-03 3:02 ` Richard Stallman
2023-04-03 3:34 ` Emanuel Berg
2023-04-03 12:46 ` Andreas Schwab
2023-04-03 18:48 ` Roland Winkler
2023-04-03 23:44 ` Emanuel Berg
2023-04-04 2:56 ` Richard Stallman
2023-04-05 7:24 ` Emanuel Berg
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