Re: [PATCH] git-add -p: be able to undo a given hunk

[Jeff King <peff@peff.net>]

On Mon, Jul 27, 2009 at 10:26:24AM +0200, Pierre Habouzit wrote:

> > No, I don't really think so in terms of implementation, but it is
> > really about a different mental model:
> > 
> >   1. You never delete things. You only copy or move them into registers.
> > 
> >   2. The interface should be the same whether you are moving between
> >      registers, or to/from the working tree.
> > 
> >   3. It extends naturally to multiple registers.
> 
> I like the general idea, I'm unsure what the UI for such tools would
> look like though.

I was thinking of unifying the multiple interfaces that we use to move
content and changes around into a single "git sort" and "git sort -i"
(and yes, I just made those names up, so feel free to call them crappy),
which would take a source and a destination (which would probably
default to the working tree and index respectively).

So you could do the equivalent of:

  - git add foo => git sort foo
  - git add -p => git sort -i foo
  - git checkout -- foo => git sort --from=index --to=tree foo
  - git checkout HEAD -- foo => git sort --from=HEAD --to=tree foo
  - git reset --mixed => git sort --from=HEAD --to=index
  - git reset --mixed foo => git sort --from=HEAD --to=index foo
    (note that this reset doesn't actually exist now, but is something
    that people try to do)
  - git stash save => git sort --to=%mystash
    (and note that I just made up some "this is a register" syntax;
     we maybe would really just want these as refs like refs/registers,
     so you would specify registers/mystash)
  - git stash -i => git sort --to=%mystash -i
    (interactive stash doesn't exist yet, of course)
  - git stash foo => git sort --to=%mystash foo
    (partial stash doesn't exist yet)
  - git diff HEAD stash -- foo | git apply => git sort --from=%mystash foo

So really, it could be a new way of interacting with the _regular_
index, as well, though perhaps it is overboard to completely redesign
the git interface. :) I just think it introduces a consistency to the
interface around the single concept of "moving your content around". So
in a sense it would be a good candidate for an alternative porcelain.
But do note that many common operations are more typing (like the
checkout replacements); that would be something to fix.

Again, just thinking out loud. Feel free to ignore, but if you think
there is anything interesting to pick out, let me know.

-Peff