Re: [PATCH 4/7] revision, rev-parse: factorize incompatibility messages about --exclude-hidden

["René Scharfe" <l.s.r@web.de>]

Am 06.12.23 um 15:39 schrieb Patrick Steinhardt:
> On Wed, Dec 06, 2023 at 03:21:15PM +0100, René Scharfe wrote:
>> Am 06.12.23 um 14:08 schrieb Patrick Steinhardt:
>>> On Wed, Dec 06, 2023 at 12:51:58PM +0100, René Scharfe wrote:
>>>> Use the standard parameterized message for reporting incompatible
>>>> options to report options that are not accepted in combination with
>>>> --exclude-hidden.  This reduces the number of strings to translate and
>>>> makes the UI a bit more consistent.
>>>>
>>>> Signed-off-by: René Scharfe <l.s.r@web.de>
>>>> ---
>>>>  builtin/rev-parse.c                |  9 ++++++---
>>>>  revision.c                         | 18 ++++++++++++------
>>>>  t/t6018-rev-list-glob.sh           |  6 ++----
>>>>  t/t6021-rev-list-exclude-hidden.sh |  4 ++--
>>>>  4 files changed, 22 insertions(+), 15 deletions(-)
>>>>
>>>> diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
>>>> index fde8861ca4..917f122440 100644
>>>> --- a/builtin/rev-parse.c
>>>> +++ b/builtin/rev-parse.c
>>>> @@ -893,13 +893,15 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
>>>>  			}
>>>>  			if (opt_with_value(arg, "--branches", &arg)) {
>>>>  				if (ref_excludes.hidden_refs_configured)
>>>> -					return error(_("--exclude-hidden cannot be used together with --branches"));
>>>> +					return error(_("options '%s' and '%s' cannot be used together"),
>>>> +						     "--exclude-hidden", "--branches");
>>>
>>> The repetitive nature of this patch and subsequent ones made me wonder
>>> whether it would be useful to have a function similar to the
>>> `die_for_incompatible_*()` helper that knows to format this error
>>> correctly.
>>
>> I wondered the same and experimented with a die_for_incompatible_opt2().
>> It would allow the compiler to detect typos.
>>
>> Passing in the conditions as parameters is a bit tedious and unlike its
>> for its higher-numbered siblings there is not much to win by doing that
>> instead of using an if statement or two nested ones.  We could pass in
>> 1 if we want to integrate that function into an if cascade like above,
>> but it would look a bit silly.  And here we'd need a non-fatal version
>> anyway.
>
> Maybe the easiest solution would be to have `error_incompatible_usage()`
> that simply wraps `error()`.

Yes, but having two variants (die_ and error_) is unfortunate.

> You'd pass in the incompatible params and
> it makes sure to format them accordingly. It could either accept two
> args or even be a vararg function with sentinel `NULL`.

Tempting, but passing the conditions separately is actually useful to
improve the shown message when there are more than two options.

> It's not perfect
> of course, but would at least ensure that we can easily convert things
> over time without having to duplicate the exact message everywhere.

Maybe the simplest option would be to use a macro, e.g.

   #define INCOMPATIBLE_OPTIONS_MESSAGE \
           _("options '%s' and '%s' cannot be used together")

It could be used with both error() and die(), and the compiler would
still ensure that two strings are passed along with it, but I don't know
how to encode that requirement in the macro name somehow to make it
self-documenting.  Perhaps by getting the number two in there?

> I don't think it's a problem to not convert everything in one go. The
> current series is a good step in the right direction, and any additional
> instances that were missed can be fixed in follow-ups.

Right; whatever we do, we can (and should) do it step by step.

René