From: Jean Abou Samra <jean@abou-samra.fr>
To: Heime <heimeborgia@protonmail.com>,
Heime via Users list for the GNU Emacs text editor
<help-gnu-emacs@gnu.org>
Subject: Re: Calling a function with undefined symbol
Date: Mon, 31 Oct 2022 09:32:57 +0100 [thread overview]
Message-ID: <ee399870-fa48-e856-8c39-70b9700e6b70@abou-samra.fr> (raw)
In-Reply-To: <eqqgsiarlPx99ydnZd2qRGKNtGJ62jnOxsnnD5pkIISspm3C-nHURPT8Zv2F7bEkI41R5W6HvP_ufQE9FIP88aZ9AluQzva2hhTpFD9OgDo=@protonmail.com>
Le 31/10/2022 à 09:15, Heime a écrit :
> Have written a function named "mbcomplt" that takes a symbol.
>
> (defun mbcomplt (sgnl)
> "DOC."
>
> (if (eq sgnl 'go)
> (message "go")
> (message "nogo")))
>
> I can call this function with
>
> (mbcomplt 'go)
>
> This even though the symbol "'go" does not exist. What is happening here?
>
> My understanding about symbols is that I can make a symbol using
>
> (defvar seqr 3) ; set symbol seqr with value 3
> (setq seqr 5) ; set symbol seqr with value 5
>
> (symbol-value 'seqr) ; get value of symbol (returns 5)
> (symbol-name 'seqr) ; get name of symbol (returns "seqr")
It may be helpful to view symbols as some kind of modified
strings. The symbol 'go is an amorphous object, just a name
for something. You can use it as a name, or as a discrete
key, or whatever. You can also "define" it, or rather
define a variable with its name, and then you are able
to use symbol-value on it, but the symbol object itself is
a *potential* name and does not need to have a variable with
its name defined in order to be used.
Jean
next prev parent reply other threads:[~2022-10-31 8:32 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-31 8:15 Calling a function with undefined symbol Heime
2022-10-31 8:32 ` Jean Abou Samra [this message]
2022-10-31 8:42 ` tomas
2022-10-31 8:57 ` Heime
2022-10-31 9:07 ` tomas
2022-10-31 9:24 ` Jean Abou Samra
2022-10-31 9:43 ` Heime
2022-10-31 9:58 ` Jean Abou Samra
2022-10-31 10:57 ` Heime
2022-10-31 17:00 ` [External] : " Drew Adams
2022-10-31 17:10 ` Emanuel Berg
2022-11-01 4:11 ` Drew Adams
2022-11-01 5:24 ` tomas
2022-11-01 15:58 ` Drew Adams
2022-11-01 16:13 ` tomas
2022-11-01 19:22 ` Drew Adams
2022-10-31 12:29 ` Stefan Monnier via Users list for the GNU Emacs text editor
2022-10-31 15:37 ` Emanuel Berg
2022-11-02 12:14 ` Michael Heerdegen
2022-11-02 14:25 ` Sam Steingold
2022-11-02 16:40 ` Michael Heerdegen
2022-11-02 17:28 ` Emanuel Berg
2022-11-02 23:04 ` Emanuel Berg
2022-11-03 11:09 ` Michael Heerdegen
2022-11-03 12:15 ` Emanuel Berg
2022-11-04 12:16 ` Michael Heerdegen
2022-11-05 14:32 ` Emanuel Berg
2022-11-05 23:22 ` Michael Heerdegen
2022-11-06 20:17 ` Emanuel Berg
2022-11-07 16:03 ` Michael Heerdegen
2022-11-07 16:50 ` [External] : " Drew Adams
2022-11-07 16:52 ` Emanuel Berg
2022-11-08 15:52 ` Michael Heerdegen
2022-11-08 19:15 ` tomas
2022-11-08 19:57 ` Michael Heerdegen
2022-11-08 20:47 ` tomas
2022-11-08 21:35 ` Sam Steingold
2022-11-08 23:53 ` Michael Heerdegen
2022-11-09 15:32 ` Sam Steingold
2022-11-09 15:59 ` Michael Heerdegen
2022-11-16 19:07 ` Emanuel Berg
2022-11-16 21:40 ` [External] : " Drew Adams
2022-11-16 21:55 ` Emanuel Berg
2022-11-04 14:33 ` Michael Heerdegen
2022-11-05 12:57 ` Emanuel Berg
2022-10-31 11:34 ` Emanuel Berg
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