Re: [External] : Re: Appending lists

[Emanuel Berg via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

Jean Louis wrote:

> (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?

We have been thru this already, the destructive update is what
`nconc' does and one should use it when that's what is
desired...

> So if I don't need to change other variables I will not use
> `nconc' and rather use function `append'

They do different things, and I want both please...

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