[bug#62056] [PATCH] guix: Only issue erase-current-line sequence for ttys.

[Ludovic Courtès]

Hi,

Bruno Victal <mirai@makinata.eu> skribis:

> * guix/progress.scm (erase-current-line): Only issue erase-current-line 
> sequence for ttys.
> ---
>
> Avoids cluttering log lines with �[K when output is logged to a file.

+1!

>  (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).

Could you see which use of ‘erase-current-line’ is causing problems?

TIA,
Ludo’.