From: Joost Kremers <joostkremers@fastmail.fm>
To: steve-humphreys@gmx.com
Cc: help-gnu-emacs@gnu.org
Subject: Re: Understanding the "let" construct and the setting of variables
Date: Thu, 17 Dec 2020 08:58:39 +0100 [thread overview]
Message-ID: <87tusk2754.fsf@fastmail.fm> (raw)
In-Reply-To: <trinity-663c1ba6-dd2a-4fc2-9468-af0e55f39d72-1608173359580@3c-app-mailcom-bs11>
On Thu, Dec 17 2020, steve-humphreys@gmx.com wrote:
> I ran the following
>
> ELISP> tima
> (lett 845 80)
> "tim_out: 1005"
>
> ELISP> tim
> *** Eval error *** Symbol’s value as variable is void: tim
>
> ELISP> (lett 845 90)
> "tim_out: 1015"
>
> ELISP> tim
> *** Eval error *** Symbol’s value as variable is void: tim
>
> So this is quite different from using "setq". The variable "tim" is
> not available to all of emacs.
Yes, indeed. Variables bound with `let` or `let*` only exist inside the `let`.
So as soon as you put the closing parenthesis matching the opening parenthesis
directly before the `let`, the variables go out of scope and no longer exist.
(There are actually a couple of subtleties involved that make this statement
less than universally true, but those issues shouldn't concern a beginner.)
--
Joost Kremers
Life has its moments
next prev parent reply other threads:[~2020-12-17 7:58 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-17 0:10 Understanding the "let" construct and the setting of variables steve-humphreys
2020-12-17 0:21 ` Joost Kremers
2020-12-17 2:08 ` steve-humphreys
2020-12-17 3:12 ` steve-humphreys
2020-12-17 8:01 ` Joost Kremers
2020-12-17 8:31 ` steve-humphreys
2020-12-17 8:50 ` Joost Kremers
2020-12-17 8:10 ` Joost Kremers
2020-12-17 8:43 ` steve-humphreys
2020-12-17 8:56 ` Joost Kremers
2020-12-18 20:48 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-18 20:46 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-18 21:07 ` Jean Louis
2020-12-18 22:31 ` tomas
2020-12-18 20:39 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-17 2:49 ` steve-humphreys
2020-12-17 7:58 ` Joost Kremers [this message]
2020-12-17 16:55 ` Drew Adams
2020-12-17 20:11 ` steve-humphreys
2020-12-17 21:57 ` Drew Adams
2020-12-17 22:35 ` Michael Heerdegen
2020-12-18 9:01 ` tomas
2020-12-18 9:16 ` Michael Heerdegen
2020-12-18 20:55 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-19 2:17 ` Michael Heerdegen
2020-12-19 2:52 ` Drew Adams
2020-12-19 5:15 ` Stefan Monnier
2020-12-18 20:33 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-17 0:25 ` steve-humphreys
2020-12-17 0:35 ` steve-humphreys
2020-12-17 1:05 ` Joost Kremers
2020-12-17 1:20 ` steve-humphreys
2020-12-18 20:58 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-17 4:34 ` Jean Louis
2020-12-17 5:12 ` steve-humphreys
2020-12-19 6:06 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-17 7:31 ` steve-humphreys
2020-12-19 5:55 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-19 6:49 ` Jean Louis
2020-12-20 5:19 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-18 17:14 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-18 17:48 ` tomas
2020-12-18 15:33 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-18 18:12 ` Jean Louis
2020-12-18 18:20 ` Drew Adams
2020-12-18 18:45 ` Jean Louis
2020-12-18 19:16 ` Drew Adams
2020-12-18 20:00 ` Jean Louis
2020-12-18 21:27 ` Christopher Dimech
2020-12-19 6:23 ` Emanuel Berg via Users list for the GNU Emacs text editor
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