Commit annotations (editable commit messages)

Commit annotations (editable commit messages)

[Vladimir Panteleev]

You have to agree, being able to edit commit messages in a controlled  
(logged/versioned) fashion is pretty useful. Aside mundane corrections  
such as typos or undocumented changes, it makes it possible to document  
bugs and other unintended changes in the commit that they were introduced.  
This is possible in centralized VCSes and is implemented in Subversion  
(controlled by a server-side hook).

When I presented somewhere the idea of migrating from SVN to Git, I got an  
opinion that the inability to edit commit messages (without rewriting  
history) would be a show-stopper, so I began to wonder how would it be  
possible to implement versioned editable commit messages (or commit  
"annotations") in Git:
1) the repository has a separate, special branch that only contains text  
files named by the SHA-1 of the commit they are describing
2) commit annotations are created/edited by creating/editing the  
respective text files, either manually or using some utilities (e.g. "git  
edit-annotation <SHA-1>" could check out the file from the branch, open up  
an editor and commit it back)
3) setting up "git push/pull" to also push/pull the annotations branch
4) "git log" and related commands would also show the contents of the  
respective text files, if they exist

The first three seem trivial... I'm not sure how to approach 4) though.  
Would it be possible to hack git to add a commit message output  
preprocessor hook OSLT?

There's also the problem with rebasing. Aside hacks with copies or  
symlinks in the annotations branch, what would be the best way to have an  
annotation follow commits after they're rebased (and have a different  
SHA-1)? Perhaps tie them to some property unique to the commit  
(timestamp?)? Depending on how this idea (and git rebase) is implemented,  
it could also just copy over the then-current version of the annotation  
into the new commit message when rebasing the commit.

-- 
Best regards,
  Vladimir                            mailto:thecybershadow@gmail.com

Re: Commit annotations (editable commit messages)

[Avery Pennarun]

2010/2/12 Vladimir Panteleev <thecybershadow@gmail.com>:
> You have to agree, being able to edit commit messages in a controlled
> (logged/versioned) fashion is pretty useful. Aside mundane corrections such
> as typos or undocumented changes, it makes it possible to document bugs and
> other unintended changes in the commit that they were introduced. This is
> possible in centralized VCSes and is implemented in Subversion (controlled
> by a server-side hook).

It sounds like you want to read about a new feature called git-notes:
http://www.kernel.org/pub/software/scm/git/docs/git-notes.html

Have fun,

Avery

Re: Commit annotations (editable commit messages)

[Vladimir Panteleev]

On Sat, 13 Feb 2010 00:55:46 +0200, Avery Pennarun <apenwarr@gmail.com>  
wrote:

> 2010/2/12 Vladimir Panteleev <thecybershadow@gmail.com>:
>> You have to agree, being able to edit commit messages in a controlled
>> (logged/versioned) fashion is pretty useful. Aside mundane corrections  
>> such
>> as typos or undocumented changes, it makes it possible to document bugs  
>> and
>> other unintended changes in the commit that they were introduced. This  
>> is
>> possible in centralized VCSes and is implemented in Subversion  
>> (controlled
>> by a server-side hook).
>
> It sounds like you want to read about a new feature called git-notes:
> http://www.kernel.org/pub/software/scm/git/docs/git-notes.html
>
> Have fun,
>
> Avery

Wow, thanks! Looks like I'm behind the times. (Currently stuck with  
msysGit/1.6.5)

The documentation looks pretty scant. Does anyone know how close were my  
suggestions to the actual implemented behavior (esp. regarding rebasing)?

-- 
Best regards,
  Vladimir                            mailto:thecybershadow@gmail.com

Re: Commit annotations (editable commit messages)

[Mark Lodato]

2010/2/12 Vladimir Panteleev <thecybershadow@gmail.com>:
>> It sounds like you want to read about a new feature called git-notes:
>> http://www.kernel.org/pub/software/scm/git/docs/git-notes.html
>
> Wow, thanks! Looks like I'm behind the times. (Currently stuck with
> msysGit/1.6.5)

Yes, what you described sounds *exactly* like git-notes :)

> The documentation looks pretty scant. Does anyone know how close were my
> suggestions to the actual implemented behavior (esp. regarding rebasing)?

1, 2, 3, and 4 are all implemented, as far as I know.  However, I
don't think notes copy during a rebase.  My gut feeling is that you
probably shouldn't be rebasing so much that this is an issue.  I'm
guessing that you should copy the note to the new commit ID after the
rebase.

I have also found the documentation lacking.  It helped a bit to see
the history.  It's pretty compact in the logs.  Here are two commands
to isolate the commits:

git log --reverse fed8a7de3592~..df27f6280545
gitk fed8a7de3592..df27f6280545

--
Mark

Re: Commit annotations (editable commit messages)

[Johan Herland]

On Saturday 13 February 2010, Mark Lodato wrote:
> 2010/2/12 Vladimir Panteleev <thecybershadow@gmail.com>:
> > The documentation looks pretty scant. Does anyone know how close were
> > my suggestions to the actual implemented behavior (esp. regarding
> > rebasing)?
> 
> 1, 2, 3, and 4 are all implemented, as far as I know.  However, I
> don't think notes copy during a rebase.

The last patch of the latest iteration of the jh/notes series (posted 5 
minutes ago) adds a "git notes copy" command that does just this. Patching 
rebase/cherry-pick/amend to call "git notes copy" should be fairly 
straightforward.


...Johan

-- 
Johan Herland, <johan@herland.net>
www.herland.net