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From: Jeff King <peff@peff.net>
To: "Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	sschuberth@gmail.com
Subject: Re: [PATCH] config: add conditional include
Date: Sun, 26 Jun 2016 14:27:16 -0400	[thread overview]
Message-ID: <20160626182715.GA12546@sigill.intra.peff.net> (raw)
In-Reply-To: <20160626070617.30211-1-pclouds@gmail.com>

On Sun, Jun 26, 2016 at 09:06:17AM +0200, Nguyễn Thái Ngọc Duy wrote:

> If the path argument in "include" starts with "gitdir:", it is
> followed by a wildmatch pattern. The include is only effective if
> $GIT_DIR matches the pattern. This is very useful to add configuration
> to a group of repositories.

I think this needs some more introduction to the concept. When you say
"path argument" here, I assumed you meant the value of include.path. But
you really mean: we are introducing a new concept for the "subsection"
field of include.*, which is to provide restrictions for conditional
includes.

It also may be worth discussing the motivation or examples.

> For convenience
> 
>  - "~" is expanded to $USER
> 
>  - if the pattern ends with '/', "**" will be appended (e.g. foo/
>    becomes foo/**). In other words, "foo/" automatically matches
>    everything in starting with "foo/".
> 
>  - if the pattern contains no slashes, it's wrapped around by "**/"
>    and "/**" (e.g. "foo" becomes "**/foo/**"). In other words, "foo"
>    matches any directory component in $GIT_DIR.
>
> The combination of the first two is used to group repositories by
> path. While the last one could be used to match worktree's basename.

This is a nice description, but it probably belongs in the
documentation.

I don't have any real opinion on the rules themselves, though they seem
reasonable to me (though in the first one I assume you mean $HOME).

> This code is originally written by Jeff King [1]. All genius designs
> are his. All bugs are mine (claiming bugs is just more fun :).

Heh. I have written this code in a "something like this" form at least 3
times over the years.  Conditional includes were always something I
planned into the original scheme, but had never actually found a good
use for it. ;)

> +	/*
> +	 * It's OK to run over cond_len in our checks here, as that just pushes
> +	 * us past the final ".", which cannot match any of our prefixes.
> +	 */
> +	if (skip_prefix(cond, "gitdir:", &value)) {

This would benefit from the skip_prefix_mem I proposed in:

  http://article.gmane.org/gmane.comp.version-control.git/298050

(and which is ae989a61dad98debe9899823ca987305f8e8020d in Junio's tree,
though it is only in pu so far, I think).

That eliminates the need for the comment, and auto-update cond_len, so
that later:

> +		strbuf_add(&pattern, value, cond_len - (value - cond));

...you do not have to do extra computation to get the correct length.

This is a tangent, but I wonder if expand_user_path() should take a
buf/len. It always puts the result into a new strbuf anyway, so it would
not be a big deal to do so. Skimming the output of grep, though, it
looks like this might be the only caller that would be helped.

> +		buf = expand_user_path(pattern.buf);
> +		if (buf) {
> +			strbuf_reset(&pattern);
> +			strbuf_addstr(&pattern, buf);
> +			free(buf);
> +		}

Maybe strbuf_attach() would be shorter here?

> +		} else if (!strchr(pattern.buf, '/')) {
> +			/* no slashes match one directory component */
> +			strbuf_insert(&pattern, 0, "**/", 3);
> +			strbuf_addstr(&pattern, "/**");
> +		}

I guess it's a little funny that "foo" and "foo/bar" are matched quite
differently. I wonder if a simpler rule would just be: relative paths
are unanchored.

-Peff

  reply	other threads:[~2016-06-26 18:28 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-26  7:06 [PATCH] config: add conditional include Nguyễn Thái Ngọc Duy
2016-06-26 18:27 ` Jeff King [this message]
2016-06-27 16:14   ` Duy Nguyen
2016-06-27 16:20     ` Jeff King
2016-06-27 16:32       ` Duy Nguyen
2016-06-27 16:35         ` Jeff King
2016-06-28 17:26 ` [PATCH v2 0/2] Config " Nguyễn Thái Ngọc Duy
2016-06-28 17:26   ` [PATCH v2 1/2] add skip_prefix_mem helper Nguyễn Thái Ngọc Duy
2016-06-28 17:26   ` [PATCH v2 2/2] config: add conditional include Nguyễn Thái Ngọc Duy
2016-06-28 20:49     ` Jeff King
2016-06-29  4:06       ` Duy Nguyen
2016-06-28 23:11     ` Eric Sunshine
2016-07-12 16:42     ` [PATCH v3] " Nguyễn Thái Ngọc Duy
2016-07-13  7:21       ` Matthieu Moy
2016-07-13  7:26         ` Jeff King
2016-07-13 12:48           ` Matthieu Moy
2016-07-13 15:57         ` Duy Nguyen
2016-07-14 15:33       ` [PATCH v4] " Nguyễn Thái Ngọc Duy
2016-07-14 15:53         ` Johannes Schindelin
2016-07-14 16:13           ` Duy Nguyen
2016-07-16 13:30             ` Johannes Schindelin
2016-07-16 14:48               ` Duy Nguyen
2016-07-16 15:08               ` Jeff King
2016-07-16 16:36                 ` Johannes Schindelin
2016-07-16 16:47                   ` Jeff King
2016-07-17  8:15                     ` Johannes Schindelin
2016-07-20 13:31                       ` Jeff King
2016-07-20 22:07                         ` Junio C Hamano
2016-07-20 16:39                     ` Jakub Narębski
2016-08-13  8:40         ` Duy Nguyen
2016-08-19 13:54           ` Jeff King
2016-08-20 21:08             ` Jakub Narębski
2016-08-22 12:43               ` Duy Nguyen
2016-08-22 12:59                 ` Matthieu Moy
2016-08-22 13:09                   ` Duy Nguyen
2016-08-22 13:22                     ` Matthieu Moy
2016-08-22 13:32                       ` Duy Nguyen
2016-08-23 13:42                         ` Johannes Schindelin
2016-08-24  9:37                           ` Duy Nguyen
2016-08-24 12:44                             ` Jakub Narębski
2016-08-24 14:17                               ` Jeff King
2016-06-28 20:28   ` [PATCH v2 0/2] Config " Jeff King
2016-06-28 20:51     ` Matthieu Moy
2016-06-28 21:03       ` Jeff King
2016-06-29  4:09     ` Duy Nguyen
2016-06-28 22:11   ` Junio C Hamano

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