[bug#45984] [PATCH 0/5] Fix recursive importers

["Ludovic Courtès" <ludo@gnu.org>]

Hi!

zimoun <zimon.toutoune@gmail.com> skribis:

> This corner case #1 happens when the package does not exist; then the function
> 'lookup-node' is not able to "unpack" the 'values' and throw and ugly
> backtrace, as exposed in bug#44114 <http://issues.guix.gnu.org/44115#3>.
>
> With these trivial patches, it is fixed for all the importers except 'opam'
> (because of 'and-let' which needs some care).

Neat!

> Now, instead of throwing an ugly backtrace, it simply say almost nothing:
>
> $ ./pre-inst-env guix import cran do-not-exist -r
> error: failed to retrieve package information from "https://cran.r-project.org/web/packages/do-not-exist/DESCRIPTION": 404 ("Not Found")
>
> $ ./pre-inst-env guix import pypi do-not-exist -r
> following redirection to `https://pypi.org/pypi/do-not-exist/json/'...
> #f
>
>
> This non-existent message is because the error is poorly handled.  With the 4
> patches, the situation is the same as "guix import gem" for all the importers
> with the recursive option.  One way for a better error handling is done in the
> last commit for 'guix import gem' only; the same trick can be done for all.
>
> $ guix import gem do-not-exist -r
> #f
>
> $ ./pre-inst-env guix import gem do-not-exist -r
> guix import: error: failed to download meta-data for package 'do-not-exist'

I think we do want this error message.  Why should we ignore
non-existent packages when doing ‘-r’?  It would think they’re still a
problem, no?

> In my opinions, UI messages should not appear in guix/import/*.scm but only in
> guix/scripts/*.scm.

I agree with the general idea, though sometimes taking this shortcut is
beneficial (maybe not in this case?).

> If I understand correctly, then the way the errors are reported could be
> uniformized between all the importers, and maybe the snippet in the subcommands
> "guix import <from>" could be refactorized a bit.

Probably.  ‘-r’ started as an option specific to one importer, but now
that most of them (?) support it, it’d make sense to rethink the
interfaces.

Thanks for looking into it!

Ludo’.