GNU bug report logs - #58812
[PATCH] Add '--symlink' to 'guix shell'

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From: zimoun <zimon.toutoune <at> gmail.com>
To: Ludovic Courtès <ludo <at> gnu.org>, Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
Cc: 59164 <at> debbugs.gnu.org, 58812 <at> debbugs.gnu.org
Subject: [bug#58812] [bug#59164] Coding style: similarly-named variables
Date: Thu, 17 Nov 2022 19:44:18 +0100

Hi,

On Thu, 17 Nov 2022 at 18:37, Ludovic Courtès <ludo <at> gnu.org> wrote:

>> It's a pattern I've used at other places; I find it more hygienic to not
>> shadow existing variables; it signal to the reader "be careful, this is
>> not the same as the argument-bound one, though they are closely
>> related".
>
> I don’t buy it.  :-)  The reader might be careful yet end up using the
> “wrong” variable.  As long as the “wrong” variable has no use, I think
> it’s best to shadow it so that mistakes cannot happen.
>
> Of course the details vary depending on context, but I think we should
> not start introducing this pattern in different places.  Perhaps
> something to discuss and codify under “Formatting Code”?

I agree with Ludo.  For another instance than target*, the previous was,

--8<---------------cut here---------------start------------->8---
           ((new '-> old)
[...]
-                 (symlink old (string-append target new)))
[...]
-                       (delete-file (string-append target new))
--8<---------------cut here---------------end--------------->8---

then replaced by,

--8<---------------cut here---------------start------------->8---
           ((new '-> old)
[...]
+           (let ((new* (string-append target* new)))
[...]
+                         (error (format #f "symlink `~a' points to nonexistent \
+file `~a'" new* old)))))
+                   (symlink old new*))
--8<---------------cut here---------------end--------------->8---

Well, it seems a Star War. ;-)  As Ludo, I am not convinced that it is
less error-prone, maybe the contrary.


Cheers,
simon

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