Re: how to customize mirror list used in custom channels?

[zimoun]

Hi,

On Mon, 28 Nov 2022 at 11:49, Ludovic Courtès <ludo@gnu.org> wrote:
> Hi,
>
> zimoun <zimon.toutoune@gmail.com> skribis:
>
>> On Sat, 26 Nov 2022 at 12:11, Ludovic Courtès <ludo@gnu.org> wrote:
>
> [...]
>
>>> Now, if you really want to extend the set of things recognized, you
>>> could write variant of ‘url-fetch’ that passes a different #:mirrors
>>> argument to ‘built-in-download’.  Maybe ‘url-fetch’ could have a
>>> #:mirrors parameter to simplify it.
>>
>> Why is it not possible to extend ’%mirrors?
>
> What I described above is one way to extend it, just not via ‘set!’.

Just to be sure, one way is this extension mechanism,

--8<---------------cut here---------------start------------->8---
(define (qt-urls component version)
  "Return a list of URLs for VERSION of the Qt5 COMPONENT."
  ;; We can't use a mirror:// scheme because these URLs are not exact copies:
  ;; the layout differs between them.
  (list (string-append "https://download.qt.io/official_releases/qt/";
                       (version-major+minor version) "/" version
                       "/submodules/" component "-everywhere-opensource-src-"
                       version ".tar.xz")
        (string-append "https://download.qt.io/official_releases/qt/";
                       (version-major+minor version) "/" version
                       "/submodules/" component "-everywhere-src-"
                       version ".tar.xz")
        (string-append "https://download.qt.io/archive/qt/";
                       (version-major+minor version) "/" version
                       "/submodules/" component "-everywhere-opensource-src-"
                       version ".tar.xz")
        (let ((directory (string-append "qt5" (string-drop component 2))))
          (string-append "http://sources.buildroot.net/"; directory "/"
                         component "-everywhere-opensource-src-" version 
".tar.xz"))
        (string-append "https://distfiles.macports.org/qt5/";
                       component "-everywhere-opensource-src-" version 
".tar.xz")))
--8<---------------cut here---------------end--------------->8---

then,

    (uri (qt-urls name version))

Right?  Well, for what it is worth, it does not appear to me consistent
with the rest.  We could do the same for everything, and remove
"mirror://" after all. :-)

The other one way is to implement a variant of url-fetch method.  What
would be the interface?  Where the extended list of mirrors would be
provided?


Cheers,
simon