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From: "Óscar Fuentes" <ofv@wanadoo.es>
To: help-gnu-emacs@gnu.org
Subject: Re: Appending to a list
Date: Sun, 13 Dec 2020 22:30:52 +0100	[thread overview]
Message-ID: <87sg89v1f7.fsf@telefonica.net> (raw)
In-Reply-To: 877dpljtwg.fsf@fastmail.fm

Joost Kremers <joostkremers@fastmail.fm> writes:

> On Sun, Dec 13 2020, steve-humphreys@gmx.com wrote:
>> Would appending to list like this be good?
>>
>> (setq bird '("Toucan" "King Fisher"))
>> (setq bird (append bird ("Swift") ))
>
> This should result in an error, because `("Swift")` isn't quoted. You'd need:
>
>     (setq bird (append bird '("Swift")))
>
> But note that the last argument of `append` isn't copied, so it may not be a
> good idea to use a literal list.
>
>> Or does one customarily use other constructs for
>> adding to a list?
>
> `push` is what I would use:
>
>     (push "Swift" bird)

This does not append.

> No need to use `setq` here.
>
> `push` won't check if the element is already in the list, though. You can use
> `cl-pushnew` in that case, but be sure to load the library it's in:
>
>     (require 'cl-lib)
>     (cl-pushnew "Swift" bird)

Isn't that the same as

(add-to-list bird "Swift" t)

?




  reply	other threads:[~2020-12-13 21:30 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-13 20:46 Appending to a list steve-humphreys
2020-12-13 21:03 ` Joost Kremers
2020-12-13 21:30   ` Óscar Fuentes [this message]
2020-12-13 21:46     ` steve-humphreys
2020-12-13 22:37     ` Joost Kremers
2020-12-13 23:08       ` Joost Kremers
2020-12-13 22:43     ` Stefan Monnier
2020-12-13 23:25       ` steve-humphreys
2020-12-13 23:33         ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-14  0:19           ` steve-humphreys
2020-12-14  0:37             ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-14  2:54               ` steve-humphreys
2020-12-14  2:58                 ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-14  3:23                   ` steve-humphreys
2020-12-14  4:07                 ` Michael Heerdegen
2020-12-14  4:16                   ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-14  4:23                   ` steve-humphreys
2020-12-14  4:50                     ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-14  5:13                       ` steve-humphreys
2020-12-14  6:20                         ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-14  6:25                           ` steve-humphreys
2020-12-14  5:28                       ` steve-humphreys
2020-12-14  6:26                         ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-14 10:25                           ` steve-humphreys
2020-12-14  5:55                       ` steve-humphreys
2020-12-14  6:36                         ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-14 17:22                     ` Michael Heerdegen
2020-12-14 18:25                       ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-15  0:17                         ` steve-humphreys
2020-12-15  1:38                           ` Emanuel Berg via Users list for the GNU Emacs text editor
2020-12-13 21:41   ` steve-humphreys
2020-12-13 23:31     ` Emanuel Berg via Users list for the GNU Emacs text editor

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