A capture-stdout wrapper procedure in (guix build utils)?

A capture-stdout wrapper procedure in (guix build utils)?

[Fabio Natali]

Hallo,

I noticed this capture-stdout wrapper procedure while reviewing Tomas'
patch 68289⁰:

,----
| (define (capture-stdout . prog+args)
|   (let* ((port (apply open-pipe* OPEN_READ prog+args))
|          (data (get-string-all port)))
|     (if (= 0 (status:exit-val (close-pipe port)))
|         (string-trim-right data #\newline)
|         (error "command failed"))))
`----

Since this seems to be a somewhat general and useful pattern, do you
think it might be worth to add it (or a variation thereof) to '(guix
build utils)'?

Thanks, best wishes, Fabio.


⁰ https://issues.guix.gnu.org/issue/68289/#0-lineno93


-- 
Fabio Natali
https://fabionatali.com

Re: A capture-stdout wrapper procedure in (guix build utils)?

[Felix Lechner via Development of GNU Guix and the GNU System distribution.]

Hi Fabio,

On Sat, Apr 20 2024, Fabio Natali wrote:

> do you think it might be worth to add it (or a variation thereof) to
> '(guix build utils)'?

I use this [1] which gives the caller access to the exit status and is
also slightly shorter:

    (define (command-with-output-to-string/status* command)
      (let* ((input-pipe (apply open-pipe* OPEN_READ command))
    	 (output (get-string-all input-pipe))
    	 (exit-val (status:exit-val (close-pipe input-pipe))))
        (values output exit-val)))

It may be better, however, to finally fix Guile's 'system' and 'system*'
to work with 'with-output-to-string'. [2]

Kind regards
Felix

[1] https://codeberg.org/lechner/preambled-exec/src/commit/c5c498c3890f22cda070fe35b314f01982ebc885/test/simple-variable.scm#L28-L32
[2] https://debbugs.gnu.org/cgi/bugreport.cgi?bug=43364

Re: A capture-stdout wrapper procedure in (guix build utils)?

[Fabio Natali]

On 2024-04-21, 08:35 -0700, Felix Lechner <felix.lechner@lease-up.com> wrote:
> It may be better, however, to finally fix Guile's 'system' and
> 'system*' to work with 'with-output-to-string'. [2]

Hi Felix,

Thanks for getting back to me.

Great point re potentially fixing this further up in the "chain",
i.e. in Guile. I'll try and raise this on the Guile IRC channel and/or
ML and update this thread with my findings.

Thanks, best wishes, Fabio.


-- 
Fabio Natali
https://fabionatali.com