Subject: [bug#56803] [PATCH 0/6] Add hydrus network and its dependencies

From: "(" <[email-masked]>
Date: Sat, 13 Aug 2022 22:26:24 +0100

Hey,

On Sat Aug 13, 2022 at 3:34 PM BST, Tomasz Jeneralczyk wrote:
> > In addition, this substitution should be done in a phase rather than in
> > a snippet, because (1) the result of ‘guix build -S’ should be
> > platform-independent and thus not include the file name of ‘mpv’ for a
> > particular system, and (2) the reference to variable ‘mpv’ at the top
> > level can cause problems due to circular dependencies among modules.
> And if I understand the 2nd point correctly I should use something like 
> `(assoc-ref inputs "mpv")` instead of `#$mpv`, right? I  cannot use 
> `(search-input-file ...)` because the name of the mpv's lib is 
> determined during runtime by the python code and I didn't want to 
> hardcode the mpv so file's version.

No, the assoc-ref style is basically deprecated last I heard. The problem
is with snippets: apparently something with the definition of the `snippet`
field can cause module dependency issues, whereas `arguments` does not
suffer from the same. IIRC, the issue is that the former is not specifie
as a `(delayed)` field. So, #$pkg is okay in arguments, but sometimes not
in snippets.

    -- (