From: Phillip Wood <phillip.wood123@gmail.com>
To: "Junio C Hamano" <gitster@pobox.com>, "René Scharfe" <l.s.r@web.de>
Cc: "Phillip Wood via GitGitGadget" <gitgitgadget@gmail.com>,
git@vger.kernel.org, "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
"Phillip Wood" <phillip.wood@dunelm.org.uk>
Subject: Re: [PATCH v2 08/11] rebase: remove redundant strbuf
Date: Tue, 14 Sep 2021 11:31:41 +0100 [thread overview]
Message-ID: <0c067b02-44e4-f719-42d9-7ceac5804e4a@gmail.com> (raw)
In-Reply-To: <xmqqczpccd57.fsf@gitster.g>
On 13/09/2021 23:40, Junio C Hamano wrote:
> René Scharfe <l.s.r@web.de> writes:
>
>> Am 13.09.21 um 17:19 schrieb Phillip Wood via GitGitGadget:
>>> From: Phillip Wood <phillip.wood@dunelm.org.uk>
>>>
>>> There is already an strbuf that can be reused for creating messages.
>>
>> Reminds me of a terrible joke from elementary school: In Peter's class
>> everybody is called Klaus, except Franz -- his name is Michael.
>>
>> Why would we want to use the same variable for multiple purposes? This
>> makes the code harder to read. And the allocation overhead for these
>> few cases should be negligible.
For better or worse reusing the same strbuf is a common pattern and when
I saw the code switch to using a different variable I wondered if it was
because the value of buf was being used later. It is also confusing to
free msg in a different place to all the other variables. rebase_cmd()
being so long does not help (msg is defined 763 lines before its first
use) as it makes it harder to see what is going on.
>> The most important question: Is this patch really needed to support
>> tags (the purpose of this series)?
>>
>>> msg is not freed if there is an error and there is a logic error where
>>> we call strbuf_release(&msg) followed by strbuf_reset(&msg) and
>>> strbuf_addf(&msg).
>>
>> strbuf_reset() after strbuf_release() is redundant but legal.
It is confusing to the reader though, I spent time checking why the
strbuf_release() call was there before concluding it was a mistake.
> All good points.
>
> I do not care too deeply either way, in the sense that it probably
> is better for this function to have two variables (with at least one
> of them having a meaningful name "msg" that tells readers what it is
> about), if the original submission to rewrite "rebase" in C used a
> single strbuf for both of these and given it a name (like "tmp")
> that makes it clear that the buffer is merely a temporary area
> without any longer term significance, I probably wouldn't have told
> the submitter to rewrite it to use separate strbuf variables.
>
> But if existing code already uses two variables, with at least one
> of them having a meaningful name that tells what it is used for, I
> see no reason why we want to rewrite it to use a single one.
In a short function where it is easy to see what happens between the
variable declaration and its use I'd agree but here everything is so
spread out I actually found the switch to a second variable confusing.
Best Wishes
Phillip
> Thanks.
>
next prev parent reply other threads:[~2021-09-14 10:31 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-08 9:49 [PATCH 00/11] rebase: dereference tags Phillip Wood via GitGitGadget
2021-09-08 9:49 ` [PATCH 01/11] t3407: run tests in $TEST_DIRECTORY Phillip Wood via GitGitGadget
2021-09-08 10:41 ` Ævar Arnfjörð Bjarmason
2021-09-08 9:49 ` [PATCH 02/11] t3407: use test_commit Phillip Wood via GitGitGadget
2021-09-08 10:39 ` Ævar Arnfjörð Bjarmason
2021-09-08 9:49 ` [PATCH 03/11] t3407: use test_cmp_rev Phillip Wood via GitGitGadget
2021-09-08 10:40 ` Ævar Arnfjörð Bjarmason
2021-09-08 13:42 ` Phillip Wood
2021-09-08 9:49 ` [PATCH 04/11] t3407: rename a variable Phillip Wood via GitGitGadget
2021-09-08 9:49 ` [PATCH 05/11] t3407: use test_path_is_missing Phillip Wood via GitGitGadget
2021-09-08 9:49 ` [PATCH 06/11] t3407: strengthen rebase --abort tests Phillip Wood via GitGitGadget
2021-09-08 10:42 ` Ævar Arnfjörð Bjarmason
2021-09-08 9:49 ` [PATCH 07/11] t3407: rework rebase --quit tests Phillip Wood via GitGitGadget
2021-09-08 9:49 ` [PATCH 08/11] rebase: remove redundant strbuf Phillip Wood via GitGitGadget
2021-09-09 10:35 ` Johannes Schindelin
2021-09-08 9:49 ` [PATCH 09/11] rebase: use our standard error return value Phillip Wood via GitGitGadget
2021-09-08 9:49 ` [PATCH 10/11] rebase: use lookup_commit_reference_by_name() Phillip Wood via GitGitGadget
2021-09-08 9:49 ` [PATCH 11/11] rebase: dereference tags Phillip Wood via GitGitGadget
2021-09-08 10:45 ` Ævar Arnfjörð Bjarmason
2021-09-13 15:19 ` [PATCH v2 00/11] " Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 01/11] t3407: run tests in $TEST_DIRECTORY Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 02/11] t3407: use test_commit Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 03/11] t3407: use test_cmp_rev Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 04/11] t3407: rename a variable Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 05/11] t3407: use test_path_is_missing Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 06/11] t3407: strengthen rebase --abort tests Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 07/11] t3407: rework rebase --quit tests Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 08/11] rebase: remove redundant strbuf Phillip Wood via GitGitGadget
2021-09-13 18:34 ` René Scharfe
2021-09-13 22:40 ` Junio C Hamano
2021-09-14 10:31 ` Phillip Wood [this message]
2021-09-14 10:33 ` Phillip Wood
2021-09-13 15:19 ` [PATCH v2 09/11] rebase: use our standard error return value Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 10/11] rebase: use lookup_commit_reference_by_name() Phillip Wood via GitGitGadget
2021-09-13 15:19 ` [PATCH v2 11/11] rebase: dereference tags Phillip Wood via GitGitGadget
2021-09-13 22:58 ` Junio C Hamano
2021-09-14 10:17 ` Phillip Wood
2021-09-14 13:27 ` Phillip Wood
2021-09-14 16:29 ` Junio C Hamano
2021-09-14 3:42 ` Elijah Newren
2021-09-14 9:48 ` Sergey Organov
2021-09-14 9:58 ` Phillip Wood
2021-09-14 4:02 ` [PATCH v2 00/11] " Elijah Newren
2021-09-21 10:23 ` [PATCH v3 00/10] " Phillip Wood via GitGitGadget
2021-09-21 10:23 ` [PATCH v3 01/10] t3407: run tests in $TEST_DIRECTORY Phillip Wood via GitGitGadget
2021-09-21 10:23 ` [PATCH v3 02/10] t3407: use test_commit Phillip Wood via GitGitGadget
2021-09-21 10:24 ` [PATCH v3 03/10] t3407: use test_cmp_rev Phillip Wood via GitGitGadget
2021-09-21 10:24 ` [PATCH v3 04/10] t3407: rename a variable Phillip Wood via GitGitGadget
2021-09-21 10:24 ` [PATCH v3 05/10] t3407: use test_path_is_missing Phillip Wood via GitGitGadget
2021-09-21 10:24 ` [PATCH v3 06/10] t3407: strengthen rebase --abort tests Phillip Wood via GitGitGadget
2021-09-21 10:24 ` [PATCH v3 07/10] t3407: rework rebase --quit tests Phillip Wood via GitGitGadget
2021-09-21 10:24 ` [PATCH v3 08/10] rebase: use our standard error return value Phillip Wood via GitGitGadget
2021-09-21 10:24 ` [PATCH v3 09/10] rebase: use lookup_commit_reference_by_name() Phillip Wood via GitGitGadget
2021-09-21 10:24 ` [PATCH v3 10/10] rebase: dereference tags Phillip Wood via GitGitGadget
2021-09-24 1:26 ` [PATCH v3 00/10] " Elijah Newren
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