Re: [PATCH v4 1/2] for-each-repo: new command used for multi-repo operations

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Jan 28, 2013, 08:10 UTC
Message-ID: <20130128081006.GA2434@elie.Belkin>
In-Reply-To: <CAFXTnz6GTVgY4DK-FLELGF-Cb1=iNYyWcUsUiaUytGRx9Tr4Ow@mail.gmail.com>

Hi,

Lars Hjemli wrote:

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> [1] The 'git -a' rewrite patch shows how I think about this command -
> it's just an option to the 'git' command, modifying the way any
> subcommand is invoked (btw: I don't expect that patch to be applied
> since 'git-all' was deemed to generic, so I'll just carry the patch in
> my own tree).

As one data point, 'git all' also seems too generic to me but 'git -a' doesn't. Intuition can be weird.

So if I ran the world, then having commands

	git -a diff

and

	git for-each-repo git diff

do the same thing would be fine.  Of course I don't run the world. ;-)

[...]

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>> One more thing that nobody brought up during the previous reviews is
>> if we want to support subset of repositories by allowing the
>> standard pathspec match mechanism.  For example,
>>
>>         git for-each-repo -d git diff --name-only -- foo/ bar/b\*z
>>
>> might be a way to ask "please find repositories match the given
>> pathspecs (i.e. foo/ bar/b\*z) and run the command in the ones that
>> are dirty".  We would need to think about how to mark the end of the
>> command though---we could borrow \; from find(1), even though find
>> is not the best example of the UI design.

In most non-git commands, "--" represents an end-of-options marker, allowing arbitrary options afterward without having to worry about escaping minus signs. So in that spirit, if this weren't a git command, I'd expect to be able to do

	for-each-repo -- git diff -- '*.c'

and have the second '--' passed verbatim to "git diff".

Unfortunately in git (imitating commands like "grep", I suppose), "--" means "paths start here". That means that with the git convention, there is only one place to pass paths to a given command.

Tracing backwards: it would be really nice to be able to do

	git for-each-repo git grep -e foo -- '*.c'

or

	git -a grep -e foo -- '*.c'

For this practical reason, it seems that paths listed after the '--' should go to the command being run. On the other hand, if I wanted to limit my for-each-repo run to repositories in two subdirectories of the cwd, I'd be tempted to try

	git for-each-repo git grep -e foo -- src/ doc/

And if I wanted to limit to different file types in the repositories under each directory, it would be tempting to use

	git for-each-repo git grep -e foo -- 'src/*.c' 'doc/*.txt'

Is there a convention that would be usable today that is roughly forward-compatible with that? (To throw an example out, requiring that each pathspec passed to for-each-repo either starts with '*' or contains no wildcards.)

Thanks, Jonathan