diff mbox series

[bug#77072,v1] channels: add transformer field

Message ID Z9g9hxAAk41ABXxZ@kernelpanicroom
State New
Headers
Series [bug#77072,v1] channels: add transformer field |

Commit Message

Jakob Kirsch March 17, 2025, 3:19 p.m. UTC 
  Hey everyone,
I've recently tried to declaratively apply my own patches to the upstream guix channel or channels in general but I found it very hard (aka impossible) to do that cleanly so I made this simple patch.

This patch adds a new "transformer" field to the channel record. That "transformer" is a lambda that is called right before applying the quirk patches with the checkout path being its only argument.

What do you think about my proposal?
From 36462095039632348ed5fbd5763426f74f48049f Mon Sep 17 00:00:00 2001
Message-ID: <36462095039632348ed5fbd5763426f74f48049f.1742224546.git.jakob.kirsch@web.de>
From: Jakob Kirsch <jakob.kirsch@web.de>
Date: Mon, 17 Mar 2025 14:53:07 +0100
Subject: [PATCH v1] channels: add transformer field

Change-Id: I46c065eb096d9fccefde7a791e4373a614deac33
---
 guix/channels.scm | 3 +++
 1 file changed, 3 insertions(+)


base-commit: 98be320183579b3d09cf4059e86a9781485628b4
--
2.48.1

Comments

Rutherther March 22, 2025, 10:13 a.m. UTC | #1 
Hello Jakob,

I also encountered this issue and would like a way to transform
channels. However, I have a few notes.

While looking through the code I noticed latest-channel-instance
has an argument called patches. This argument is already capable of
applying patches. Each patch has a predicate and application function,
First the predicate is ran to know if the patch is applicable,
and if so, then it's applied with the application function.

Wouldn't it make sense to rather than making a new mechanism,
extend the current one, by adding to channels a new field
that will hold list of `patch` records, and then in
latest-channels-instance we would just do

```
(apply-patches checkout commit (channel-patches patches))
```

?

Apart from that I am wondering if this is going to be user friendly,
because I would imagine most people will just want to patch with already
existing commits. And for that it would be much easier to just have a
list of files to apply, similar to what origin has.
While this will be possible with this transformer field, it will mean
calling the patch (or I could've missed a function that does that
already).
So maybe at least exposing a new procedure to apply a list of patches
would be good, so users can then just do something like:

```
(channel
  (patches ;; already expecting list of patch records
    (make-channel-patches
      (list (local-file "fix-1.patch")))))
```
Where make-channel-patches takes a list of files
and returns a patch record returning #t for predicate,
and applying by calling the patch executable for each file, similarly
to what patch-and-repack in guix/packages.scm does.
Note that I am not sure if local-file is appropriate here
or if gexps are unusable.

What do you think?

Regards,
Rutherther
diff mbox series

Patch

diff --git a/guix/channels.scm b/guix/channels.scm
index 4700f7a45d..091a5c2f16 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -135,6 +135,7 @@  (define-record-type* <channel> channel make-channel
   (branch    channel-branch (default "master"))
   (commit    channel-commit (default #f))
   (introduction channel-introduction (default #f))
+  (transformer channel-transformer (default (lambda checkout #t)))
   (location  channel-location
              (default (current-source-location)) (innate)))

@@ -456,6 +457,8 @@  (define* (latest-channel-instance store channel
 thus potentially malicious code.")))))))))
         (warning (G_ "channel authentication disabled~%")))

+    (apply (channel-transformer channel) (list checkout))
+
     (when (guix-channel? channel)
       ;; Apply the relevant subset of PATCHES directly in CHECKOUT.  This is
       ;; safe to do because 'switch-to-ref' eventually does a hard reset.