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

Pierre Habouzit wrote:

One of my most frequent use case for git-add -p is when I had an intense
debug session with quite a lot of debug() traces added. I then want only
to select the hunks corresponding to the bugfixes and throw away the debug
ones.

With this new operation, instead of not staging hunks I don't want and
will eventually undo, I can just undo them.

This is what 'git checkout --interactive -- $file' or 'git reset
--interactive --hard' would accomplish, if they existed.  I wonder if
there would be a way to avoid yet more command letters, and instead
have "modes" that affect what happens with hunks you said 'y' to.  For
example:

  add -p		apply --cached
  undo -p		apply -R
  unstage -p		apply -R --cached
    [with hunks coming from diff --cached obviously]

(I picked 'undo' and 'unstage' semi-randomly, but it's not, after all,
an 'add' operation any more and the user doesn't need to know that the
program doing this is in fact git-add--interactive.)

+       u - do not stage this hunk and revert it

you're overloading terminology a bit too much for my taste.  It has
nothing to do with what git-revert does, and we shouldn't confuse
people more about that.

 Documentation/git-add.txt |    1 +
 git-add--interactive.perl |   38 ++++++++++++++++++++++++++++++--------

Tests?

Why not fold this into a single field?  It could, say, take values 0,
1, or '-R'.  It could probably be renamed to ACTION, but USE would be
fine if you want to avoid the code churn.  Then you shouldn't need
_completely_ separate handling during application.

+				$hunk[$ix]{UNDO} = 0;

and similarly for [yad] too, on the grounds that the user can go back
and change his choices with [KJ].  Of course that is not necessary if
you go the ACTION way outlined above.

+	if (@undo) {
+		my $fh;
+
+		open $fh, '| git apply -R';

This probably needs a --recount to cope with the case where the hunk
headers became stale/invalid through user [e]diting.

+		for (@{$head->{TEXT}}, @undo) {
+			print $fh $_;
+		}
+		if (!close $fh) {
+			for (@{$head->{TEXT}}, @undo) {
+				print STDERR $_;
+			}
+		}
+		refresh();
+	}

-- 
Thomas Rast
trast@{inf,student}.ethz.ch