Re: package updater: operate on package structs, not names?

[Andreas Enge]

On Tue, Dec 01, 2015 at 11:41:25AM +0100, Ricardo Wurmus wrote:
> There are two ways to approach this: we change the Guix package names to
> closely match those of the upstream packages, or we pass the complete
> package structure to ‘latest-release’.  The latter approach would allow
> the CRAN updater to extract the appropriate name from the tarball URI.

I think we should work on the package, or more concretely, the uri and
the version. Then we should do some pattern matching to find occurrences
of major-minor-patchlevel, major-minor or major versions in the uri.
And then we should try +1 in each of them (with later components set to 0).

For instance with qt:
    (version "5.5.1")
             (uri
               (string-append
                 "http://download.qt.io/official_releases/qt/";
                 (version-major+minor version)
                 "/" version
                 "/single/qt-everywhere-opensource-src-"
                 version ".tar.xz"))
which expands to
http://download.qt.io/official_releases/qt/5.5/5.5.1/single/qt-everywhere-opensource-src-5.5.1.tar.xz

we should try
http://download.qt.io/official_releases/qt/5.5/5.5.2/single/qt-everywhere-opensource-src-5.5.2.tar.xz
http://download.qt.io/official_releases/qt/5.6/5.6.0/single/qt-everywhere-opensource-src-5.6.0.tar.xz
http://download.qt.io/official_releases/qt/6.0/6.0.0/single/qt-everywhere-opensource-src-6.6.0.tar.xz
(and maybe some recursion to find the latest version).

What do you think?

Andreas