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Re: Appending lists
From: |
Philip Kaludercic |
Subject: |
Re: Appending lists |
Date: |
Wed, 16 Jun 2021 21:24:19 +0000 |
<tomas@tuxteam.de> writes:
> On Wed, Jun 16, 2021 at 08:36:00PM +0300, Jean Louis wrote:
>> * Philip Kaludercic <philipk@posteo.net> [2021-06-16 16:07]:
>> > > (setq list '(A B C)) ⇒ (A B C)
>> > > (nconc list '(1 2 3)) ⇒ (A B C 1 2 3)
>> > > list ⇒ (A B C 1 2 3)
>> >
>> > Change that to
>> >
>> (let* ((list-1 '(a b c))
>> (list-2 (nconc list-1 '(1 2 3))))
> ^^^^ not recommended: '(a b c) is a "constant object"
> Some version of elisp might even refuse to do that!
True, I wanted to do (list 'a 'b 'c) but I didn't want to change the
example that much.
Also, what versions of elisp wouldn't allow that?
>> (eq list-1 list-2)) ;; => t
>>
>> eq - Return t if the two args are the same Lisp object.
>>
>> And we talked how variable's value does not change... values or Lisp
>> objects?
>>
>> (setq list-1 '(a b c))
>> list-1 ⇒ (a b c)
>> (setq list-2 (nconc list-1 '(1 2 3))) ⇒ (a b c 1 2 3)
>> list-2 ⇒ (a b c 1 2 3)
>> (eq list-1 list-2) ⇒ t
>> list-1 ⇒ (a b c 1 2 3)
>>
>> How I see that is that it is same lisp object, but I can visually see
>> that the value changed.
>>
>> Maybe Thomas wanted to say that lisp object does not change?
>
> On the contrary. Mutable objects can change. Cons cells are
> mutable objects, and thus lists, which are made of those.
>
> Cheers
> - t
>
--
Philip K.
- Re: Appending lists, (continued)
- Re: Appending lists, Yuri Khan, 2021/06/16
- Re: Appending lists, Jean Louis, 2021/06/16
- Re: Appending lists, tomas, 2021/06/16
- Re: Appending lists, Jean Louis, 2021/06/16
- Re: Appending lists, Emanuel Berg, 2021/06/16
- Re: Appending lists, Jean Louis, 2021/06/16
- Re: Appending lists, Philip Kaludercic, 2021/06/16
- Re: Appending lists, Emanuel Berg, 2021/06/16
- Re: Appending lists, Jean Louis, 2021/06/16
- Re: Appending lists, tomas, 2021/06/16
- Re: Appending lists,
Philip Kaludercic <=
- Re: Appending lists, Emanuel Berg, 2021/06/16
- Re: Appending lists, tomas, 2021/06/17
- Re: Appending lists, tomas, 2021/06/17
- Re: Appending lists, Emanuel Berg, 2021/06/16
- Re: Appending lists, Emanuel Berg, 2021/06/16
- [OT] Underground (was: Appending lists), tomas, 2021/06/16
- Re: [OT] Underground (was: Appending lists), Emanuel Berg, 2021/06/18
- Re: Appending lists, Emanuel Berg, 2021/06/16
- Re: Appending lists, tomas, 2021/06/16
- Re: Appending lists, Jean Louis, 2021/06/16