Re: [PATCH v4] [GSOC]trailer: pass arg as positional parameter

[ZheNing Hu <adlternative@gmail.com>]

Junio C Hamano <gitster@pobox.com> 于2021年4月2日周五 上午3:49写道：
>
> ZheNing Hu <adlternative@gmail.com> writes:
>
> >> The way to do the same without an extra script on disk is for you to
> >> use sh-c yourself.
> >>
> >>     .cmd = sh -c 'echo 123'
> >
> > This is indeed a viable solution, But the extra "sh -c" seems to put an
> > unnecessary burden on the user.
>
> Nobody forces you to write long script in the configuration file.
> In fact, the "find author from history" is so useful that I'd think
> people have an alias or a script in ~/bin/ already for their own
> interactive use.  E.g.
>
>     $ cat ~/bin/git-who
>     #!/bin/sh
>     git log -1 --format="%an <%ae>" --author="$1"
>     $ cat ~/bin/git-one
>     #!/bin/sh
>     git show -s --pretty=reference "$1"
>
> and with them:
>
>         trailer.key.cmd = git who
>
> that is internally wrapped into
>
>         sh -c 'git who "$@"'
>
> and fed "gitster@" as the first parameter when "--trailer=key:gitster@"
> is given would work just fine.
>

Okay, now I get it. This allows us to run some common scripts or just use
"sh -c". I might need some additional tests to illustrate those changes made
by using '.cmd'.

> > Sometimes I wonder, why not recommend using environment variables
> > like $ARG?
>
> I am also fine with that; when we discovered the design flaw of
> .command, I think I suggested either would make a viable choice.
> The only downside is that it would squat on a good name $ARG and
> forbids end-users from using the symbol for other purpose, but as
> long as the application is limited in scope, that would be fine.

I agree with you. This may indeed be a minor drawback.

Thanks, Junio.

--
ZheNing Hu