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From: Christian Couder <christian.couder@gmail.com>
To: Jeff King <peff@peff.net>
Cc: git <git@vger.kernel.org>, Junio C Hamano <gitster@pobox.com>,
	Donald R Laster Jr <laster@dlaster.com>,
	Jacob Keller <jacob.keller@gmail.com>,
	Christian Couder <chriscool@tuxfamily.org>
Subject: Re: [PATCH v3 1/7] git-compat-util: introduce skip_to_optional_arg()
Date: Mon, 11 Dec 2017 06:56:03 +0100	[thread overview]
Message-ID: <CAP8UFD26ZJQWtfzETHXjPoKWyL0f3qEuimohVysYo0WtmpSyBg@mail.gmail.com> (raw)
In-Reply-To: <20171210143914.GA19894@sigill.intra.peff.net>

On Sun, Dec 10, 2017 at 3:39 PM, Jeff King <peff@peff.net> wrote:
> On Sun, Dec 10, 2017 at 09:31:18AM -0500, Jeff King wrote:
>
>> On Sat, Dec 09, 2017 at 09:40:07PM +0100, Christian Couder wrote:
>>
>> > The changes compared to v2 are:
>> >
>> >   - s/_val/_arg/ in the name of the functions
>> >   - s/val/arg/ in the name of the third argument of the functions
>> >   - works with NULL as third argument of the functions
>>
>> This whole series looks OK to me, but this third point made me wonder:
>> what would be the use of allowing NULL for the "arg" parameter?
>>
>> I didn't see any use of this in the series, and I'm having trouble
>> figuring out how it would be useful. E.g., if I do:
>>
>>   if (skip_to_optional_arg(arg, "--foo", NULL))
>>      ...
>>
>> what can I do in "..."? I know we matched _some_ type of "--foo", but I
>> cannot know whether it was "--foo" or "--foo=bar", nor what "bar" is. It
>> could only be used by some kind of vague validator to say "well, at
>> least this looks like an option that I _could_ parse if I wanted to".
>>
>> So I guess I don't mind it, as it does the most reasonable thing it can
>> when passed NULL, but I would be surprised if we ever actually exercise
>> the code path.
>
> And of course as soon as I sent this, I went back and double-checked.
> And indeed I totally missed this call:
>
>   +       else if (starts_with(arg, "-B") ||
>   +                skip_to_optional_arg(arg, "--break-rewrites", NULL)) {
>           if ((options->break_opt = diff_scoreopt_parse(arg)) == -1)

Yeah, calls like this were discussed in:
https://public-inbox.org/git/xmqqh8t6o9me.fsf@gitster.mtv.corp.google.com/

> So that's kind-of weird, because we are parsing "-B", etc, and then
> expecting it to be _reparsed_ by diff_scoreopt_parse. So the two
> callsites must always match. IMHO this ought to do either:
>
>   - we should just ask diff_scoreopt_parser to tell us if this was a
>     valid option that it understood
>
> or
>
>   - parse up to the "=", and then ask the scoreopt parser to parse the
>     remainder. This would require us passing 'B'/'C'/'M' to the
>     function ourselves, I think that's a better pattern. It means we
>     could reuse the parser for things like config values if we wanted to
>     (our current diff.renames is a bool, but it would not be
>     unreasonable for it to take a score).
>
> None of that is a mess of your creation, though, so I'm OK punting on it
> for now.

Yeah, this could be part of the #leftoverbits.

  reply	other threads:[~2017-12-11  6:04 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-09 20:40 [PATCH v3 1/7] git-compat-util: introduce skip_to_optional_arg() Christian Couder
2017-12-09 20:40 ` [PATCH v3 2/7] index-pack: use skip_to_optional_arg() Christian Couder
2017-12-09 20:40 ` [PATCH v3 3/7] diff: " Christian Couder
2017-12-09 20:40 ` [PATCH v3 4/7] diff: use skip_to_optional_arg_default() Christian Couder
2017-12-09 20:40 ` [PATCH v3 5/7] diff: use skip_to_optional_arg_default() in parsing --relative Christian Couder
2017-12-09 20:40 ` [PATCH v3 6/7] diff: add tests for --relative without optional prefix value Christian Couder
2017-12-09 20:40 ` [PATCH v3 7/7] t4045: reindent to make helpers readable Christian Couder
2017-12-10 14:31 ` [PATCH v3 1/7] git-compat-util: introduce skip_to_optional_arg() Jeff King
2017-12-10 14:39   ` Jeff King
2017-12-11  5:56     ` Christian Couder [this message]
2017-12-11 23:23     ` Junio C Hamano

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