Re: Enhanced 'warning'

[Ludovic Courtès]

Nikita Karetnikov <address@hidden> skribis:

>> I think it’d be nice to have a ‘warning’ procedure in (guix ui), so
>> things are uniform.
>
> It think it might be better to have a single 'warning' macro which could
> handle several cases (errors, warnings and similar things).  (Actually,
> 'guix hash' should use errors, not warnings.)

Yes, you’re right.

> Here is a simplified version:
>
> (define-syntax define-output-macro

Rather: ‘define-diagnostic’.

>   (syntax-rules ()
>     ((_ name prefix)
>      (define-syntax name
>        (lambda (x)
>          (syntax-case x (_ N_)
>            ((name (_ str))
>             (with-syntax ((prefix (datum->syntax x prefix)))
>               #'(display (string-append prefix str "\n"))))
>            ((name (N_ str1 str2))
>             (with-syntax ((prefix (datum->syntax x prefix)))
>               #'(display (string-append prefix str1 str2 "\n"))))))))))

You should reuse the body of the current ‘warning’ macro, though.

> (define-output-macro warning "warning: ")
> (define-output-macro error* "error: ")

You could use ‘report-error’ to avoid name clashes.

But I think ‘leave’ should be enough, no?

> scheme@(guile-user)> (warning (_ "foo"))
> warning: foo
>
> scheme@(guile-user)> (error* (N_ "foo" "bar"))
> error: foobar

Note that ‘N_’ is meant to be an alias for ‘ngettext’, so the above form
is invalid.

> And here is a problem...  Is it possible to compose a macro (e.g.,
> 'error*') with (exit 1) without touching the internals of
> 'define-output-macro'?

What about:

  (define-syntax-rule (leave args ...)
    (begin
      (error* args ...)
      (exit 1)))

Thanks,
Ludo’.