Re: [PATCH/RFC] completion: complete all possible -no-<options>

[Andreas Heiduk <asheiduk@gmail.com>]

Am 14.05.2018 um 19:26 schrieb Duy Nguyen:
> On Mon, May 14, 2018 at 7:03 PM, Andreas Heiduk <asheiduk@gmail.com> wrote:
>> Am 08.05.2018 um 17:24 schrieb Duy Nguyen:
>>> On Mon, Apr 23, 2018 at 7:36 AM, Eric Sunshine <sunshine@sunshineco.com> wrote:
>>>> I haven't looked at the implementation, so this may be an entirely
>>>> stupid suggestion, but would it be possible to instead render the
>>>> completions as?
>>>>
>>>>     % git checkout --<tab>
>>>>     --[no-]conflict=                   --[no-]patch
>>>>     --[no-]detach                      --[no-]progress
>>>>     --[no-]ignore-other-worktrees      --[no-]quiet
>>>>     --[no-]ignore-skip-worktree-bits   --[no-]recurse-submodules
>>>>     --[no-]merge                       --theirs
>>>>     --[no-]orphan=                     --[no-]track
>>>>     --ours
>>>>
>>>> This would address the problem of the --no-* options taking double the
>>>> screen space.
>>>
>>> It took me so long to reply partly because I remember seeing some guy
>>> doing clever trick with tab completion that also shows a short help
>>> text in addition to the complete words. I could not find that again
>>> and from my reading (also internet searching) it's probably not
>>> possible to do this without trickery.
>>
>> The fish-shell does something like that.
>>
>>     > git status --<tab here>
>>     --branch  (Show the branch and tracking info even in short-format)
>>     --help                       (Display the manual of a git command)
>>     --ignore-submodules                 (Ignore changes to submodules)
>>     --porcelain    (Give the output in a stable, easy-to-parse format)
>>     --short                      (Give the output in the short-format)
>>     --untracked-files              (The untracked files handling mode)
>>
>> Another tab will put a selection-cursor on the displayed list - you can
>> navigate that list with Cursor-Up/Cursor-Down, select an entry and that
>> entry will be inserted into the commandline. That selection process
>> would be useless if the options are presented as "--[no-]x" because THAT
>> cannot be inserted into the commandline without manual editing. And
>> that's the point of the fast option selection process.
> 
> Good to know.
> 
> BTW I looked at the git.fish completion script [1] and see that recent
> effort to help automate more in git-completion.bash might help there
> too. I notice a lot of options and help text hard coded there, if
> someone can explain to me how git.fish uses those, maybe I can change
> git to export something suitable for git.fish to use too [2].

I'm no expert, but some additional things required by fish (and I
suppose zsh too) but not by bash:

- grouping of long and short options
- help text
- argument types for options

Help text and long/short option grouping look like this:

    > git rebase -<tab>
    --force-rebase  -f                                (Force the rebase)
    --merge  -m                       (Use merging strategies to rebase)

All these infos seem to be available in `struct option` (for C stuff
at least). So I guess It would be easiest for Fish & Co if git just
exports the complete info in some stable format.

> 
> For example with latest git (in 'master') doing this
> 
>     ./git add --git-completion-helper
> 
> gives you the list of all options of "git add". Giving the help text
> for each option is definitely possible (I just didn't see any use for
> it until I looked at zsh/fish completion scripts) and maybe more in
> the future.
> 
> [1] https://github.com/fish-shell/fish-shell/blob/master/share/completions/git.fish
> [2] But then if your script has to work with old git versions too then
> this is a moot point.

Well, sooner or later those old git versions might not be supported by
those shells exactly due to the involved maintenance overhead. So
providing some helper is a step in the right direction. Not providing
only fossilizes the current state.