[bug#58339] [PATCH 2/2] gnu: Add guix-example.

[Liliana Marie Prikler <liliana.prikler@gmail.com>]

Am Donnerstag, dem 06.10.2022 um 18:39 +0200 schrieb zimoun:
> * gnu/packages/guix-extensions.scm (guix-example): New variable.
> ---
>  gnu/packages/guix-extensions.scm | 39
> +++++++++++++++++++++++++++++++-
>  1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/gnu/packages/guix-extensions.scm b/gnu/packages/guix-
> extensions.scm
> index 6294c15f3d..6541630ddd 100644
> --- a/gnu/packages/guix-extensions.scm
> +++ b/gnu/packages/guix-extensions.scm
> @@ -19,7 +19,44 @@ (define-module (gnu packages guix-extensions)
>    #:use-module (guix gexp)
>    #:use-module (guix packages)
>    #:use-module (guix build-system trivial)
> -  #:use-module (gnu packages base))
> +  #:use-module (guix build-system guile)
> +  #:use-module (guix git-download)
> +  #:use-module (gnu packages base)
> +  #:use-module (gnu packages package-management))
> +
> +(define-public guix-example
> +  (let ((commit "d600bd742dae9df86e980a25cf1d0ac71ee01438")
> +        (revision "0"))
> +    (package
> +      (name "guix-example")
> +      (version (git-version "0" revision commit))
> +      (source
> +       (origin
> +         (method git-fetch)
> +         (uri (git-reference
> +               (url "https://gitlab.com/zimoun/guix-example")
> +               (commit commit)))
> +         (file-name (string-append name version "-checkout"))
> +         (sha256
> +          (base32
> +          
> "0s48b5a1i0vkx5lq7jn9b46zzqv2g3dli7b54sd9365dszqjqzmx"))))
> +      (build-system guile-build-system)
> +      (arguments
> +       '(#:phases (modify-phases %standard-phases
> +                    (add-after 'install 'move-to-extension-directory
> +                      (lambda* (#:key outputs #:allow-other-keys)
> +                        (let* ((out (assoc-ref outputs "out"))
> +                               (target (string-append
> +                                        out
> +                                       
> "/share/guix/extensions/example.scm")))
> +                          (mkdir-p (dirname target))
> +                          (rename-file (car (find-files out
> "example.scm"))
> +                                       target)))))))
> +      (native-inputs (list (lookup-package-input guix "guile")
> guix))
> +      (home-page "") ; Should be documentation location for
> GUIX_EXTENSIONS_PATH
Note that this example has a home-page.
> +      (synopsis "Example of Guix sub-command extension")
> +      (description "This Guix extension provides a simple example to
> extend Guix subcommands.")
> +      (license license:gpl3+))))
While Ludo said "Maybe we should just keep it as an example in the
source tree?", I'm really not sure whether that's the best course of
action.  It will simultaneously act as a package that users won't know
how to use (as evidenced by some people now and then asking how to run
gwl) *and* as not that great of an example on how to write extension,
because people only have the history of the Guix repo to go by.

For a proper guide, I think we should walk through:

1. Writing a sample extension (e.g. one simply printing hello world)
2. Testing the extension via `guix shell'
3. (Pointers on) submitting the extension to Guix proper or managing it
in one's own channel

For now, we barely cover 1.

Cheers