Re: [PATCH] completion: add option completion for most builtin commands

[Junio C Hamano <gitster@pobox.com>]

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

> These commands can take options and use parse-options so it's quite
> easy to allow option completion. This does not pollute the command
> name completion though. "git <tab>" will show you the same set as
> before. This only kicks in when you type the correct command name.
>
> Some other builtin commands are not still added because either they
> don't use parse-options, or they are deprecated, or they are those
> -helper commands that are used to move some logic back in C for
> sh-based commands.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  contrib/completion/git-completion.bash | 276 +++++++++++++++++++++++++
>  1 file changed, 276 insertions(+)

Wow, just wow.  It however looks a lot of boilerplates, e.g. looking
at these, we notice ...

> +_git_blame() {
> +	case "$cur" in
> +	--*)
> +		__gitcomp_builtin blame
> +		return
> +		;;
> +	esac
> +}
> +
>  
> +_git_cat_file() {
> +	case "$cur" in
> +	--*)
> +		__gitcomp_builtin cat-file
> +		return
> +		;;
> +	esac
> +}
> +
> +_git_check_attr() {
> +	case "$cur" in
> +	--*)
> +		__gitcomp_builtin check-attr
> +		return
> +		;;
> +	esac
> +}

... the only thing we need for the above three is a table that says
"use blame for blame, cat-file for cat_file, and check-attr for
check_attr".

And that pattern repeats throughout the patch.  I wonder if we can
express the same a lot more concisely by updating the caller that
calls these command specific helpers?