Re: [RFC/PATCH] git put: an alternative to add/reset/checkout

...
But another way to think about it is that commits, the index, and the
working tree are all "locations" with content. And one common operation
you may want to do is to move content from one spot to another, either
whole, by file, or by diff hunks. To a new user, knowing that "add" is
the command for moving content from thet working tree to the index does
not help them know which command to use to do the opposite content
movement.
...
My idea is therefore to have a single command for moving content from
one location to another. You specify a source and a destination and get
a uniform interface for moving content.

A proof-of-concept patch is below. Be aware that is meant to be
illustrative and is not well tested. Also, it is a minimal presentation
of the concept. Other "locations" may also be meaningful. I'll include
some ideas below the patch.

---
 Makefile   |    1 +
 git-put.sh |   70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+), 0 deletions(-)
 create mode 100644 git-put.sh

diff --git a/Makefile b/Makefile
index e40ac0c..4564506 100644
--- a/Makefile
+++ b/Makefile

@@ -368,6 +368,7 @@ SCRIPT_SH += git-merge-one-file.sh

 SCRIPT_SH += git-merge-resolve.sh
 SCRIPT_SH += git-mergetool.sh
 SCRIPT_SH += git-pull.sh
+SCRIPT_SH += git-put.sh
 SCRIPT_SH += git-quiltimport.sh
 SCRIPT_SH += git-rebase.sh
 SCRIPT_SH += git-repack.sh

diff --git a/git-put.sh b/git-put.sh
new file mode 100644
index 0000000..f673e14
--- /dev/null
+++ b/git-put.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+
+SUBDIRECTORY_OK=Yes
+OPTIONS_KEEPDASHASH=Yes
+OPTIONS_SPEC="\
+git put [options] <from> <to> [--] <file...>
+
+Move contents from one place to another, where <from> and <to> are one of:
+  1. A commit (e.g., master, HEAD~10, v1.7.5)
+  2. The special token INDEX to indicate git's index.
+  3. The special token WORKTREE to indicate the working directory.
+
+Options:
+--
+p            don't move whole files; use the patch interface
+"
+. git-sh-setup
+
+patch=
+while test $# != 0; do
+       case "$1" in
+       -p) patch=--patch ;;
+       --) shift; break ;;
+       *) usage ;;
+       esac
+       shift
+done
+test $# -lt 2 && usage
+
+from=$1; shift
+to=$1; shift
+test "$1" = "--" && shift
+
+type_of() {
+       case "$1" in
+       INDEX) echo index ;;
+       WORKTREE) echo worktree ;;
+       *) echo commit ;;
+       esac
+}
+
+# Checkout contents to worktree without munging the index in
+# between.
+worktree_checkout() {
+       old=$GIT_INDEX_FILE
+       test -z "$old" && old=$(git rev-parse --git-dir)/index
+       new=$(git rev-parse --git-dir)/put-index.tmp
+       cp "$old" "$new" &&
+       GIT_INDEX_FILE=$new git checkout "$@"
+       status=$?
+       rm -f "$new"
+       exit $status
+}
+
+case "$(type_of "$from"),$(type_of "$to")" in
+*,commit)
+       die "You can't modify an existing commit." ;;
+index,index)
+       die "You can't move content from the index on top of itself." ;;
+worktree,index)
+       exec git add $patch -- "$@" ;;
+commit,index)
+       exec git reset $patch "$from" -- "$@" ;;
+index,worktree)
+       exec git checkout $patch -- "$@" ;;
+worktree,worktree)
+       die "You can't move content in the worktree on top of itself." ;;
+commit,worktree)
+       worktree_checkout $patch "$from" -- "$@" ;;
+esac

As you can see, this handles only three typoes of locations: the
worktree, the index, and an arbitrary commit (really a tree-ish).