Re: rolling back only a single package

[cdelia]

Hi Ricardo,

thanks for answering,

so basically this is equivalent to find the generation of commit
65956a... and invoking guix-generation-x to install guile-json.

Yes, I see why this it's better than using "guix package -i *" and it
relates well to my other question about profile -> packages definitions
generation.

Just write manifests, instantiate them and when it's time to migrate the
pacakges definitions will already there.

What happens if you then do "guix package -i guile-json" or if somewhere
in the future "guix package -U" after a pull?

It will honor the manifest or just install the guile-json on the package
definition?

I don't know if I can make my mind on what sort of behaviur should be
best but maybe I'm more towards the idea that a manifest should take
precedence, maybe with an override flag.

Anyway I can try and check later what guix does.

Thanks! and have a happy new year eve.

Ricardo Wurmus <address@hidden> writes:
> Inferiors work, but you’d use them in manifests.  The idea is to install
> the package with an old version of Guix, but to do it in code instead of
> manually.  Here’s an example:
>
> (use-modules (guix inferior) (guix channels)
>              (srfi srfi-1))   ;for 'first'
>
> (define channels
>   ;; This is the old revision from which we want to
>   ;; extract guile-json.
>   (list (channel
>          (name 'guix)
>          (url "https://git.savannah.gnu.org/git/guix.git";)
>          (commit
>           "65956ad3526ba09e1f7a40722c96c6ef7c0936fe"))))
>
> (define inferior
>   ;; An inferior representing the above revision.
>   (inferior-for-channels channels))
>
> ;; Now create a manifest with the current "guile" package
> ;; and the old "guile-json" package.
> (packages->manifest
>  (list (first (lookup-inferior-packages inferior "guile-json"))
>        (specification->package "guile")))
>
> You can instantiate the manifest the usual way:
>
>     guix package -m /path/to/manifest.scm
>
> --
> Ricardo

--
Catriel