Re: Questions about the new

From: David Kågedal <davidk@lysator.liu.se>
Date: Oct 12, 2009, 10:47 UTC
Message-ID: <871vl8ubw8.fsf@lysator.liu.se>
In-Reply-To: <loom.20091012T115746-719@post.gmane.org>

Sergio <sergio.callegari@gmail.com> writes:

Show 5 quoted lines

> Hi,
>
> I read from the release notes of git 1.6.5 about the new "replace" mechanism.
> It is presented as "a replacement of the "grafts" mechanism, with the added
> advantage that it can be transferred across repositories."

Grafts allow you to change a little part of commit objects (the parent relationship). Replacements allow (and require) you to change the whole commit object. So obviously, anything you can do with grafts can be done with replacements.

If you have your A-B-x-x-x history and want to remove A from the history, you replace B with a commit object that is identical, except for the missing parent link to A.

Replacements allow you do to other kinds of changes as well (comments, authorshiips) and changes to other object(?), so it is a much more general mechanism.

But I missed the discussion about it, so I'm not sure why it was felt it was needed, or why the grafts mechanism wasn't enough.

-- 
David Kågedal