Re: [PATCH v2] config: learn the "onbranch:" includeIf condition

From: Duy Nguyen <pclouds@gmail.com>
To: Denton Liu <liu.denton@gmail.com>
Cc: "Git Mailing List" <git@vger.kernel.org>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Johannes Schindelin" <Johannes.Schindelin@gmx.de>
Subject: Re: [PATCH v2] config: learn the "onbranch:" includeIf condition
Date: Wed, 5 Jun 2019 17:08:04 +0700	[thread overview]
Message-ID: <CACsJy8BaYhcnj_nofxmDB3txBCgSe0aDeR+LYPNqkHYg4OroHg@mail.gmail.com> (raw)
In-Reply-To: <3573995264441c50ea9529b3ee926d1ed3ec4ac8.1559330905.git.liu.denton@gmail.com>

On Sat, Jun 1, 2019 at 2:34 AM Denton Liu <liu.denton@gmail.com> wrote:
>
> Currently, if a user wishes to have individual settings per branch, they
> are required to manually keep track of the settings in their head and
> manually set the options on the command-line or change the config at
> each branch.
>
> Teach config the "onbranch:" includeIf condition so that it can
> conditionally include configuration files if the branch that is checked
> out in the current worktree matches the pattern given.

Just wondering, anybody wants special settings on detached head (and
if so, what syntax should it be)?

> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index 7e2a6f61f5..93aa4323c6 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -144,6 +144,13 @@ refer to linkgit:gitignore[5] for details. For convenience:
>         This is the same as `gitdir` except that matching is done
>         case-insensitively (e.g. on case-insensitive file sytems)
>
> +`onbranch`::
> +       The data that follows the keyword `onbranch:` is taken to be a pattern
> +       with standard globbing wildcards and two additional ones, `**/` and
> +       `/**`, that can match multiple path components. If we are in a worktree
> +       where the name of the branch that is currently checked out matches the
> +       pattern, the include condition is met.

Supporting transforming "foo/" to "foo/**" would be nice (gitdir and
gitdir/i do this). Useful when you organize your branches into
"subdirs".

> @@ -264,6 +265,24 @@ static int include_by_gitdir(const struct config_options *opts,
>         return ret;
>  }
>
> +static int include_by_branch(const char *cond, size_t cond_len)
> +{
> +       int flags;
> +       int ret;
> +       struct strbuf pattern = STRBUF_INIT;
> +       const char *refname = resolve_ref_unsafe("HEAD", 0, NULL, &flags);
> +       const char *shortname;
> +
> +       if (!refname || !(flags & REF_ISSYMREF) ||
> +                       !skip_prefix(refname, "refs/heads/", &shortname))

We probably don't even need to check more than !refname. Symbolic refs
from HEAD must be refs/heads/* or it's an error (fsck will complain).
But it's probably also ok to stay strict.

> +               return 0;
> +
> +       strbuf_add(&pattern, cond, cond_len);
> +       ret = !wildmatch(pattern.buf, shortname, WM_PATHNAME);
> +       strbuf_release(&pattern);
> +       return ret;
> +}
-- 
Duy