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From: David Aguilar <davvid@gmail.com>
To: ZheNing Hu via GitGitGadget <gitgitgadget@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>,
	Denton Liu <liu.denton@gmail.com>,
	John Keeping <john@keeping.me.uk>,
	Junio C Hamano <gitster@pobox.com>,
	ZheNing Hu <adlternative@gmail.com>,
	Ryan Zoeller <rtzoeller@rtzoeller.com>
Subject: Re: [PATCH v2] git-difftool-helper.sh: learn a new way go back to last save point
Date: Mon, 8 Feb 2021 14:15:28 -0800	[thread overview]
Message-ID: <CAJDDKr4AyxuS-MQ+62XGnK4UvJ+cFDdnMwOK1GSn-oiFrWoxyw@mail.gmail.com> (raw)
In-Reply-To: <pull.870.v2.git.1612803744188.gitgitgadget@gmail.com>

(cc'd Ryan since the thread involving him was mentioned in the commit message)

On Mon, Feb 8, 2021 at 9:02 AM ZheNing Hu via GitGitGadget
<gitgitgadget@gmail.com> wrote:
>
> From: ZheNing Hu <adlternative@gmail.com>
>
> `git difftool` only allow us to select file to view in turn.
> If there is a commit with many files and we exit in the search,
> We will have to traverse list again to get the file diff which
> we want to see. Therefore, here is a new method: every time before
> we view the file diff, the current coordinates will be stored in
> `GIT_DIR/difftool-last-position`, this file will be deleted after
> successful traversing. But if an unexpected exit occurred midway or
> users similar to using "ctrl+c" kill the process,and the user wants
> to redo the same `git difftoool`, git will view the coordinates in
> the save point, ask user if they want continue from the last position.
> This will improve the user experience.
>
> Signed-off-by: ZheNing Hu <adlternative@gmail.com>
> ---
>     git-difftool-helper.sh: learn a new way skip to save point
>
>     git user may should travel the diff list to choice file diff to view, if
>     they exit in midway,they must travel it again. By saving current
>     coordinates in GIT_DIR/difftool-last-position method, provides a
>     possibility for this user-friendly solution.
>
>     this patch's origin discuss is here:
>     https://lore.kernel.org/git/gOXOaoqn-E9A2ob7ykWEcDc7ZxmSwAjcP5CCFKfr5ejCOWZQ1lfAUZcbgYT9AyQCcDgJvCrnrtziXiels-Hxol3xlkGTVHk24SvAdaSUtKQ=@rtzoeller.com/
>
>     Thanks!
>
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-870%2Fadlternative%2Fdifftool_save_point-v2
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-870/adlternative/difftool_save_point-v2
> Pull-Request: https://github.com/gitgitgadget/git/pull/870
>
> Range-diff vs v1:
>
>  1:  e77c3e33ba85 ! 1:  2468eaff322b git-difftool-helper.sh: learn a new way skip to save point
>      @@ Metadata
>       Author: ZheNing Hu <adlternative@gmail.com>
>
>        ## Commit message ##
>      -    git-difftool-helper.sh: learn a new way skip to save point
>      +    git-difftool-helper.sh: learn a new way go back to last save point
>
>      -    `git difftool` only allow us to select file to view In turn.
>      -    If there is a commit with many files and we exit in search,
>      +    `git difftool` only allow us to select file to view in turn.
>      +    If there is a commit with many files and we exit in the search,
>           We will have to traverse list again to get the file diff which
>      -    we want to see.Therefore,here is a new method:every time before
>      -    we view the file diff,the current coordinates will be stored in
>      -    `GIT_DIR/difftool_skip_to`,this file will be deleted after
>      -    successful traversing.But if an unexpected exit occurred midway,
>      -    git will view the coordinates in the save point,ask user if they
>      -    want continue from the last saved point.This will improve the
>      -    user experience.
>      +    we want to see. Therefore, here is a new method: every time before
>      +    we view the file diff, the current coordinates will be stored in
>      +    `GIT_DIR/difftool-last-position`, this file will be deleted after
>      +    successful traversing. But if an unexpected exit occurred midway or
>      +    users similar to using "ctrl+c" kill the process,and the user wants
>      +    to redo the same `git difftoool`, git will view the coordinates in
>      +    the save point, ask user if they want continue from the last position.
>      +    This will improve the user experience.
>
>           Signed-off-by: ZheNing Hu <adlternative@gmail.com>
>
>      @@ git-difftool--helper.sh
>        # Copyright (c) 2009, 2010 David Aguilar
>
>        TOOL_MODE=diff
>      -+GIT_DIFFTOOL_SKIP_TO_FILE="$GIT_DIR/difftool-skip-to"
>      ++GIT_DIFFTOOL_LAST_POSITION="$GIT_DIR/difftool-last-position"
>      ++DIFFTOOL_FIRST_NUM="1"
>        . git-mergetool--lib
>
>        # difftool.prompt controls the default prompt/no-prompt behavior
>      @@ git-difftool--helper.sh: launch_merge_tool () {
>         # the user with the real $MERGED name before launching $merge_tool.
>         if should_prompt
>         then
>      -+         if test -f "$GIT_DIFFTOOL_SKIP_TO_FILE"
>      ++         if test -f "$GIT_DIFFTOOL_LAST_POSITION"
>       +         then
>      -+                 SAVE_POINT_NUM=$(cat "$GIT_DIFFTOOL_SKIP_TO_FILE")
>      -+                 if test $SAVE_POINT_NUM -le $GIT_DIFF_PATH_TOTAL &&
>      -+                         test $SAVE_POINT_NUM -gt $GIT_DIFF_PATH_COUNTER
>      ++                 if SAVE_POINT_NUM=$(cat 2>/dev/null "$GIT_DIFFTOOL_LAST_POSITION") &&
>      ++                         test "$SAVE_POINT_NUM" -le "$GIT_DIFF_PATH_TOTAL" &&
>      ++                                 test "$SAVE_POINT_NUM" -gt "$GIT_DIFF_PATH_COUNTER"
>       +                 then
>      -+                         # choice skip or not skip when check first file.
>      -+                         if test $GIT_DIFF_PATH_COUNTER -eq "1"
>      ++                         if test "$GIT_DIFF_PATH_COUNTER" -eq "$DIFFTOOL_FIRST_NUM"
>       +                         then
>      -+                                 printf "do you want to skip to last time difftool save point($SAVE_POINT_NUM) [Y/n]?"
>      ++                                 printf "Do you want to start from the possible last file you were viewing? [Y/n]?"
>       +                                 read skip_ans || return
>       +                                 if test "$skip_ans" = y
>       +                                 then
>      @@ git-difftool--helper.sh: launch_merge_tool () {
>       +                         fi
>       +                 fi
>       +         fi


Similar to Junio's question about, "where does this possible come
from?", I wasn't able to make out the behavior in the following
situation.

What about when the user switches branches or specifies a pathspec on
the command-line or some other avenue that ends up with the number of
files to diff being very different than the last difftool invocation?

Will difftool, for example, skip over a smaller set of files on
invocation 2 if invocation 1 involved many files and we exited out
with a counter number that is very high?

One thing that's not too good about having state files in .git/ is
that they're global data and we also have to think about, "what if the
user has multiple difftools running?" and those kind of complexities.

I don't want this to seem like I'm trying to be dismissive of this
feature which does seem like a useful thing in general, so I'll try to
come up with an alternative interface that is slightly more general
but a admittedly a little bit more cumbersome because it's not as
automatic.

What if instead of global state, maybe the user could specify a path
that difftool could skip forward to?   For example, we could teach
difftool to resume by telling it where we last left off:

   git difftool --resume-from=foo/bar099.txt

Then we don't need the global counter state file?


Finally, I'm going to plug what I believe to be the right tool for the
job here.  Have you tried git cola?[1]  Difftool is tightly
integrated, and the UI is such that you can trivially choose any of
the modified/staged files and difftool them by using the Ctrl-d
hotkey.

https://github.com/git-cola/git-cola/

Cola is purpose-built for driving difftool, and for interactive
staging, so not mentioning it in the context of wanting a better UI
for difftool would be a disservice to difftool users.
-- 
David

  parent reply	other threads:[~2021-02-08 22:17 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-07 15:19 [PATCH] git-difftool-helper.sh: learn a new way skip to save point 阿德烈 via GitGitGadget
2021-02-07 18:29 ` Junio C Hamano
2021-02-07 19:04 ` Junio C Hamano
2021-02-08  8:06   ` 胡哲宁
2021-02-08 17:02 ` [PATCH v2] git-difftool-helper.sh: learn a new way go back to last " ZheNing Hu via GitGitGadget
2021-02-08 20:13   ` Junio C Hamano
2021-02-08 22:15   ` David Aguilar [this message]
2021-02-08 23:34     ` Junio C Hamano
2021-02-09  6:19       ` 胡哲宁
2021-02-09  6:04     ` 胡哲宁
2021-02-09 15:30   ` [PATCH v3] difftool.c: learn a new way start from specified file ZheNing Hu via GitGitGadget
2021-02-09 18:17     ` Junio C Hamano
2021-02-10 17:00       ` 胡哲宁
2021-02-10 18:16         ` Junio C Hamano
2021-02-10 20:05           ` Junio C Hamano
2021-02-14  7:53           ` ZheNing Hu
2021-02-14 13:09     ` [PATCH v4] difftool.c: learn a new way start at " ZheNing Hu via GitGitGadget
2021-02-16  1:46       ` Junio C Hamano
2021-02-16 12:56       ` [PATCH v5 0/2] " ZheNing Hu via GitGitGadget
2021-02-16 12:56         ` [PATCH v5 1/2] diff: --{rotate,skip}-to=<path> Junio C Hamano via GitGitGadget
2021-02-16 12:56         ` [PATCH v5 2/2] difftool.c: learn a new way start at specified file ZheNing Hu via GitGitGadget
2021-02-17 10:31           ` Junio C Hamano
2021-02-17 16:18             ` ZheNing Hu
2021-02-16 18:45         ` [PATCH v5 0/2] " Junio C Hamano
2021-02-17  4:12           ` ZheNing Hu
2021-02-17 11:14             ` Denton Liu
2021-02-17 11:40               ` ZheNing Hu
2021-02-17 18:56                 ` Junio C Hamano
2021-02-18  5:20                   ` ZheNing Hu
2021-02-18 15:04                   ` ZheNing Hu
2021-02-18 19:11                     ` Junio C Hamano
2021-02-19 10:59                       ` ZheNing Hu
2021-02-25 11:08                   ` Johannes Schindelin
2021-02-25 19:01                     ` Junio C Hamano
2021-02-19 12:53         ` [PATCH v6] " ZheNing Hu via GitGitGadget
2021-02-22 15:11           ` ZheNing Hu
2021-02-22 21:40           ` Junio C Hamano

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