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From: Matthieu Moy <Matthieu.Moy@grenoble-inp•fr>
To: Junio C Hamano <gitster@pobox•com>
Cc: "Štěpán Němec" <stepnem@gmail•com>,
	git@vger•kernel.org, "Petr Onderka" <gsvick@gmail•com>
Subject: Re: [PATCH v3?] Add global and system-wide gitattributes
Date: Tue, 31 Aug 2010 00:55:53 +0200	[thread overview]
Message-ID: <vpqhbibbthi.fsf@bauges.imag.fr> (raw)
In-Reply-To: <7vbp8jerfq.fsf@alter.siamese.dyndns.org> (Junio C. Hamano's message of "Mon\, 30 Aug 2010 14\:11\:53 -0700")

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

> Junio C Hamano <gitster@pobox•com> writes:
>
>> Matthieu Moy <Matthieu.Moy@grenoble-inp•fr> writes:
>>
>>> I don't understand why this breaks the test. It seems blame
>>> --encoding=UTF-8 relies on the fact that the i18n section of the
>>> configuration is not loaded.
>>
>> That's interesting; I haven't traced the codepath involved, but I do not
>> think "configuration is not loaded" is the issue. "Reading either before
>> the main codepath is ready, or more likely overwriting/destroying what the
>> main codepath has read it by re-reading the configuration" may be.
>
> I think that hunch is correct.

Confirmed.

> A typical way we default to hardcoded value, overridable by
> configuration file, and then further use command line to override
> that, is for the main codepath to do the following in this order:
>
>  - call git_config(git_appropriate_config); this changes the variables
>    (with possibly hardcoded default) defined in environment.c;
>
>  - parse command line options and override the variable;
>
>  - use the variable at runtime.

Yes, this is the problem, with git_log_output_encoding as you guessed.

> The correct solution would be twofold, but the latter is rather painful:

Not that much in the case of git_log_output_encoding, but other uses
of the same pattern may exist.

>  - The call from the bootstrap_attr_stack should use a callback that reads
>    only the attribute file location configuration and _nothing else_.
[...]
>  - The way programs (this is not limited to blame and other rev-list
>    machinery users) implement the "use configured values but let command
>    line override them" need to be changed.

I think it's reasonable to do both. Having both git_config() and
command-line parsing write to the same variable is fragile and should
be avoided IMHO, but OTOH, arbitrary calls to
git_config(git_default_config) may break other things, so ...

>    One possibility is to copy the values determined by reading the config
>    and the command line to their own variables, so that later random call
>    to git_config() won't stomp on the actual values to be used.  This is
>    painful as environment.c variables are _meant_ to be easily usable as
>    global variables and copying them away (which means they now need to be
>    passed around throughout the callchain in the various APIs) defeats
>    the whole point of having them.

I just keep two global variables instead of two, and implement a
straightforward accessor. Command-line option parsing already used to
write to a global variable, so it doesn't change much.

New patch serie follows,

-- 
Matthieu Moy
http://www-verimag.imag.fr/~moy/

  reply	other threads:[~2010-08-30 22:56 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-11  1:04 [PATCH/RFC] Add global and system-wide gitattributes Petr Onderka
2010-08-11  9:20 ` Henrik Grubbström
2010-08-11 10:50   ` Petr Onderka
2010-08-11 12:31 ` Matthieu Moy
2010-08-11 22:19 ` Junio C Hamano
2010-08-16 16:51   ` Petr Onderka
2010-08-16 16:56     ` [PATCH v2] " Petr Onderka
2010-08-25  9:55       ` Štěpán Němec
2010-08-28 17:33         ` Matthieu Moy
2010-08-30  5:34           ` Junio C Hamano
2010-08-30  9:09             ` Štěpán Němec
2010-08-28 18:35       ` Matthieu Moy
2010-08-28 18:41         ` [PATCH] core.attributesfile: a fix, a simplification, and a test Matthieu Moy
2010-08-29 10:32           ` [PATCH v3?] Add global and system-wide gitattributes Štěpán Němec
2010-08-30  8:04             ` Junio C Hamano
2010-08-30  8:26               ` Matthieu Moy
2010-08-30 20:47                 ` Junio C Hamano
2010-08-30 21:11                   ` Junio C Hamano
2010-08-30 22:55                     ` Matthieu Moy [this message]
2010-08-30 23:15                       ` [PATCH 1/3 v2] tests: factor HOME=$(pwd) in test-lib.sh Matthieu Moy
2010-08-31  7:42                         ` Ævar Arnfjörð Bjarmason
2010-09-01  7:56                           ` Ævar Arnfjörð Bjarmason
2010-09-01 15:24                             ` Junio C Hamano
2010-09-01 15:40                               ` Ævar Arnfjörð Bjarmason
2010-09-01 16:57                                 ` Matthieu Moy
2010-08-30 23:15                       ` [PATCH 2/3] don't write to git_log_output_encoding outside git_config() Matthieu Moy
2010-09-02  8:56                         ` Matthieu Moy
2010-09-02 15:49                           ` Junio C Hamano
2010-08-30 23:15                       ` [PATCH 3/3 v4] Add global and system-wide gitattributes Matthieu Moy
2010-08-31 22:41                         ` Matthieu Moy
2010-08-31 22:42                           ` [PATCH] " Matthieu Moy
2010-08-31 23:56                           ` [PATCH 3/3 v4] " Junio C Hamano
2010-08-30  9:50               ` [PATCH] tests: factor HOME=$(pwd) in test-lib.sh Matthieu Moy
2010-08-30 10:22                 ` Ævar Arnfjörð Bjarmason
2010-08-30 10:54                   ` Matthieu Moy
2010-08-30 11:08                     ` Ævar Arnfjörð Bjarmason

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