Re: [PATCH 1/2] import: json: Silence json-fetch output.

[ludo@gnu.org (Ludovic Courtès)]

Eric Bavier <bavier@member.fsf.org> skribis:

> * guix/import/json.scm (json-fetch): Use http-fetch instead of url-fetch
> to avoid writing to stdout and a temporary file for each invocation.
> * guix/import/gem.scm (rubygems-fetch): Do not redirect json-fetch
> output to /dev/null.
> * guix/import/pypi.scm (pypi-fetch): Likewise.

[...]

>  (define (json-fetch url)
>    "Return an alist representation of the JSON resource URL, or #f on failure."
> -  (call-with-temporary-output-file
> -   (lambda (temp port)
> -     (and (url-fetch url temp)
> -          (hash-table->alist
> -           (call-with-input-file temp json->scm))))))
> +  (and=> (false-if-exception (http-fetch url))
> +         (lambda (port)
> +           (let ((result (hash-table->alist (json->scm port))))
> +             (close-port port)
> +             result))))

It’d be better to not catch exceptions raised by ‘http-fetch’ here.
Instead they’d be caught at the top level and a detailed error message
would be displayed, which is always better than silently ignoring
issues.

However we’d need to check if there are uses where this is a problem.
For example, there might be updaters or importers that assume that #f
means that the package doesn’t exist or something like that.

WDYT?

> diff --git a/guix/import/pypi.scm b/guix/import/pypi.scm
> index 68153d5..9794ff9 100644
> --- a/guix/import/pypi.scm
> +++ b/guix/import/pypi.scm
> @@ -51,14 +51,8 @@
>  (define (pypi-fetch name)
>    "Return an alist representation of the PyPI metadata for the package NAME,
>  or #f on failure."
> -  ;; XXX: We want to silence the download progress report, which is especially
> -  ;; annoying for 'guix refresh', but we have to use a file port.
> -  (call-with-output-file "/dev/null"
> -    (lambda (null)
> -      (with-error-to-port null
> -        (lambda ()
> -          (json-fetch (string-append "https://pypi.python.org/pypi/"
> -                                     name "/json")))))))
> +  (json-fetch (string-append "https://pypi.python.org/pypi/"
> +                             name "/json")))

The rest LGTM, thanks!

Ludo’.