From: Stefan Monnier via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>
To: help-gnu-emacs@gnu.org
Subject: Re: Is there a way of setting a variable only when it exists?
Date: Mon, 14 Mar 2022 09:16:30 -0400 [thread overview]
Message-ID: <jwvzglssmmq.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: 87lexdul8e.fsf@mbork.pl
> I assume it would be fairly easy to code such a macro (using `boundp'),
> but maybe it exists already?
AFAIK it doesn't exist yet. The reason for it is that it is not
often useful. Typically there are two cases:
- If the var exist, you want to set it and if not you have no fallback.
In that case, it is typically harmless to set the var even when it
doesn't exist, so the code just uses `setq` without bothering to test
`boundp`.
- If the var exist you want to set it, and if it doesn't you want to do
something else. In that case, the something else tends to depend on
the specifics so (if (boundp 'foo) (setq foo ..) ...) is about s good
as it gets.
-- Stefan
next prev parent reply other threads:[~2022-03-14 13:16 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-14 6:00 Is there a way of setting a variable only when it exists? Marcin Borkowski
2022-03-14 12:52 ` Eli Zaretskii
2022-03-14 13:16 ` Stefan Monnier via Users list for the GNU Emacs text editor [this message]
2022-03-14 13:48 ` Emanuel Berg via Users list for the GNU Emacs text editor
2022-03-15 6:17 ` Marcin Borkowski
2022-03-15 6:50 ` Emanuel Berg via Users list for the GNU Emacs text editor
2022-03-15 6:58 ` Jean Louis
2022-03-15 7:45 ` Marcin Borkowski
2022-03-15 8:12 ` Jean Louis
2022-03-15 7:49 ` tomas
2022-03-15 8:13 ` Jean Louis
2022-03-15 8:36 ` tomas
2022-03-15 9:28 ` Jean Louis
2022-03-15 10:01 ` tomas
2022-03-15 11:29 ` Emanuel Berg via Users list for the GNU Emacs text editor
2022-03-15 8:14 ` Emanuel Berg via Users list for the GNU Emacs text editor
2022-03-15 15:33 ` [External] : " Drew Adams
2022-03-15 15:38 ` Drew Adams
2022-03-16 18:32 ` Marcin Borkowski
2022-03-16 0:47 ` Michael Heerdegen
2022-03-16 18:33 ` Marcin Borkowski
2022-03-16 6:02 ` Tomas Nordin
2022-03-16 6:37 ` Emanuel Berg via Users list for the GNU Emacs text editor
2022-03-16 18:34 ` Marcin Borkowski
2022-03-15 6:48 ` Jean Louis
2022-03-14 22:09 ` Michael Heerdegen
2022-03-15 6:16 ` Marcin Borkowski
2022-03-15 7:05 ` Emanuel Berg via Users list for the GNU Emacs text editor
2022-03-16 0:25 ` Michael Heerdegen
2022-03-16 18:33 ` Marcin Borkowski
2022-03-16 19:25 ` Michael Heerdegen
2022-03-18 5:58 ` Marcin Borkowski
2022-03-16 20:35 ` Emanuel Berg via Users list for the GNU Emacs text editor
2022-03-17 20:47 ` Stefan Monnier via Users list for the GNU Emacs text editor
2022-03-18 5:59 ` Marcin Borkowski
2022-03-18 17:59 ` Jean Louis
2022-03-19 9:25 ` Emanuel Berg via Users list for the GNU Emacs text editor
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