Re: [PATCH] update-index: add --swap to swap index and worktree content

[Michael J Gruber <git@drmicha.warpmail.net>]

Nguyễn Thái Ngọc Duy venit, vidit, dixit 12.08.2011 16:07:
> Sometimes "git add -p" with "e" to edit the patch does not satisfy me.
> What I want is a quick way to modify index content without changing
> worktree, then I can continue adding more hunks to the index.
> 
> With this option, I can swap index out for a quick edit, then swap it in
> again.

I had to think about that explanation for a while (partly because "git
add" does not alter the wt either). So, your patch would support the
following workflow:

git add foo # have index == wt
hack foo # change foo in wt
git update-index --swap foo # add foo and reset to previous state

Am I understanding you right? The option could trickle down to "add".

I share the pov that "add -p with e" sometimes doesn't cut it. But
similarly, the fact that "add -p" can't be used to undo a previous "add
-p" is suboptimal. Both issues could be solved with a 3way stage tool. I
have this on my todo/wish list, and I seem to recall that Jeff or Junio
came up with a few lines of (scripting) code for that. That would depend
on the availability of proper tools, though (e.g. vim in diff mode).

--swap might be useful nevertheless.

> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  Not sure if anybody has the same needs, enough to polish it and make
>  it to master.
> 
>  builtin/update-index.c |   16 ++++++++++++++++
>  1 files changed, 16 insertions(+), 0 deletions(-)
> 
> diff --git a/builtin/update-index.c b/builtin/update-index.c
> index a6a23fa..b96065a 100644
> --- a/builtin/update-index.c
> +++ b/builtin/update-index.c
> @@ -22,6 +22,7 @@
>  static int allow_add;
>  static int allow_remove;
>  static int allow_replace;
> +static int swap_entry;
>  static int info_only;
>  static int force_remove;
>  static int verbose;
> @@ -104,6 +105,19 @@ static int add_one_path(struct cache_entry *old, const char *path, int len, stru
>  		free(ce);
>  		return -1;
>  	}
> +	if (swap_entry) {
> +		struct checkout state;
> +		if (allow_add || allow_remove)
> +			die("--add, --replace and --swap do not play together");
> +		memset(&state, 0, sizeof(state));
> +		state.force = 1;
> +		state.not_new = 1;
> +		if (add_cache_entry(ce, 0))
> +			return error("%s: cannot add to the index", path);
> +		if (checkout_entry(old, &state, NULL))
> +			return error("%s: cannot swap", path);
> +		return 0;
> +	}
>  	option = allow_add ? ADD_CACHE_OK_TO_ADD : 0;
>  	option |= allow_replace ? ADD_CACHE_OK_TO_REPLACE : 0;
>  	if (add_cache_entry(ce, option))
> @@ -727,6 +741,8 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
>  			"let files replace directories and vice-versa", 1),
>  		OPT_SET_INT(0, "remove", &allow_remove,
>  			"notice files missing from worktree", 1),
> +		OPT_SET_INT(0, "swap", &swap_entry,
> +			"swap the content of index and worktree", 1),
>  		OPT_BIT(0, "unmerged", &refresh_args.flags,
>  			"refresh even if index contains unmerged entries",
>  			REFRESH_UNMERGED),