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From: Phillip Wood <phillip.wood123@gmail.com>
To: "Đoàn Trần Công Danh" <congdanhqx@gmail.com>,
	"René Scharfe" <l.s.r@web.de>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	git@vger.kernel.org, "Junio C Hamano" <gitster@pobox.com>,
	"Jeff King" <peff@peff.net>, "Taylor Blau" <me@ttaylorr.com>,
	"SZEDER Gábor" <szeder.dev@gmail.com>,
	"Lukáš Doktor" <ldoktor@redhat.com>,
	"Johannes Schindelin" <Johannes.Schindelin@gmx.de>
Subject: Re: [PATCH 09/13] parse-options API: don't restrict OPT_SUBCOMMAND() to one *_fn type
Date: Sat, 5 Nov 2022 21:32:36 +0000	[thread overview]
Message-ID: <43ec357b-bbd2-6b17-58f4-676a8c5e1749@dunelm.org.uk> (raw)
In-Reply-To: <Y2ZKHPkEXViv9wcp@danh.dev>

Hi Đoàn

On 05/11/2022 11:34, Đoàn Trần Công Danh wrote:
>   
> On 2022-11-05 09:32:44+0100, René Scharfe <l.s.r@web.de> wrote:
>> Why is this trickery needed?  Above you write that callbacks in
>> builtin/bisect--helper.c can't use subcommand_fn because they need
>> their own argument.  Can we extend subcommand_fn or use a global
>> variable to pass that extra thing instead?  The latter may be ugly, but
>> at least it's valid C..
> 
> Not the author, but I fully agree with you, I think instead of adding new API
> for some arbitrary subcommand_fn, I would change the subcommand_fn to
> type:
> 
> 	int (*)(int argc, const char **argv, const char *prefix, void *context)
> 
> The last argument would be an object pointer, which will be casted to
> the correct type inside the callback.
> 
> Let me cherry-picking this series on top of mine to see how things
> would progress.

Unfortunately the current implementation of OPT_SUBCOMMAND relies on 
returning a function pointer though a void* variable which while widely 
supported is undefined behavior. I wonder if an API like

typedef int (*subcommand_fn)(int, char**, char*);
typedef int (*subcommand_ctk_fn)(int, char**, char*, void*);
struct subcommand; /* opaque */

OPT_SUBCOMMAND(name, value, func);
OPT_SUMCOMMAND_CTX(name, value, func, ctx);

int call_subcommand(struct subcommand* subcommand, int argc, char** 
argv, char* prefix);


which would be used as

int sub1_fn(int argc, char** argv, char* prefix, void* ctx)
{
	struct cmd_ctx cmd_ctx = ctx
	...
}

int sub2_fn(int argc, char** argv, char* prefix)
{
	...
}

int cmd_foo(int argc, char** argv, char* prefix)
{
	struct cmd_ctx ctx = ...
	struct subcommand cmd = { 0 };
	...
	struct option opts[] = {
		OPT_SUBCOMMAND_CTX("sub1", &cmd, sub_fn, &ctx);
		OPT_SUBCOMMAND("sub2", &cmd, sub2_fn);
	};
	argc = parse_options(argc, argv, prefix, &opts, usage, flags);
	return call_subcommand(&cmd, argc, argv, prefix);
}


would be an improvement. One can avoid having to mark the ctx parameter 
as UNUSED() if a subcommand does not need any context by using 
OPT_SUBCOMMAND() rather than OPT_SUBCOMMAND_CTX().


The implementation of call_subcommand() would look something like

struct subcommand {
         void* ctx;
         int has_ctx;
         union {
                 subcommand_fn fn;
                 subcommand_ctx_fn ctx_fn;
         };
};

int call_subcommand(struct subcommand* subcommand, int argc, char 
**argv, char* prefix)
{
         if (subcommand->has_ctx)
                 return subcommand->ctx_fn(argc, argv, prefix, 
subcommand->ctx);
         else
                 return subcommand->fn(argc, argv, prefix);
}


Best Wishes

Phillip

  reply	other threads:[~2022-11-05 21:32 UTC|newest]

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-04  6:31 "git bisect run" strips "--log" from the list of arguments Lukáš Doktor
2022-11-04  9:45 ` Jeff King
2022-11-04 11:10   ` Đoàn Trần Công Danh
2022-11-04 12:51     ` Jeff King
2022-11-04 11:36   ` Ævar Arnfjörð Bjarmason
2022-11-04 12:45     ` Jeff King
2022-11-04 13:07       ` Ævar Arnfjörð Bjarmason
2022-11-04 12:37   ` SZEDER Gábor
2022-11-04 12:44     ` Jeff King
2022-11-04 11:40 ` [PATCH 0/3] Convert git-bisect--helper to OPT_SUBCOMMAND Đoàn Trần Công Danh
2022-11-04 11:40   ` [PATCH 1/3] bisect--helper: remove unused options Đoàn Trần Công Danh
2022-11-04 12:53     ` Jeff King
2022-11-04 11:40   ` [PATCH 2/3] bisect--helper: move all subcommands into their own functions Đoàn Trần Công Danh
2022-11-04 12:55     ` Jeff King
2022-11-04 13:32     ` Ævar Arnfjörð Bjarmason
2022-11-04 14:03       ` Đoàn Trần Công Danh
2022-11-04 11:40   ` [PATCH 3/3] bisect--helper: parse subcommand with OPT_SUBCOMMAND Đoàn Trần Công Danh
2022-11-04 13:00     ` Jeff King
2022-11-04 13:46     ` Ævar Arnfjörð Bjarmason
2022-11-04 14:07       ` Đoàn Trần Công Danh
2022-11-04 13:55   ` [PATCH 0/3] Convert git-bisect--helper to OPT_SUBCOMMAND Ævar Arnfjörð Bjarmason
2022-11-05 17:03   ` [PATCH v2 " Đoàn Trần Công Danh
2022-11-05 17:03     ` [PATCH v2 1/3] bisect--helper: remove unused options Đoàn Trần Công Danh
2022-11-05 17:03     ` [PATCH v2 2/3] bisect--helper: move all subcommands into their own functions Đoàn Trần Công Danh
2022-11-05 17:13       ` Đoàn Trần Công Danh
2022-11-05 17:03     ` [PATCH v2 3/3] bisect--helper: parse subcommand with OPT_SUBCOMMAND Đoàn Trần Công Danh
2022-11-05 17:07     ` [PATCH 00/13] Turn git-bisect to be builtin Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 01/13] bisect tests: test for v2.30.0 "bisect run" regressions Đoàn Trần Công Danh
2022-11-07 21:31         ` Ævar Arnfjörð Bjarmason
2022-11-08  1:17           ` Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 02/13] bisect: refactor bisect_run() to match CodingGuidelines Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 03/13] bisect--helper: pass arg[cv] down to do_bisect_run Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 04/13] bisect: fix output regressions in v2.30.0 Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 05/13] bisect run: keep some of the post-v2.30.0 output Đoàn Trần Công Danh
2022-11-07 21:40         ` Ævar Arnfjörð Bjarmason
2022-11-08  1:26           ` Đoàn Trần Công Danh
2022-11-08  3:11             ` Ævar Arnfjörð Bjarmason
2022-11-05 17:07       ` [PATCH 06/13] bisect--helper: remove unused arguments from do_bisect_run Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 07/13] bisect--helper: pretend we're real bisect when report error Đoàn Trần Công Danh
2022-11-07 21:29         ` Ævar Arnfjörð Bjarmason
2022-11-05 17:07       ` [PATCH 08/13] bisect test: test exit codes on bad usage Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 09/13] bisect--helper: emit usage for "git bisect" Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 10/13] bisect--helper: make `state` optional Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 11/13] bisect--helper: remove subcommand state Đoàn Trần Công Danh
2022-11-07 21:45         ` Ævar Arnfjörð Bjarmason
2022-11-08  1:27           ` Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 12/13] bisect--helper: log: allow arbitrary number of arguments Đoàn Trần Công Danh
2022-11-05 17:07       ` [PATCH 13/13] Turn `git bisect` into a full built-in Đoàn Trần Công Danh
2022-11-05 23:18     ` [PATCH v2 0/3] Convert git-bisect--helper to OPT_SUBCOMMAND Taylor Blau
2022-11-10 16:36   ` [PATCH v3 " Đoàn Trần Công Danh
2022-11-10 16:36     ` [PATCH v3 1/3] bisect--helper: remove unused options Đoàn Trần Công Danh
2022-11-11 12:42       ` Ævar Arnfjörð Bjarmason
2022-11-10 16:36     ` [PATCH v3 2/3] bisect--helper: move all subcommands into their own functions Đoàn Trần Công Danh
2022-11-11 13:51       ` Ævar Arnfjörð Bjarmason
2022-11-10 16:36     ` [PATCH v3 3/3] bisect--helper: parse subcommand with OPT_SUBCOMMAND Đoàn Trần Công Danh
2022-11-10 16:36     ` [PATCH v2 00/11] Turn git-bisect to be builtin Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 01/11] bisect tests: test for v2.30.0 "bisect run" regressions Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 02/11] bisect: refactor bisect_run() to match CodingGuidelines Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 03/11] bisect: fix output regressions in v2.30.0 Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 04/11] bisect run: keep some of the post-v2.30.0 output Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 05/11] bisect-run: verify_good: account for non-negative exit status Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 06/11] bisect--helper: identify as bisect when report error Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 07/11] bisect test: test exit codes on bad usage Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 08/11] bisect--helper: emit usage for "git bisect" Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 09/11] bisect--helper: handle states directly Đoàn Trần Công Danh
2022-11-10 16:36       ` [PATCH v2 10/11] bisect--helper: log: allow arbitrary number of arguments Đoàn Trần Công Danh
2022-11-11 14:01         ` Ævar Arnfjörð Bjarmason
2022-11-10 16:36       ` [PATCH v2 11/11] Turn `git bisect` into a full built-in Đoàn Trần Công Danh
2022-11-11 13:53         ` Ævar Arnfjörð Bjarmason
2022-11-11 15:37           ` Jeff King
2022-11-11 21:09             ` Ævar Arnfjörð Bjarmason
2022-11-11 22:07       ` [PATCH v2 00/11] Turn git-bisect to be builtin Taylor Blau
2022-11-15 19:18         ` Taylor Blau
2022-11-15 19:36           ` Jeff King
2022-11-15 19:40             ` Taylor Blau
2022-11-11 12:32     ` [PATCH v3 0/3] Convert git-bisect--helper to OPT_SUBCOMMAND Ævar Arnfjörð Bjarmason
2022-11-04 13:22 ` [PATCH 00/13] bisect: v2.30.0 "run" regressions + make it built-in Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 01/13] bisect tests: test for v2.30.0 "bisect run" regressions Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 02/13] bisect: refactor bisect_run() to match CodingGuidelines Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 03/13] bisect: fix output regressions in v2.30.0 Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 04/13] bisect run: fix "--log" eating regression " Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 05/13] bisect run: keep some of the post-v2.30.0 output Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 06/13] bisect test: test exit codes on bad usage Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 07/13] bisect--helper: emit usage for "git bisect" Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 08/13] bisect--helper: have all functions take state, argc, argv, prefix Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 09/13] parse-options API: don't restrict OPT_SUBCOMMAND() to one *_fn type Ævar Arnfjörð Bjarmason
2022-11-05  8:32     ` René Scharfe
2022-11-05 11:34       ` Đoàn Trần Công Danh
2022-11-05 21:32         ` Phillip Wood [this message]
2022-11-05 13:52       ` Ævar Arnfjörð Bjarmason
2022-11-05 16:36         ` Phillip Wood
2022-11-05 21:59           ` Ævar Arnfjörð Bjarmason
2022-11-05 17:26         ` René Scharfe
2022-11-05 22:33           ` Ævar Arnfjörð Bjarmason
2022-11-06  8:25             ` René Scharfe
2022-11-06 13:28               ` Ævar Arnfjörð Bjarmason
2022-11-12 10:42                 ` René Scharfe
2022-11-12 16:34                   ` Jeff King
2022-11-12 16:55                     ` Ævar Arnfjörð Bjarmason
2022-11-13 17:31                       ` René Scharfe
2022-11-04 13:22   ` [PATCH 10/13] bisect--helper: remove dead --bisect-{next-check,autostart} code Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 11/13] bisect--helper: convert to OPT_SUBCOMMAND_CB() Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 12/13] bisect--helper: make `state` optional Ævar Arnfjörð Bjarmason
2022-11-04 13:22   ` [PATCH 13/13] Turn `git bisect` into a full built-in Ævar Arnfjörð Bjarmason
2022-11-05  0:13   ` [PATCH 00/13] bisect: v2.30.0 "run" regressions + make it built-in Taylor Blau
2022-11-10 12:50   ` Johannes Schindelin

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