Re: New Proposal (simple) for Metadata in Git Commits: git-meta

From: Shawn O. Pearce <spearce@spearce.org>
Date: Dec 15, 2009, 22:05 UTC
Message-ID: <20091215220529.GD18319@spearce.org>
In-Reply-To: <93857A5A-744E-4A7C-B42D-23A56A48AAF7@lenary.co.uk>

Sam Elliott <sam@lenary.co.uk> wrote:

Show 5 quoted lines

> I had this idea a day or so again, and have written a simple  
> implementation to storing some semi-structured data in a git commit  
> message. This means that it's much easier for data to be found and  
> scraped from a certain commit, for instance what issue numbers commits  
> refer to or close.

So from your web page, this is basically just YAML shoved into the footer of the message:

--8<--
	Written half of the functionality. Namely the querying half.

	---git-meta---
	awesome: true
	Github:
	  user: lenary
	---git-meta---
-->8--

Why do we need the --git-meta-- delimiter lines?

JGit and Gerrit Code Review have already been following Git tradition by using footer messages as metadata. E.g. we have lines like:

--8<--
    init: Don't abort on empty directory
    
    The following sequence should work:
    
      mkdir testgit
      java -jar gerrit.war init -d testgit
    
    Since testgit is empty, it should be acceptable for us to populate the
    directory with our files.
    
    Bug: issue 358
    Change-Id: Ia85f31802066f8d39b042d3d057d33950a5035fd
    Signed-off-by: Shawn O. Pearce <sop@google.com>
-->8--

The JGit commit message parser has special logic to handle lines that smell like one of these tag lines. So long as there is no blank line in the footer paragraph, each of these tags can be read and processed. Continuation lines should start with whitespace.

I don't remember my YAML well enough, but isn't this existing standard still parseable by a YAML processor?

If you dropped the --git-meta-- tags above, JGit would happily recognize the awesome: and Github: tags, but it might need a bit more work to recognize the nested user: tag. Also, you'd be able to use git-meta on the git and Linux kernel repositories to pull out and work with Signed-off-by, Acked-by, etc.

-- 
Shawn.