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From: Junio C Hamano <gitster@pobox.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, Jeff King <peff@peff.net>,
	Taylor Blau <me@ttaylorr.com>, Elijah Newren <newren@gmail.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: Re: [PATCH 3/7] oid_object_info(): return "enum object_type"
Date: Mon, 08 Mar 2021 13:54:58 -0800	[thread overview]
Message-ID: <xmqqwnuh48gd.fsf@gitster.c.googlers.com> (raw)
In-Reply-To: <20210308200426.21824-4-avarab@gmail.com> ("Ævar Arnfjörð Bjarmason"'s message of "Mon, 8 Mar 2021 21:04:22 +0100")

Ævar Arnfjörð Bjarmason  <avarab@gmail.com> writes:

> Change oid_object_info() to return an "enum object_type", this is what
> it did anyway, except that it hardcoded -1 instead of an
> OBJ_BAD.
>
> Let's instead have it return the "enum object_type", at which point
> callers will expect OBJ_BAD. This allows for refactoring code that
> e.g. expected any "< 0" value, but would only have to deal with
> OBJ_BAD (= -1).

Hmph, I have a mixed feeling about this.

> diff --git a/builtin/cat-file.c b/builtin/cat-file.c
> index 5ebf13359e8..1d989c62a4e 100644
> --- a/builtin/cat-file.c
> +++ b/builtin/cat-file.c
> @@ -133,7 +133,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
>  
>  	case 'p':
>  		type = oid_object_info(the_repository, &oid, NULL);
> -		if (type < 0)
> +		if (type == OBJ_BAD)
>  			die("Not a valid object name %s", obj_name);

So, when oid_object_info() starts to return different negative value
to signal new kinds of errors, this codepath need to be changed, or
the control falls through to the rest of the case arm, which would
be worse than what the current code does (which is to die with less
specific error message).

> -		int type = oid_object_info(the_repository, &obj->oid, &size);
> -		if (type <= 0)
> +		enum object_type type = oid_object_info(the_repository, &obj->oid, &size);
> +		if (type == OBJ_BAD)
>  			die(_("did not receive expected object %s"),
>  			      oid_to_hex(&obj->oid));

Ditto.

And the issue is the same for all the other explicit comparison with
OBJ_BAD.  If we do it the other way around, i.e. leave these callers
as they are and add new negative return values to the function first,
and then convert "if negative, say error" to "if OBJ_BAD, say so,
else if we have this new type of error, say so", then the risk of
mistake becomes smaller.

But hopefully any such potential issue will be resolved by the end
of this short series, so as long as it won't be left as technical
debt, I am OK.

  reply	other threads:[~2021-03-08 21:55 UTC|newest]

Thread overview: 142+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-06-22  0:33 [PATCH 0/2] Pull objects of various types Daniel Barkalow
2005-06-22  0:35 ` [PATCH 1/2] Parse tags for absent objects Daniel Barkalow
2021-03-08 20:04   ` [PATCH 0/7] improve reporting of unexpected objects Ævar Arnfjörð Bjarmason
2021-03-28  2:13     ` [PATCH v2 00/10] " Ævar Arnfjörð Bjarmason
2021-03-28  2:13       ` [PATCH v2 01/10] object.c: stop supporting len == -1 in type_from_string_gently() Ævar Arnfjörð Bjarmason
2021-03-28  5:35         ` Junio C Hamano
2021-03-28 15:46           ` Ævar Arnfjörð Bjarmason
2021-03-28 18:25             ` Junio C Hamano
2021-04-22 18:09               ` Felipe Contreras
2021-03-28  2:13       ` [PATCH v2 02/10] object.c: refactor type_from_string_gently() Ævar Arnfjörð Bjarmason
2021-03-28  2:13       ` [PATCH v2 03/10] object.c: make type_from_string() return "enum object_type" Ævar Arnfjörð Bjarmason
2021-03-28  2:13       ` [PATCH v2 04/10] object-file.c: make oid_object_info() " Ævar Arnfjörð Bjarmason
2021-03-28  2:13       ` [PATCH v2 05/10] object-name.c: make dependency on object_type order more obvious Ævar Arnfjörð Bjarmason
2021-03-28  2:13       ` [PATCH v2 06/10] tree.c: fix misindentation in parse_tree_gently() Ævar Arnfjörð Bjarmason
2021-03-28  2:13       ` [PATCH v2 07/10] object.c: add a utility function for "expected type X, got Y" Ævar Arnfjörð Bjarmason
2021-03-28  2:13       ` [PATCH v2 08/10] object.c: add and use oid_is_type_or_die_msg() function Ævar Arnfjörð Bjarmason
2021-03-28  2:13       ` [PATCH v2 09/10] object tests: add test for unexpected objects in tags Ævar Arnfjörð Bjarmason
2021-03-28  2:13       ` [PATCH v2 10/10] tag: don't misreport type of tagged objects in errors Ævar Arnfjörð Bjarmason
2021-03-30  5:50         ` Junio C Hamano
2021-03-31 11:02           ` Jeff King
2021-03-31 18:05             ` Junio C Hamano
2021-03-31 18:31             ` Ævar Arnfjörð Bjarmason
2021-03-31 18:59               ` Jeff King
2021-03-31 20:46                 ` Ævar Arnfjörð Bjarmason
2021-04-01  7:54                   ` Jeff King
2021-04-01  8:32                     ` [PATCH] ref-filter: fix NULL check for parse object failure Jeff King
2021-04-01 13:56                       ` [PATCH v2 0/5] mktag tests & fix for-each-ref segfault Ævar Arnfjörð Bjarmason
2021-04-01 13:56                         ` [PATCH v2 1/5] mktag tests: parse out options in helper Ævar Arnfjörð Bjarmason
2021-04-01 13:56                         ` [PATCH v2 2/5] mktag tests: invert --no-strict test Ævar Arnfjörð Bjarmason
2021-04-01 13:56                         ` [PATCH v2 3/5] mktag tests: do fsck on failure Ævar Arnfjörð Bjarmason
2021-04-01 13:56                         ` [PATCH v2 4/5] mktag tests: test for maybe segfaulting for-each-ref Ævar Arnfjörð Bjarmason
2021-04-01 13:56                         ` [PATCH v2 5/5] ref-filter: fix NULL check for parse object failure Ævar Arnfjörð Bjarmason
2021-04-01 19:19                           ` Ramsay Jones
2021-04-01 19:56                         ` [PATCH v2 0/5] mktag tests & fix for-each-ref segfault Junio C Hamano
2021-04-02 11:37                           ` Ævar Arnfjörð Bjarmason
2021-04-02 20:51                             ` Junio C Hamano
2021-04-01 19:52                       ` [PATCH] ref-filter: fix NULL check for parse object failure Junio C Hamano
2021-03-31 18:41             ` [PATCH v2 10/10] tag: don't misreport type of tagged objects in errors Junio C Hamano
2021-03-31 19:00               ` Jeff King
2021-03-28  9:27       ` [PATCH v2 00/10] improve reporting of unexpected objects Jeff King
2021-03-29 13:34         ` Ævar Arnfjörð Bjarmason
2021-03-31 10:43           ` Jeff King
2021-04-09  8:07       ` [PATCH 0/2] blob/object.c: trivial readability improvements Ævar Arnfjörð Bjarmason
2021-04-09  8:07         ` [PATCH 1/2] blob.c: remove buffer & size arguments to parse_blob_buffer() Ævar Arnfjörð Bjarmason
2021-04-09 17:51           ` Jeff King
2021-04-09 22:31             ` Junio C Hamano
2021-04-10 12:57             ` Ævar Arnfjörð Bjarmason
2021-04-10 13:01               ` Ævar Arnfjörð Bjarmason
2021-04-13  8:25               ` Jeff King
2021-04-09  8:07         ` [PATCH 2/2] object.c: initialize automatic variable in lookup_object() Ævar Arnfjörð Bjarmason
2021-04-09 17:53           ` Jeff King
2021-04-09 22:32             ` Junio C Hamano
2021-04-09  8:32         ` [PATCH 0/6] {tag,object}*.c: refactorings + prep for a larger change Ævar Arnfjörð Bjarmason
2021-04-09  8:32           ` [PATCH 1/6] object.c: stop supporting len == -1 in type_from_string_gently() Ævar Arnfjörð Bjarmason
2021-04-09 18:06             ` Jeff King
2021-04-09 18:10               ` Jeff King
2021-04-09  8:32           ` [PATCH 2/6] object.c: remove "gently" argument to type_from_string_gently() Ævar Arnfjörð Bjarmason
2021-04-09 18:10             ` Jeff King
2021-04-09  8:32           ` [PATCH 3/6] object.c: make type_from_string() return "enum object_type" Ævar Arnfjörð Bjarmason
2021-04-09 18:14             ` Jeff King
2021-04-09 19:42               ` Ævar Arnfjörð Bjarmason
2021-04-09 21:29                 ` Jeff King
2021-04-09  8:32           ` [PATCH 4/6] object-file.c: make oid_object_info() " Ævar Arnfjörð Bjarmason
2021-04-09 18:24             ` Jeff King
2021-04-09  8:32           ` [PATCH 5/6] object-name.c: make dependency on object_type order more obvious Ævar Arnfjörð Bjarmason
2021-04-09 18:36             ` Jeff King
2021-04-09  8:32           ` [PATCH 6/6] tag.c: use type_from_string_gently() when parsing tags Ævar Arnfjörð Bjarmason
2021-04-09 18:42             ` Jeff King
2021-04-09  8:49           ` [PATCH 0/7] object.c: add and use "is expected" utility function + object_as_type() use Ævar Arnfjörð Bjarmason
2021-04-09  8:49             ` [PATCH 1/7] tree.c: fix misindentation in parse_tree_gently() Ævar Arnfjörð Bjarmason
2021-04-09  8:49             ` [PATCH 2/7] object.c: add a utility function for "expected type X, got Y" Ævar Arnfjörð Bjarmason
2021-04-09  8:49             ` [PATCH 3/7] object.c: add and use oid_is_type_or_die_msg() function Ævar Arnfjörð Bjarmason
2021-04-09  8:49             ` [PATCH 4/7] commit-graph: use obj->type, not object_as_type() Ævar Arnfjörð Bjarmason
2021-04-09  8:50             ` [PATCH 5/7] commit.c: don't use deref_tag() -> object_as_type() Ævar Arnfjörð Bjarmason
2021-04-09  8:50             ` [PATCH 6/7] object.c: normalize brace style in object_as_type() Ævar Arnfjörð Bjarmason
2021-04-09  8:50             ` [PATCH 7/7] object.c: remove "quiet" parameter from object_as_type() Ævar Arnfjörð Bjarmason
2021-04-20 13:36             ` [PATCH v2 0/8] object.c: add and use "is expected" utility function + object_as_type() use Ævar Arnfjörð Bjarmason
2021-04-20 13:36               ` [PATCH v2 1/8] tree.c: fix misindentation in parse_tree_gently() Ævar Arnfjörð Bjarmason
2021-04-20 13:36               ` [PATCH v2 2/8] object.c: add a utility function for "expected type X, got Y" Ævar Arnfjörð Bjarmason
2021-04-21 22:02                 ` Jonathan Tan
2021-04-22  6:10                   ` Ævar Arnfjörð Bjarmason
2021-04-20 13:36               ` [PATCH v2 3/8] object.c: add and use oid_is_type_or_die_msg() function Ævar Arnfjörð Bjarmason
2021-04-21 22:07                 ` Jonathan Tan
2021-04-21 23:28                 ` Josh Steadmon
2021-04-28  4:12                   ` Junio C Hamano
2021-04-20 13:36               ` [PATCH v2 4/8] commit-graph: use obj->type, not object_as_type() Ævar Arnfjörð Bjarmason
2021-04-20 13:36               ` [PATCH v2 5/8] branch tests: assert lookup_commit_reference_gently() error Ævar Arnfjörð Bjarmason
2021-04-20 13:36               ` [PATCH v2 6/8] commit.c: don't use deref_tag() -> object_as_type() Ævar Arnfjörð Bjarmason
2021-04-21 22:26                 ` Jonathan Tan
2021-04-20 13:36               ` [PATCH v2 7/8] object.c: normalize brace style in object_as_type() Ævar Arnfjörð Bjarmason
2021-04-20 13:37               ` [PATCH v2 8/8] object.c: remove "quiet" parameter from object_as_type() Ævar Arnfjörð Bjarmason
2021-04-20 13:00           ` [PATCH v2 00/10] {tag,object}*.c: refactorings + prep for a larger change Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 01/10] object.c: stop supporting len == -1 in type_from_string_gently() Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 02/10] object.c: remove "gently" argument to type_from_string_gently() Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 03/10] object.c: make type_from_string() return "enum object_type" Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 04/10] object-file.c: make oid_object_info() " Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 05/10] object-name.c: make dependency on object_type order more obvious Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 06/10] tag.c: use type_from_string_gently() when parsing tags Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 07/10] hash-object: pass along type length to object.c Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 08/10] hash-object: refactor nested else/if/if into else if/else if Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 09/10] hash-object: show usage on invalid --type Ævar Arnfjörð Bjarmason
2021-04-20 13:00             ` [PATCH v2 10/10] object.c: move type_from_string() code to its last user Ævar Arnfjörð Bjarmason
2021-04-20 12:50         ` [PATCH v2 00/10] object.c et al: tests, small bug fixes etc Ævar Arnfjörð Bjarmason
2021-04-20 12:50           ` [PATCH v2 01/10] cat-file tests: test for bogus type name handling Ævar Arnfjörð Bjarmason
2021-04-29  4:15             ` Junio C Hamano
2021-04-20 12:50           ` [PATCH v2 02/10] hash-object tests: more detailed test for invalid type Ævar Arnfjörð Bjarmason
2021-04-20 12:50           ` [PATCH v2 03/10] mktree tests: add test for invalid object type Ævar Arnfjörð Bjarmason
2021-04-20 12:50           ` [PATCH v2 04/10] object-file.c: take type id, not string, in read_object_with_reference() Ævar Arnfjörð Bjarmason
2021-04-29  4:37             ` Junio C Hamano
2021-04-20 12:50           ` [PATCH v2 05/10] {commit,tree,blob,tag}.c: add a create_{commit,tree,blob,tag}() Ævar Arnfjörð Bjarmason
2021-04-29  4:45             ` Junio C Hamano
2021-04-29 12:01               ` Ævar Arnfjörð Bjarmason
2021-04-20 12:50           ` [PATCH v2 06/10] blob.c: remove parse_blob_buffer() Ævar Arnfjörð Bjarmason
2021-04-29  4:51             ` Junio C Hamano
2021-04-20 12:50           ` [PATCH v2 07/10] object.c: simplify return semantic of parse_object_buffer() Ævar Arnfjörð Bjarmason
2021-04-20 12:50           ` [PATCH v2 08/10] object.c: don't go past "len" under die() in type_from_string_gently() Ævar Arnfjörð Bjarmason
2021-04-29  4:55             ` Junio C Hamano
2021-04-20 12:50           ` [PATCH v2 09/10] mktree: stop setting *ntr++ to NIL Ævar Arnfjörð Bjarmason
2021-04-29  5:01             ` Junio C Hamano
2021-04-20 12:50           ` [PATCH v2 10/10] mktree: emit a more detailed error when the <type> is invalid Ævar Arnfjörð Bjarmason
2021-03-08 20:04   ` [PATCH 1/7] object.c: refactor type_from_string_gently() Ævar Arnfjörð Bjarmason
2021-03-08 20:52     ` Taylor Blau
2021-03-09 10:46     ` Jeff King
2021-03-08 20:04   ` [PATCH 2/7] object.c: make type_from_string() return "enum object_type" Ævar Arnfjörð Bjarmason
2021-03-08 20:56     ` Taylor Blau
2021-03-08 21:48     ` Junio C Hamano
2021-03-08 20:04   ` [PATCH 3/7] oid_object_info(): " Ævar Arnfjörð Bjarmason
2021-03-08 21:54     ` Junio C Hamano [this message]
2021-03-08 22:32       ` Junio C Hamano
2021-03-09 10:34     ` Jeff King
2021-03-08 20:04   ` [PATCH 4/7] tree.c: fix misindentation in parse_tree_gently() Ævar Arnfjörð Bjarmason
2021-03-08 20:04   ` [PATCH 5/7] object.c: add a utility function for "expected type X, got Y" Ævar Arnfjörð Bjarmason
2021-03-08 20:59     ` Taylor Blau
2021-03-08 22:15     ` Junio C Hamano
2021-03-08 20:04   ` [PATCH 6/7] object tests: add test for unexpected objects in tags Ævar Arnfjörð Bjarmason
2021-03-09 10:44     ` Jeff King
2021-03-28  1:35       ` Ævar Arnfjörð Bjarmason
2021-03-28  9:06         ` Jeff King
2021-03-28 15:39           ` Ævar Arnfjörð Bjarmason
2021-03-29  9:16             ` Jeff King
2021-03-08 20:04   ` [PATCH 7/7] tag: don't misreport type of tagged objects in errors Ævar Arnfjörð Bjarmason
2005-06-22  0:35 ` [PATCH 2/2] Pull misc objects Daniel Barkalow

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