Re: [PATCH 1/2] build: Generalize 'package-with-explicit-python'.

[Ricardo Wurmus]

Federico Beffa <address@hidden> writes:

> Generalize the Python procedure to recursively replace compiler/interpreter.
> From a8220b430d196e5bb079e23ac63b1acd16fdaaee Mon Sep 17 00:00:00 2001
> From: Federico Beffa <address@hidden>
> Date: Wed, 8 Feb 2017 18:55:32 +0100
> Subject: [PATCH 1/2] build: Generalize 'package-with-explicit-python'.
>
> * guix/build-system/python.scm (package-with-explicit-python): Remove it and
>   replace it with the generalized procedure 'package-with-explicit-compiler'
>   in the new file. (package-with-python2): Adapt it.
> * guix/build-system/utils.scm: New file with the generalized procedure.
> * Makefile.am (MODULES): Add new file.

The goal here is to override packages in build system arguments, right?
This is great and we really need something like this to make building
package variants simpler.  (I ran into a problem that would be solved by
this when I tried to build Perl modules for different variants of Perl.)

Looking over the patch it feels inelegant to have a whitelist of
permitted arguments, as in “compiler-keyword”.  We already have a
procedure called “package-input-rewriting” that replaces any (explicit
input-) package in the dependency graph with a different package.  What
I like about that is that it is generic.  Is there a way we could extend
it to include packages pulled in by the build system, e.g. by making it
work at the level of bags?

--
Ricardo

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