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Re: [External] : Re: Appending lists
From: |
Jean Louis |
Subject: |
Re: [External] : Re: Appending lists |
Date: |
Sun, 20 Jun 2021 22:59:10 +0300 |
User-agent: |
Mutt/2.0.7+183 (3d24855) (2021-05-28) |
* Emanuel Berg via Users list for the GNU Emacs text editor
<help-gnu-emacs@gnu.org> [2021-06-20 22:51]:
> After this discussion, I thought I'd examine my `nconc' once
> more and I then realized my use of them resembles a functional
> style, while it (nconc) is already destructively doing the
> updating, so that's not needed. E.g., this
>
> ;; (setq completion-ignored-extensions
> ;; (nconc completion-ignored-extensions '(".bcf" ".elc" ".run.xml")) )
>
> can be changed into (should be changed, since the above makes
> no difference - ?) it can be changed into
>
> (nconc completion-ignored-extensions '(".bcf" ".run.xml"))
I would use it this way:
(setq completion-ignored-extensions
(append completion-ignored-extensions '(".bcf" ".run.xml")))
As that follows the habit and logic I am personally used to. It is
style preference. I like that previous variables stay the same:
(setq list-a '(1 2 3)) ⇒ (1 2 3)
(setq list-b '(a b c)) ⇒ (a b c)
(append list-a list-b) ⇒ (1 2 3 a b c)
list-a ⇒ (1 2 3)
list-b ⇒ (a b c)
But then I can use the previously defined variables to define a new
one:
(setq appended (append list-a list-b)) ⇒ (1 2 3 a b c)
and nothing changed in those:
list-a ⇒ (1 2 3)
list-b ⇒ (a b c)
while using function `nconc' would give me a habit that I rather find
detrimental or not pleasing:
(nconc appended list-a list-b) ⇒ (1 2 3 a b c 1 2 3 a b c . #6)
list-a ⇒ (1 2 3 a b c 1 2 3 a b c . #6)
list-b ⇒ (a b c 1 2 3 a b c 1 2 3 . #6)
Question is why do I need to change other lists if all what I want is
to set the first variable `appended' to someting new?
So if I don't need to change other variables I will not use `nconc'
and rather use function `append'
--
Jean
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- Re: Appending lists, (continued)
- Re: Appending lists, tomas, 2021/06/17
- Re: Appending lists, Emanuel Berg, 2021/06/18
- Re: Appending lists, Emanuel Berg, 2021/06/18
- Re: Appending lists, tomas, 2021/06/19
- Re: Appending lists, Emanuel Berg, 2021/06/19
- RE: [External] : Re: Appending lists, Drew Adams, 2021/06/19
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20
- Re: [External] : Re: Appending lists, Jean Louis, 2021/06/20
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20
- Re: [External] : Re: Appending lists,
Jean Louis <=
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20
- Re: [External] : Re: Appending lists, Jean Louis, 2021/06/20
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20
- Re: [External] : Re: Appending lists, Jean Louis, 2021/06/20
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20
- Re: [External] : Re: Appending lists, Jean Louis, 2021/06/20
- Re: [External] : Re: Appending lists, Stefan Monnier, 2021/06/20
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20