On Sat, 13 Aug 2005, Linus Torvalds wrote:

> That's correct. Same things apply: you can move a patch over, and create a 
> new one with a modified comment, but basically the _old_ commit will be 
> immutable.

Let me clarify.

You can entirely _drop_ old branches, so commits may be immutable, but
nothing forces you to keep them. Of course, when you drop a commit, you'll 
always end up dropping all the commits that depended on it, and if you 
actually got somebody else to pull that commit you can't drop it from 
_their_ repository, but undoing things is not impossible.

For example, let's say that you've made a mess of things: you've committed
three commits "old->a->b->c", and you notice that "a" was broken, but you
want to save "b" and "c". What you can do is

        # Create a branch "broken" that is the current code
        # for reference
        git branch broken

        # Reset the main branch to three parents back: this 
        # effectively undoes the three top commits
        git reset HEAD^^^
        git checkout -f

        # Check the result visually to make sure you know what's
        # going on
        gitk --all

        # Re-apply the two top ones from "broken"
        # First "parent of broken" (aka b):
        git-diff-tree -p broken^ | git-apply --index
        git commit --reedit=broken^

        # Then "top of broken" (aka c):
        git-diff-tree -p broken | git-apply --index
        git commit --reedit=broken

and you've now re-applied (and possibly edited the comments) the two
commits b/c, and commit "a" is basically gone (it still exists in the
"broken" branch, of course).

Finally, check out the end result again:

        # Look at the new commit history
        gitk --all

to see that everything looks sensible.

And then, you can just remove the broken branch if you decide you really 
don't want it:

        # remove 'broken' branch
        rm .git/refs/heads/broken

        # Prune old objects if you're really really sure
        git prune

And yeah, I'm sure there are other ways of doing this. And as usual, the 
above is totally untested, and I just wrote it down in this email, so if 
I've done something wrong, you'll have to figure it out on your own ;)

To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to