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Re: [External] : Re: Appending lists
From: |
Emanuel Berg |
Subject: |
Re: [External] : Re: Appending lists |
Date: |
Mon, 21 Jun 2021 00:54:58 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
Jean Louis wrote:
>> (setq list-head '(1)) ; (1)
>> (setq list-tail '(2 3 4)) ; (2 3 4)
>> (setq whole-list (append list-head list-tail)) ; (1 2 3 4)
>> (setcdr list-tail '(3.5 4)) ; (3.5 4)
>> whole-list ; (1 2 3.5 4) <-- the tail has changed
>> (setcar list-head 1.5)
>> whole-list ; <-- but here, the head is still unaffected, (1 2 3.5 4)
>> (setcar whole-list 1.33) ; well, of course that will work...
>> whole-list ; (1.33 2 3.5 4)
>> list-head ; still (1.5)
>
> (setq list-head '(1)) ⇒ (1)
> (setq list-tail '(2 3 4)) ⇒ (2 3 4)
> (setq whole-list (append list-head (copy-sequence list-tail))) ⇒ (1 2 3 4)
> (setcdr list-tail '(3.5 4)) ⇒ (3.5 4) ; (3.5 4)
> It did not change now:
> whole-list ⇒ (1 2 3 4) ; (1 2 3.5 4) <-- the tail has changed
But here it did again, despite `copy-sequence'!
(progn
(setq list-head '(1))
(setq list-tail '(2 3 4))
(setq list-tail-2 (copy-sequence list-tail))
(setq whole-list (append list-head list-tail-2))
(setcdr list-tail-2 '(3.5 4))
whole-list
) ; (1 2 3.5 4)
Oh, no!
--
underground experts united
https://dataswamp.org/~incal
- RE: [External] : Re: Appending lists, (continued)
- 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, 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, Emanuel Berg, 2021/06/20
- Re: [External] : Re: Appending lists, Jean Louis, 2021/06/20
- Re: [External] : Re: Appending lists,
Emanuel Berg <=
- 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
- Re: [External] : Re: Appending lists, Emanuel Berg, 2021/06/20