Re: [PATCH] log: add log.excludeDecoration config option

> Hi Stolee,
> 
> On Mon, Apr 13, 2020 at 03:28:39PM +0000, Derrick Stolee via GitGitGadget wrote:
>> From: Derrick Stolee <dstolee@microsoft.com>
>>
>> In 'git log', the --decorate-refs-exclude option appends a pattern
>> to a string_list. This list is used to prevent showing some refs
>> in the decoration output, or even by --simplify-by-decoration.
>>
>> Users may want to use their refs space to store utility refs that
>> should not appear in the decoration output. For example, Scalar [1]
>> runs a background fetch but places the "new" refs inside the
>> refs/scalar/hidden/<remote>/* refspace instead of refs/<remote>/*
>> to avoid updating remote refs when the user is not looking. However,
>> these "hidden" refs appear during regular 'git log' queries.
>>
>> A similar idea to use "hidden" refs is under consideration for core
>> Git [2].
>>
>> Add the 'log.excludeDecoration' config option so users can exclude
>> some refs from decorations by default instead of needing to use
>> --decorate-refs-exclude manually. The config value is multi-valued
>> much like the command-line option.
>>
>> There are several tests in t4202-log.sh that test the
>> --decorate-refs-(include|exclude) options, so these are extended.
>> Since the expected output is already stored as a file, simply add
>> new calls that replace a "--decorate-refs-exclude" option with an
>> in-line config setting.
>>
>> [1] https://github.com/microsoft/scalar
>> [2] https://lore.kernel.org/git/77b1da5d3063a2404cd750adfe3bb8be9b6c497d.1585946894.git.gitgitgadget@gmail.com/
>>
>> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
>> ---
>>     log: add log.excludeDecoration config option
>>
>>     This was something hinted at in the "fetch" step of the background
>>     maintenance RFC. Should be a relatively minor addition to our config
>>     options.
>>
>>     We definitely want this feature for microsoft/git (we would set
>>     log.excludeDecoration=refs/scalar/* in all Scalar repos), but we will
>>     wait for feedback from the community.
>>
>>     Thanks, -Stolee
>>
>> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-610%2Fderrickstolee%2Flog-exclude-decoration-v1
>> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-610/derrickstolee/log-exclude-decoration-v1
>> Pull-Request: https://github.com/gitgitgadget/git/pull/610
>>
>>  Documentation/config/log.txt |  5 +++++
>>  builtin/log.c                | 14 ++++++++++++++
>>  t/t4202-log.sh               | 22 ++++++++++++++++++++++
>>  3 files changed, 41 insertions(+)
>>
>> diff --git a/Documentation/config/log.txt b/Documentation/config/log.txt
>> index e9e1e397f3f..1a158324f79 100644
>> --- a/Documentation/config/log.txt
>> +++ b/Documentation/config/log.txt
>> @@ -18,6 +18,11 @@ log.decorate::
>>  	names are shown. This is the same as the `--decorate` option
>>  	of the `git log`.
>>
>> +log.excludeDecoration::
>> +	Exclude the specified patterns from the log decorations. This multi-
>> +	valued config option is the same as the `--decorate-refs-exclude`
>> +	option of `git log`.
>> +
> 
> Thanks for this documentation update. Do you think that it would be
> worth updating the entry for '--decorate-refs-exclude', too? I figure
> that it would be good, since scripters who look at 'git log's man page
> before 'git config's would have a trail to follow in case they want a
> persistent '--decorate-refs-exclude' option.

>>  log.follow::
>>  	If `true`, `git log` will act as if the `--follow` option was used when
>>  	a single <path> is given.  This has the same limitations as `--follow`,
>> diff --git a/builtin/log.c b/builtin/log.c
>> index 83a4a6188e2..d7d1d5b7143 100644
>> --- a/builtin/log.c
>> +++ b/builtin/log.c
>> @@ -236,7 +236,21 @@ static void cmd_log_init_finish(int argc, const char **argv, const char *prefix,
>>  	}
>>
>>  	if (decoration_style) {
>> +		const struct string_list *config_exclude =
>> +			repo_config_get_value_multi(the_repository,
>> +						    "log.excludeDecoration");
>> +
>> +		if (config_exclude) {
>> +			struct string_list_item *item;
>> +			for (item = config_exclude->items;
>> +			     item && item < config_exclude->items + config_exclude->nr;
>> +			     item++)
> 
> Any reason not to use the 'for_each_string_list_item' macro in
> 'string-list.h' for this?