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Re: Appending to a list
From: |
steve-humphreys |
Subject: |
Re: Appending to a list |
Date: |
Sun, 13 Dec 2020 22:46:09 +0100 |
> Sent: Sunday, December 13, 2020 at 10:30 PM
> From: "Óscar Fuentes" <ofv@wanadoo.es>
> To: help-gnu-emacs@gnu.org
> Subject: Re: Appending to a list
>
> 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") ))
Can one just append lists together, then store the result to one of the
variables, as I did?
Or could such an approach lead to unintended consequences in some circumstances?
Regards
Steve
> > 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)
>
> ?
>
>
>
- Appending to a list, steve-humphreys, 2020/12/13
- Re: Appending to a list, Joost Kremers, 2020/12/13
- Re: Appending to a list, Óscar Fuentes, 2020/12/13
- Re: Appending to a list,
steve-humphreys <=
- Re: Appending to a list, Stefan Monnier, 2020/12/13
- Re: Appending to a list, steve-humphreys, 2020/12/13
- Re: Appending to a list, Emanuel Berg, 2020/12/13
- Re: Appending to a list, steve-humphreys, 2020/12/13
- Re: Appending to a list, Emanuel Berg, 2020/12/13
- Re: Appending to a list, steve-humphreys, 2020/12/13
- Re: Appending to a list, Emanuel Berg, 2020/12/13
- Re: Appending to a list, steve-humphreys, 2020/12/13
- Re: Appending to a list, Michael Heerdegen, 2020/12/13
- Re: Appending to a list, Emanuel Berg, 2020/12/13