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Subject: |
[PATCH 0/1] Introducing 'with-parameters' for gexp dynamic binding |
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Date: |
Fri, 6 Mar 2020 11:41:08 +0100 |
Hello Guix!
This patch adds a new ‘with-parameters’ form. It is like ‘parameterize’
except that it takes effect when a file-like object is lowered, as in:
;; Return coreutils for i686.
(with-parameters ((%current-system "i686-linux"))
coreutils)
‘with-parameters’ is necessary because if you would use ‘parameterize’
in the example above, it wouldn’t have any effect at all: the dynamic
binding would be installed at the wrong time.
It works for any SRFI-39 parameter, though ‘%current-system’ is my main
use case. It makes it possible to have gexps or manifests that include
things explicitly targeting a given system. (For instance, I’d like to
have a manifest for release-critical things that explicitly pins the
targeted systems.)
Note that ‘with-parameters’ applies to file-like objects; it is _not_ a
property of the gexp itself. So one cannot, for example, write:
(with-parameters ((%current-system "i686-linux"))
#~(a b c d))
I feel like it’s better this way, though it could be confusing.
Thoughts?
Besides, ‘with-parameters’ is the dual of what was discussed at
<https://issues.guix.gnu.org/issue/29296>.
Thanks,
Ludo’.
Ludovic Courtès (1):
gexp: Add 'with-parameters'.
.dir-locals.el | 1 +
doc/guix.texi | 19 ++++++++++++++++
guix/gexp.scm | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
tests/gexp.scm | 28 ++++++++++++++++++++++++
4 files changed, 107 insertions(+)
--
2.25.1
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--- Begin Message ---
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Subject: |
Re: [bug#39945] [PATCH 0/1] Introducing 'with-parameters' for gexp dynamic binding |
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Date: |
Thu, 12 Mar 2020 18:34:03 +0100 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) |
Hi Mathieu,
Mathieu Othacehe <address@hidden> skribis:
>> Thoughts?
>>
>> Besides, ‘with-parameters’ is the dual of what was discussed at
>> <https://issues.guix.gnu.org/issue/29296>.
>
> Super nice! Maybe you could add a test-case involving
> %current-target-system but otherwise this LGTM.
Done and pushed as cf2ac04f13d9266c7c8a2ebd2e85ef593231ac9d.
> Do you think we could use this to get around this issue we discussed
> there:
> https://lists.gnu.org/archive/html/guix-devel/2019-12/msg00099.html.
It could be use to achieve the same result as the <native-qemu> package
you proposed:
#~(… #+(with-parameters ((%current-system %system)) qemu) …)
However, the issue I mentioned before with this approach remain:
[…] now the result of:
guix system build -s armhf-linux -d …
would be dependent on the actual system type. In other words, the
result would be different if you run it on armhf-linux, if you run it on
x86_64-linux, or if you run it on i686-linux. Not great.
Thanks for your feedback!
Ludo’.
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