Re: [PATCH 0/3] Add a generalized `wrap-language-programs`

[Alex Sassmannshausen]

Hi Leo,

Leo Famulari writes:

> On Thu, Nov 17, 2016 at 04:58:45PM +0100, Alex Sassmannshausen wrote:
>> 
>> Hello
>> 
>> > You may try e.g. scons, pip, sphinx, or youtube-dl.
>> 
>> Hartmut was kind enough to suggest the above python applications to test
>> this `wrap-language-programs` patch set against, however I have been
>> stuck in "Rebuild the world"-hell for the last day and a half setting up
>> testcases.
>> 
>> I end up feeling a bit desesperated and incompetent, as I'm sure it's
>> not supposed to be this hard to create an appropriate test scenario here
>> — so I was wondering whether anyone has any pointers in avoiding
>> constantly rebuilding the world?
>
> Most of the Guix distribution depends on Perl, and most of the rest
> depends on Python ;)
>
> Try `guix refresh -l perl`.
>
> So, changing the build systems for these languages will require you to
> rebuild almost everything.

Thank you for pointing this out.  As I took a walk yesterday evening it
slowly started to dawn on me that something like this might be going on!
It's super useful to have this confirmed as the cause though: it gave me
that satisfying feeling of pieces of a larger puzzle falling into place
in my head :-)

> Changes like this will need to go on the core-updates branch, where we
> make changes to the core of the system.

Makes sense, I will push it to core-updates tonight.

> You could create a separate perl-test-build-system and use it for your
> test packages.

I guess this would mean that 'the world' would still depend on the
unchanged build system, thus being substitutable, and only my test
packages needing to be rebuilt with the changed build system.  That
makes a lot of sense.  Cheers!

With a new sense of clarity,

Alex