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[bug#53676] [PATCH 4/5] services: pulseaudio: Add an extra-script-files
From: |
Liliana Marie Prikler |
Subject: |
[bug#53676] [PATCH 4/5] services: pulseaudio: Add an extra-script-files configuration field. |
Date: |
Sun, 06 Feb 2022 09:02:22 +0100 |
User-agent: |
Evolution 3.42.1 |
Hi Maxim,
Am Sonntag, dem 06.02.2022 um 02:25 -0500 schrieb Maxim Cournoyer:
> Hi Liliana,
>
> [...]
>
> > > 'strip-store-file-name' would be able to get the name from the
> > > store
> > > item (built derivation), but file-union takes a "two-element list
> > > where the first element is the file name to use in the new
> > > directory,
> > > and the second element is a gexp denoting the target file", e.g.,
> > > before the file-like object is built. I don't see an easy way to
> > > make it work.
> > For the record, I do think we'd like to use file-like objects here,
> > not
> > raw gexps. If that fails, why not expose the name to gexp mapping
> > completely? I don't know why you'd want to take away that control.
>
> If we limit ourselves to file-like objects, we can do something like
> this:
>
> --8<---------------cut here---------------start------------->8---
> 1 file changed, 20 insertions(+), 4 deletions(-)
> gnu/services/sound.scm | 24 ++++++++++++++++++++----
>
> modified gnu/services/sound.scm
> @@ -26,10 +26,12 @@ (define-module (gnu services sound)
> #:use-module (gnu services)
> #:use-module (gnu system pam)
> #:use-module (gnu system shadow)
> + #:use-module (guix diagnostics)
> #:use-module (guix gexp)
> #:use-module (guix packages)
> #:use-module (guix records)
> #:use-module (guix store)
> + #:use-module (guix ui)
> #:use-module (gnu packages audio)
> #:use-module (gnu packages linux)
> #:use-module (gnu packages pulseaudio)
> @@ -149,10 +151,24 @@ (define pulseaudio-environment
> ("PULSE_CLIENTCONFIG" . "/etc/pulse/client.conf")))))
>
> (define (extra-script-files->file-union extra-script-files)
> - "Return a G-exp obtained by processing EXTRA-SCRIPT-FILES with FILE-
> UNION.
> -Each file is named \"snippet-n.pa\", where N is their 1-offset index."
> - (let ((labels (map (lambda (n) (format #f "snippet-~a.pa" n))
> - (iota (length extra-script-files) 1))))
> + "Return a G-exp obtained by processing EXTRA-SCRIPT-FILES with FILE-
> UNION."
> +
> + (define (file-like->name file)
> + (let ((name (match file
> + ((? local-file?)
> + (local-file-name file))
> + ((? plain-file?)
> + (plain-file-name file))
> + ((? computed-file?)
> + (computed-file-name file))
> + (_ (leave (G_ "~a is not a local-file, plain-file or
> \
> +computed-file object~%") file)))))
> + (unless (string-suffix? name ".pa")
> + (leave (G_ "`~a' lacks the required '.pa' file name
> extension~%")
> + name))
> + name))
> +
> + (let ((labels (map file-like->name extra-script-files)))
> (file-union "default.pa.d" (zip labels extra-script-files))))
>
> (define pulseaudio-etc
> --8<---------------cut here---------------end--------------->8---
>
> It works; and I agree it's nice to have control over the file name.
Note that file-like->name serves multiple duties here. In my opinion
it'd be better to
--8<---------------cut here---------------start------------->8---
(define (file-like-name file)
((match file
((? local-file?) local-file-name)
((? plain-file?) plain-file-name)
((? computed-file?) computed-file-name)
[...]
(_ (const #f))) ; alternatively raise an error
file))
--8<---------------cut here---------------end--------------->8---
That at least decouples it from the burden of having to check whether
it is a valid pulseaudio script file name, which makes it reusable
elsewhere. As a note regarding correctness, perhaps we should write an
implementation in (guix gexp) that works for everything that has a
gexp-compiler, but that's out of scope for now.
On the pulseaudio side, you'd compose that with an
--8<---------------cut here---------------start------------->8---
(define (assert-pulseaudio-script-file-name name)
(unless name (raise ...))
(unless (string-suffix? name ".pa") (leave ...))
name)
--8<---------------cut here---------------end--------------->8---
Cheers