Re: [RFC] undo and redo

[Carl Baldwin <cnb@fc.hp.com>]

On Wed, Aug 24, 2005 at 11:51:32AM -0700, Linus Torvalds wrote:
> 
> 
> On Wed, 24 Aug 2005, Carl Baldwin wrote:
> >
> > Oops.  I forgot to actually exit from the script if git-diff-files is
> > non-empty.
> > 
> > Also, looking at it now, I don't think keeping undo information in a
> > stack is the right thing.  But keeping more than just one would be good.
> > Oh well, my first shot is never perfect.  ;-)
> 
> I would actually argue that
> 
> 	git checkout -b newbranch <undo-point>
> 
> is the perfect undo.

Yes, this does the job nicely.  I've used it like this effectively.  I
meant for undo/redo to be a lighter weight way of moving (uncommitted)
changes out of the way briefly and then replaying them onto the working
directory later.

> It leaves the old state in the old branch, and creates a new branch (and
> checks it out) with the state you want to revert to. The advantage is
> exactly that there is no "stack" of undo's: you can have multiple
> independent undo's pending, and you can continue development at any of 
> them. And merge the results together.

The "stack" was the wrong thing to do.  I think I would have undo pick a
name like undo-1, undo-2 etc.  Or something like that.  redo would pick
the most recent unless told to do otherwise.

A possible advantage of undo is having the freedom to stay on the
current branch or switch to another.

> Of course, right now we don't have a "delete branch" command, but it's 
> really as simple as
>
> 	rm .git/refs/heads/branchname
> 
> (and eventually you may want to do a "git prune" to get rid of stale
> objects, but that's a separate issue).
> 
> 		Linus
> 

This brings up a good point (indirectly).  "git prune" would destroy the
undo objects.  I had thought of this but decided to ignore it for the
time being.

Carl

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 Carl Baldwin                        Systems VLSI Laboratory
 Hewlett Packard Company
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