Re: [PATCH v2] git-difftool-helper.sh: learn a new way go back to last save point

>
> 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