unofficial mirror of help-gnu-emacs@gnu.org
 help / color / mirror / Atom feed
From: Corwin Brust <corwin@bru.st>
To: goncholden <goncholden@protonmail.com>
Cc: Help Gnu Emacs mailing list <help-gnu-emacs@gnu.org>,
	Emanuel Berg <moasenwood@zoho.eu>
Subject: Re: Function passing flag
Date: Tue, 8 Mar 2022 14:09:51 -0600	[thread overview]
Message-ID: <CAJf-WoS68on6yMAu6T=VYpUGr+p8OWeiqmm9bh5D7N6TGujr4Q@mail.gmail.com> (raw)
In-Reply-To: <cG5j3Em1l4bfCsiS1b-Aa7Gg_T8L8sRkIkNtVwqxCUuaJop4SL3MLCOhQf8ArKDMyqoHMof-_UobMnwhuMyrC7i5YjNanXJ2e1lVzVU7FMg=@protonmail.com>

On Tue, Mar 8, 2022 at 1:36 PM goncholden <goncholden@protonmail.com> wrote:
>
> How does one do it with an optional argument?  Where can I read about this?
>

A function with an optional argument ARG might look like this:

(defun my:own-fun (&optional arg)
  "Do something. When ARG is non-nil do it a lot."
  (if arg
      ;; when ARG is true we run this
      (do-stuff)
    ;; else we run this
    (do-more-or-different-stuff)))

Note, if you are defining a command (a function you will bind to a key
or otherwise use interactively), you will want to to use
(interactive), usually placed at the start of the function definition,
so just after the docstring.



  reply	other threads:[~2022-03-08 20:09 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-08 12:24 Function passing flag goncholden via Users list for the GNU Emacs text editor
2022-03-08 18:00 ` Emanuel Berg via Users list for the GNU Emacs text editor
2022-03-08 19:00   ` goncholden
2022-03-08 19:14     ` Emanuel Berg via Users list for the GNU Emacs text editor
2022-03-08 19:35       ` goncholden
2022-03-08 20:09         ` Corwin Brust [this message]
2022-03-08 20:15           ` Corwin Brust
2022-03-08 20:28           ` goncholden
2022-03-08 20:42             ` Corwin Brust
2022-03-08 20:55               ` goncholden

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://www.gnu.org/software/emacs/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAJf-WoS68on6yMAu6T=VYpUGr+p8OWeiqmm9bh5D7N6TGujr4Q@mail.gmail.com' \
    --to=corwin@bru.st \
    --cc=goncholden@protonmail.com \
    --cc=help-gnu-emacs@gnu.org \
    --cc=moasenwood@zoho.eu \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).