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From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: "René Scharfe" <l.s.r@web.de>, "Git List" <git@vger.kernel.org>
Subject: Re: [PATCH] describe: fix --no-exact-match
Date: Tue, 08 Aug 2023 18:43:41 -0700	[thread overview]
Message-ID: <xmqqzg3156sy.fsf@gitster.g> (raw)
In-Reply-To: <20230808212720.GA760752@coredump.intra.peff.net> (Jeff King's message of "Tue, 8 Aug 2023 17:27:20 -0400")

Jeff King <peff@peff.net> writes:

> On Fri, Jul 21, 2023 at 03:41:33PM +0200, René Scharfe wrote:
>
>> +static int option_parse_exact_match(const struct option *opt, const char *arg,
>> +				    int unset)
>> +{
>> +	BUG_ON_OPT_ARG(arg);
>> +
>> +	max_candidates = unset ? DEFAULT_CANDIDATES : 0;
>> +	return 0;
>> +}
>
> I wanted to call out a style question here. The "opt" parameter is
> unused, since it manipulates the "max_candidates" global directly. I can
> add an UNUSED annotation to satisfy -Wunused-parameter, but in such
> cases I've usually been modifying them like:
>
>   int *value = opt->value;
>   ...
>   *value = unset ? DEFAULT_CANDIDATES : 0;
>
> so that the callback operates on the value passed in the options list.

Yeah, I wasn't paying attention to that particular detail, but I
tend to think that using opt->value to point at the variable would
make sense here.  That approach matches what is internally done by
OPT_STRING_LIST() and OPT_STRVEC(), the built-in types that are
implemented via the same OPTION_CALLBACK mechanism.

One good thing about it is that it makes it clear, without looking
at the implementation of the callback function, which variables are
affected only by looking at what OPT_CALLBACK() says.

> So before I sent a patch (either to switch to using opt->value, or to
> add an UNUSED annotation), I wanted to see what you (or others) thought
> between the two. I.e., should we have a rule of "try not to operate on
> global data via option callbacks" or is that just being too pedantic for
> one-off callbacks like this?

So, that was my preference, but I may be missing some obvious
downsides.  I am interested in hearing from René, who often shows
better taste than I do in these cases ;-)

Thanks.

  parent reply	other threads:[~2023-08-09  1:43 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-18 15:44 [PATCH] ls-tree: fix --no-full-name René Scharfe
2023-07-18 16:37 ` Junio C Hamano
2023-07-18 20:49   ` Junio C Hamano
2023-07-21 12:41     ` René Scharfe
2023-07-21 12:41   ` René Scharfe
2023-07-21 14:37     ` Junio C Hamano
2023-07-21 19:29       ` René Scharfe
2023-07-21 20:09         ` Junio C Hamano
2023-07-21 20:14           ` Junio C Hamano
2023-07-24 12:29           ` René Scharfe
2023-07-24 18:51             ` Junio C Hamano
2023-07-24 20:09               ` René Scharfe
2023-07-24 20:50                 ` Junio C Hamano
2023-07-28  6:12                   ` René Scharfe
2023-07-28  9:45                     ` Phillip Wood
2023-07-29 20:40                       ` René Scharfe
2023-07-31 15:31                         ` Junio C Hamano
2023-08-04 16:40                           ` Junio C Hamano
2023-08-04 19:48                             ` Phillip Wood
2023-08-05 10:40                               ` René Scharfe
2023-07-24 12:29           ` [PATCH v2 0/5] show negatability of options in short help René Scharfe
2023-07-24 12:34             ` [PATCH v2 1/5] subtree: disallow --no-{help,quiet,debug,branch,message} René Scharfe
2023-07-24 12:36             ` [PATCH v2 2/5] t1502, docs: disallow --no-help René Scharfe
2023-07-24 12:38             ` [PATCH v2 3/5] t1502: move optionspec help output to a file René Scharfe
2023-07-24 12:39             ` [PATCH v2 4/5] t1502: test option negation René Scharfe
2023-07-24 12:40             ` [PATCH v2 5/5] parse-options: show negatability of options in short help René Scharfe
2023-08-05 14:33           ` [PATCH v3 0/8] " René Scharfe
2023-08-05 14:37             ` [PATCH v3 1/8] subtree: disallow --no-{help,quiet,debug,branch,message} René Scharfe
2023-08-05 14:37             ` [PATCH v3 2/8] t1502, docs: disallow --no-help René Scharfe
2023-08-05 14:38             ` [PATCH v3 3/8] t1502: move optionspec help output to a file René Scharfe
2023-08-05 14:39             ` [PATCH v3 4/8] t1502: test option negation René Scharfe
2023-08-05 14:40             ` [PATCH v3 5/8] parse-options: show negatability of options in short help René Scharfe
2023-08-05 14:43             ` [PATCH v3 6/8] parse-options: factor out usage_indent() and usage_padding() René Scharfe
2023-08-05 14:44             ` [PATCH v3 7/8] parse-options: no --[no-]no- René Scharfe
2023-08-05 14:52             ` [PATCH v3 8/8] parse-options: simplify usage_padding() René Scharfe
2023-08-05 23:04               ` Junio C Hamano
2023-07-21 12:41   ` [PATCH] show-branch: fix --no-sparse René Scharfe
2023-07-21 14:42     ` Junio C Hamano
2023-07-21 16:30       ` René Scharfe
2023-07-21 12:41   ` [PATCH] show-branch: disallow --no-{date,topo}-order René Scharfe
2023-07-21 12:41   ` [PATCH] reset: disallow --no-{mixed,soft,hard,merge,keep} René Scharfe
2023-07-21 12:41   ` [PATCH] pack-objects: fix --no-quiet René Scharfe
2023-07-21 12:41   ` [PATCH] pack-objects: fix --no-keep-true-parents René Scharfe
2023-07-21 17:03     ` Junio C Hamano
2023-07-21 12:42   ` [PATCH] branch: disallow --no-{all,remotes} René Scharfe
2023-07-21 12:42   ` [PATCH] am: unify definition of --keep-cr and --no-keep-cr René Scharfe
2023-07-21 13:41   ` [PATCH] describe: fix --no-exact-match René Scharfe
2023-07-21 14:10     ` Junio C Hamano
2023-07-21 17:00     ` Junio C Hamano
2023-08-08 21:27     ` Jeff King
2023-08-08 21:28       ` Jeff King
2023-08-09  1:43       ` Junio C Hamano [this message]
2023-08-09 14:09         ` Jeff King
2023-08-09 16:41           ` René Scharfe
2023-08-09 19:07             ` Junio C Hamano
2023-08-10  0:26               ` Jeff King
2023-08-10  1:00                 ` Junio C Hamano
2023-08-10 19:45                   ` René Scharfe
2023-08-10  0:41             ` Jeff King
2023-08-10 19:10               ` René Scharfe
2023-08-11 15:11                 ` Jeff King
2023-08-11 17:59                   ` René Scharfe
2023-08-11 18:24                     ` Jeff King
2023-08-12  5:11                       ` René Scharfe
2023-08-11 15:13                 ` Jeff King
2023-08-11 17:59                   ` René Scharfe

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