[RFC,PATCH] git-amend -- darcs like amend-record for git

From: Kirill Smelkov <kirr@mns.spb.ru>
Date: Feb 25, 2010, 14:16 UTC
Message-ID: <1267107365-2973-1-git-send-email-kirr@mns.spb.ru>

Ever wanted to type `git commit --amend HEAD~3` ? But had to fall back to commit and interactive rebase with fixup? And was tired by a lot of typing? And also rebase works only on clean worktree, so stash save and stash pop have to be used...

Forget it.

Now one can just do `git add ...` to prepare index, and then `git amend <commit>` to merge that changes from index into <commit>.

Yes, it uses rebase behind the scenes (or better sequencer, when it is available), but the end result is less typing and much better usability for humans. And it even tries to work in dirty worktree...

So operations like amending HEAD~3 take not significanltly more time, than just amending HEAD with already available `git commit --amend`.

It's only a prototype, without documentation and tests, just an RFC.

If you find the idea useful, please let me know. In case people want something like this, I'll try to polish it for inclusion into git.

Thanks,
Kirill
---
 contrib/git-amend.sh |   53 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 53 insertions(+), 0 deletions(-)
 create mode 100755 contrib/git-amend.sh

diff --git a/contrib/git-amend.sh b/contrib/git-amend.sh
new file mode 100755
index 0000000..1778594
--- /dev/null
+++ b/contrib/git-amend.sh
@@ -0,0 +1,53 @@
+#!/bin/sh -e
+# git-amend: darcs like amend-record for git
+# FIXME error handling
+
+USAGE="<commit>"
+. git-sh-setup
+
+test "$#" = 1 || usage
+
+commit=$1
+
+# let's see if $commit is a valid one, and also transform it to sha1 for it not
+# to be dependant on current HEAD
+commit=$(git rev-parse "$commit")
+
+# look out merges!
+test -z "$(git log --merges ${commit}~..HEAD)" || \
+	die "E: can't amend commits behind merges"
+
+# commit index, allowing empty commit just for being able to amend patch
+# description
+git commit --allow-empty -m "amend for $commit"
+
+# save worktree/index state
+work=$(git stash create)
+test -n "$work" && git update-ref HEAD.amend-backup $work
+
+# reset to clean work/index before going into rebase
+git reset --hard HEAD
+
+fixup_cmd=$(mktemp -t git-amend-fixupcmd.XXXXXX)
+rest_cmd=$(mktemp -t git-amend-restcmd.XXXXXX)
+trap 'rm -f "$fixup_cmd" "$rest_cmd"' 0
+{
+echo -ne "pick\t";  git log --pretty=oneline -1 ${commit}
+echo -ne "fixup\t"; git log --pretty=oneline -1 ${HEAD}
+} > "$fixup_cmd"
+
+git log --pretty=oneline --reverse ${commit}..HEAD~ | awk '{print "pick\t" $0;}' \
+	> "$rest_cmd"
+
+# now let's apply fixup part to commit
+GIT_EDITOR="cat $fixup_cmd >" git rebase -i ${commit}~
+
+# reword it
+git commit -v --amend
+
+# and apply rest
+GIT_EDITOR="cat $rest_cmd >" git rebase -i HEAD
+
+
+# restore worktree/index state
+test -n "$work" && git stash apply --index $work

-- 
1.7.0.91.g9803