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From: Glen Choo <chooglen@google.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH v3 2/4] remote: use remote_state parameter internally
Date: Tue, 26 Oct 2021 10:04:39 -0700	[thread overview]
Message-ID: <kl6l7ddz7m54.fsf@chooglen-macbookpro.roam.corp.google.com> (raw)
In-Reply-To: <xmqqbl3czik5.fsf@gitster.g>

Junio C Hamano <gitster@pobox.com> writes:

>> c) Replace the backpointer with a remote_state parameter. Expressive and
>>    fits the paradigm of "defaulting to the repo when needed", but
>>    interfaces are repetitive and shifts the responsibility of
>>    correctness to the caller (see v2).
> 
> ... if we want to support the what-if callers, I
> think the best approach would be a slight variant of c) above.
> 
> That is, pass branch and remote_state as two parameters, and when
> branch is not NULL, barf if it is not among remote_state.branches[],
> to protect against nonsense combinations.

Sounds reasonable to me. The resulting interface would look like the v2
one, but internally, this additional safety check will prevent misuse.

>>> a) Represent detached HEAD with a non-NULL "struct branch". This will
>>>    let us continue using the remote_state backpointer, which makes many
>>>    interfaces clean, but is somewhat invasive, error-prone and it uses
>>>    "struct branch" for something that is not a branch, which is itself
>>>    an error-prone interface.
>>
>> I'd rather not to go there.
>
> Actually, I take half of that back, as I think this would be the
> best direction in the longer term, and it conceptually is sound.
> After all, detached HEAD is not all that special--- when we ask for
> the "current branch" and the HEAD happens to be detached, we treat
> it as a perfectly valid state and behave as if we are on that
> unnamed branch.  The state probably deserves to be represented as a
> "struct branch" instance.
> [...] when things have stabilized, we should revisit
> and see if it is feasible to represent a detached HEAD state with an
> instance of "struct branch" and how simpler the interface would become
> when we did so.

This "longer term direction" sounds like what I envisioned with (e). I
agree that detached HEAD is a state that should be expressed with more
than just NULL, though I'm not sure that "struct branch" is the correct
abstraction. No point bikeshedding now of course, we'll cross that
bridge when we get there ;)

  reply	other threads:[~2021-10-26 17:04 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-07 19:07 [PATCH 0/2] remote: replace static variables with struct remote_state Glen Choo via GitGitGadget
2021-10-07 19:07 ` [PATCH 1/2] remote: move static variables into struct Glen Choo via GitGitGadget
2021-10-07 23:36   ` Junio C Hamano
2021-10-07 19:07 ` [PATCH 2/2] remote: add remote_state to struct repository Glen Choo via GitGitGadget
2021-10-07 23:39   ` Junio C Hamano
2021-10-08 17:30     ` Glen Choo
2021-10-13 19:31 ` [PATCH v2 0/3] remote: replace static variables with struct remote_state Glen Choo
2021-10-13 19:31   ` [PATCH v2 1/3] remote: move static variables into per-repository struct Glen Choo
2021-10-13 20:21     ` Junio C Hamano
2021-10-14 17:25       ` Glen Choo
2021-10-14 18:33         ` Junio C Hamano
2021-10-13 19:31   ` [PATCH v2 2/3] remote: use remote_state parameter internally Glen Choo
2021-10-13 20:23     ` Junio C Hamano
2021-10-13 19:31   ` [PATCH v2 3/3] remote: add struct repository parameter to external functions Glen Choo
2021-10-13 20:24     ` Junio C Hamano
2021-10-13 20:11   ` [PATCH v2 0/3] remote: replace static variables with struct remote_state Junio C Hamano
2021-10-13 20:27     ` Junio C Hamano
2021-10-13 22:00       ` Glen Choo
2021-10-13 21:56     ` Glen Choo
2021-10-13 23:37       ` Junio C Hamano
2021-10-14  1:25         ` Glen Choo
2021-10-19 22:43   ` [PATCH v3 0/4] " Glen Choo
2021-10-19 22:43     ` [PATCH v3 1/4] remote: move static variables into per-repository struct Glen Choo
2021-10-19 22:43     ` [PATCH v3 2/4] remote: use remote_state parameter internally Glen Choo
2021-10-20 19:45       ` Junio C Hamano
2021-10-20 20:31         ` Junio C Hamano
2021-10-20 22:08           ` Junio C Hamano
2021-10-25 18:09           ` Glen Choo
2021-10-25 19:36             ` Glen Choo
2021-10-25 20:33               ` Junio C Hamano
2021-10-25 23:00                 ` Glen Choo
2021-10-26  0:45                   ` Junio C Hamano
2021-10-26  1:22                     ` Junio C Hamano
2021-10-26 17:04                       ` Glen Choo [this message]
2021-10-27  2:28                         ` Junio C Hamano
2021-10-27 17:59                           ` Glen Choo
2021-10-27 20:03                             ` Junio C Hamano
2021-10-19 22:43     ` [PATCH v3 3/4] remote: remove the_repository->remote_state from static methods Glen Choo
2021-10-19 22:43     ` [PATCH v3 4/4] remote: add struct repository parameter to external functions Glen Choo
2021-10-28 18:30     ` [PATCH v4 0/6] remote: replace static variables with struct remote_state Glen Choo
2021-10-28 18:30       ` [PATCH v4 1/6] t5516: add test case for pushing remote refspecs Glen Choo
2021-10-28 20:17         ` Junio C Hamano
2021-11-15 18:42         ` Jonathan Tan
2021-11-15 20:09           ` Glen Choo
2021-10-28 18:30       ` [PATCH v4 2/6] remote: move static variables into per-repository struct Glen Choo
2021-10-28 18:30       ` [PATCH v4 3/6] remote: use remote_state parameter internally Glen Choo
2021-10-28 18:30       ` [PATCH v4 4/6] remote: remove the_repository->remote_state from static methods Glen Choo
2021-11-15 18:48         ` Jonathan Tan
2021-10-28 18:31       ` [PATCH v4 5/6] remote: die if branch is not found in repository Glen Choo
2021-11-15 18:50         ` Jonathan Tan
2021-11-15 20:06           ` Glen Choo
2021-11-16 17:45             ` Jonathan Tan
2021-10-28 18:31       ` [PATCH v4 6/6] remote: add struct repository parameter to external functions Glen Choo
2021-11-15 18:55         ` Jonathan Tan
2021-11-15 21:44           ` Glen Choo
2021-11-12  0:01       ` [PATCH v4 0/6] remote: replace static variables with struct remote_state Glen Choo

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