Re: more package transformations: overrides

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

Hello,

Ricardo Wurmus <rekado@elephly.net> writes:

> Maxim Cournoyer <maxim.cournoyer@gmail.com> writes:
>
>>> I think it would improve usability to be able to use the *same* names in
>>> an override file.  Got a package with name “python-pytorch” in that
>>> file?  It replaces “python-pytorch” in the graph.
>>
>> It's still a bit too abstract in my mind.  Could you please provide a
>> skeletton of what the overrides file would look like?
>
> It would just like a file you’d pass to “guix build -f”, except that it
> wouldn’t need to evaluate to a single package.  It would contain a bunch
> of package definitions.
>
> This would replace the need to set GUIX_PACKAGE_PATH (or pass -L) to a
> directory containing a module, and set up package transformations for
> each package.
>
> It would also be lighter than requiring the use of a manifest, which can
> get rather complicated when more than a few packages are to be replaced
> in the graph.

I see.  I can see how that could be convenient, but I'm a bit wary of
introducing yet another way to rewrite inputs (we have the CLI and the
manifest already).  On the other hand, the stdin/--args-file trick could
be universally useful and be a way to leverage the CLI in a more
user/vcs-friendly way (the CLI should be easier to approach than writing
a package definition -- if it's not let's discuss how to improve it), so
perhaps we could start with implementing that?

-- 
Thanks,
Maxim