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[bug#62056] [PATCH] guix: Only issue erase-current-line sequence for tty
From: |
Ludovic Courtès |
Subject: |
[bug#62056] [PATCH] guix: Only issue erase-current-line sequence for ttys. |
Date: |
Tue, 18 Apr 2023 22:02:00 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) |
Hi Bruno,
Bruno Victal <mirai@makinata.eu> skribis:
> On 2023-03-16 21:30, Ludovic Courtès wrote:
>> Bruno Victal <mirai@makinata.eu> skribis:
>>> (define (erase-current-line port)
>>> - "Write an ANSI erase-current-line sequence to PORT to erase the whole
>>> line and
>>> -move the cursor to the beginning of the line."
>>> - (display "\r\x1b[K" port))
>>> + "When @var{port} is interactive, write an ANSI erase-current-line
>>> sequence
>>> +to erase the whole line and move the cursor to the beginning of the line,
>>> +otherwise write a newline."
>>> + (if (isatty? port)
>>> + (display "\r\x1b[K" port)
>>> + (newline port)))
>>
>> We should avoid calling ‘isatty?’ every time, it’s too costly, which is
>> why there’s also ‘isatty?*’ somewhere that memoizes things.
>>
>> However, it seems up to the caller to check that before calling
>> ‘erase-current-line’. That seems to be the case within progress.scm and
>> in (guix status).
>
> guix/status.scm:471 defines a erase-current-line* which calls isatty?*.
> Does this mean that erase-current-line has to be “wrapped” every time
> we want it to have tty awareness?
‘erase-current-line’ is low-level and often the caller has already done
an ‘isatty?’ check before calling it (for instance in progress bars). I
think that’s the reason it doesn’t include that check.
> If that's not the case, perhaps we could change the signature of
> erase-current-line to:
> (define* (erase-current-line port #:optional tty?)
I don’t think so.
>> Could you see which use of ‘erase-current-line’ is causing problems?
>
> guix/scripts/substitute.scm:318
In this particular case, how about returning a different
<progress-reporter> depending on ‘isatty?’?
Thanks,
Ludo’.
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