From: Jeff King <peff@peff.net>
To: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH v2 2/3] parse-options: make OPT_ARGUMENT() more useful
Date: Thu, 14 Mar 2019 23:15:53 -0400 [thread overview]
Message-ID: <20190315031553.GB28943@sigill.intra.peff.net> (raw)
In-Reply-To: <10775638ad8f2ef9b64b8dbaf71b80d8546e81d8.1552562701.git.gitgitgadget@gmail.com>
On Thu, Mar 14, 2019 at 04:25:04AM -0700, Johannes Schindelin via GitGitGadget wrote:
> diff --git a/Documentation/technical/api-parse-options.txt b/Documentation/technical/api-parse-options.txt
> index 2b036d7838..2e2e7c10c6 100644
> --- a/Documentation/technical/api-parse-options.txt
> +++ b/Documentation/technical/api-parse-options.txt
> @@ -198,8 +198,10 @@ There are some macros to easily define options:
> The filename will be prefixed by passing the filename along with
> the prefix argument of `parse_options()` to `prefix_filename()`.
>
> -`OPT_ARGUMENT(long, description)`::
> +`OPT_ARGUMENT(long, &int_var, description)`::
> Introduce a long-option argument that will be kept in `argv[]`.
> + If this option was seen, `int_var` will be set to one (except
> + if a `NULL` pointer was passed).
So this effectively makes it into a "bool" that we keep. I think that's
fine. It always uses NOARG, so it is not like we would ever need to see
"we got --foo, and this is the argument it had".
I did wonder if it was possible for "--no-foo" to trigger this (leaving
the caller who looks at the int unsure if they saw "--foo" or
"--no-foo"), but it seems that the parse-options code checks for
OPTION_ARGUMENT before it ever looks at negation.
Curiously, it also checks it before doing the usual prefix-matching
magic. So you could otherwise say "--no-inde", but OPT_ARGUMENT() will
not allow it. I think that's probably sane and not worth thinking
further about, but it is an interesting quirk that a user could possibly
run into.
> diff --git a/parse-options.c b/parse-options.c
> index cec74522e5..1d57802da0 100644
> --- a/parse-options.c
> +++ b/parse-options.c
> @@ -286,6 +286,8 @@ static enum parse_opt_result parse_long_opt(
> optname(options, flags));
> if (*rest)
> continue;
> + if (options->value)
> + *(int *)options->value = options->defval;
Cute. You could actually assign any defval you like, though of course
the convenient OPT_ARGUMENT() macro just always uses 1.
I wondered if you might need another cast for defval itself, but it's an
intptr_t (so it's the types that use it as a string that need to cast to
"const char *").
This looks very clean overall, and I agree it's much nicer than the
alternatives for your use case.
-Peff
next prev parent reply other threads:[~2019-03-15 3:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-13 19:20 [PATCH 0/2] Allow difftool to be run outside of Git worktrees Johannes Schindelin via GitGitGadget
2019-03-13 19:20 ` [PATCH 2/2] difftool: allow running outside Git worktrees with --no-index Johannes Schindelin via GitGitGadget
2019-03-13 20:46 ` Jeff King
2019-03-14 12:16 ` Johannes Schindelin
2019-03-15 3:08 ` Jeff King
2019-03-13 19:20 ` [PATCH 1/2] difftool: remove obsolete (and misleading) comment Johannes Schindelin via GitGitGadget
2019-03-14 11:25 ` [PATCH v2 0/3] Allow difftool to be run outside of Git worktrees Johannes Schindelin via GitGitGadget
2019-03-14 11:25 ` [PATCH v2 1/3] difftool: remove obsolete (and misleading) comment Johannes Schindelin via GitGitGadget
2019-03-14 11:25 ` [PATCH v2 2/3] parse-options: make OPT_ARGUMENT() more useful Johannes Schindelin via GitGitGadget
2019-03-15 3:15 ` Jeff King [this message]
2019-03-15 13:24 ` Johannes Schindelin
2019-03-18 2:47 ` Junio C Hamano
2019-03-18 21:04 ` Jeff King
2019-03-19 0:25 ` Junio C Hamano
2019-03-14 11:25 ` [PATCH v2 3/3] difftool: allow running outside Git worktrees with --no-index Johannes Schindelin via GitGitGadget
2019-03-15 3:17 ` Jeff King
2019-03-15 13:20 ` Johannes Schindelin
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