Re: [PATCH v8 2/2] [GSOC] trailer: add new .cmd config option

[ZheNing Hu <adlternative@gmail.com>]

Christian Couder <christian.couder@gmail.com> 于2021年4月10日周六 上午4:19写道：
>
> On Fri, Apr 9, 2021 at 3:37 PM ZheNing Hu via GitGitGadget
> <gitgitgadget@gmail.com> wrote:
> >
> > From: ZheNing Hu <adlternative@gmail.com>
> >
> > The `trailer.<token>.command` configuration variable
> > specifies a command (run via the shell, so it does not have
> > to be a single name of or path to the command, but can be a
>
> s/of or/or/
>
> > shell script), and the first occurrence of substring $ARG is
> > replaced with the value given to the `interpret-trailer`
> > command for the token.  This has two downsides:
>
> Maybe: s/for the token/for the token in a '--trailer <token>=<value>' argument/
>
> > * The use of $ARG in the mechanism misleads the users that
> > the value is passed in the shell variable, and tempt them
> > to use $ARG more than once, but that would not work, as
> > the second and subsequent $ARG are not replaced.
> >
> > * Because $ARG is textually replaced without regard to the
> > shell language syntax, even '$ARG' (inside a single-quote
> > pair), which a user would expect to stay intact, would be
> > replaced, and worse, if the value had an unmatched single
> > quote (imagine a name like "O'Connor", substituted into
> > NAME='$ARG' to make it NAME='O'Connor'), it would result in
> > a broken command that is not syntactically correct (or
> > worse).
> >
> > Introduce a new `trailer.<token>.cmd` configuration that
> > takes higher precedence to deprecate and eventually remove
> > `trailer.<token>.command`, which passes the value as an
> > argument to the command.  Instead of "$ARG", users can
> > refer to the value as positional argument, $1, in their
> > scripts.
>
> Good!
>
> > Helped-by: Junio C Hamano <gitster@pobox.com>
> > Helped-by: Christian Couder <christian.couder@gmail.com>
> > Signed-off-by: ZheNing Hu <adlternative@gmail.com>
> > ---
> >  Documentation/git-interpret-trailers.txt | 90 ++++++++++++++++++++----
> >  t/t7513-interpret-trailers.sh            | 84 ++++++++++++++++++++++
> >  trailer.c                                | 37 +++++++---
> >  3 files changed, 187 insertions(+), 24 deletions(-)
> >
> > diff --git a/Documentation/git-interpret-trailers.txt b/Documentation/git-interpret-trailers.txt
> > index 3e5aa3a65ae9..1a874a93f49b 100644
> > --- a/Documentation/git-interpret-trailers.txt
> > +++ b/Documentation/git-interpret-trailers.txt
> > @@ -236,21 +236,38 @@ trailer.<token>.command::
> >         be called to automatically add or modify a trailer with the
> >         specified <token>.
> >  +
> > -When this option is specified, the behavior is as if a special
> > -'--trailer <token>=<value>' argument was added at the beginning of
> > -the "git interpret-trailers" command, where <value> is taken to be the
> > -standard output of the specified command with any leading and trailing
> > -whitespace trimmed off.
> > +When this option is specified, the first occurrence of substring $ARG is
> > +replaced with the value given to the `interpret-trailer` command for the
> > +same token. It passes the value through `$ARG`, otherwise this option behaves
> > +in the same way as 'trailer.<token>.cmd'.
>
> Actually I think that we should say first that this behaves in the
> same way as the 'trailer.<token>.cmd'.
>
> And this should also replace the first paragraph in the description of
> 'trailer.<token>.command', not just the second one.
>

Make sence. After all, the primary purpose of this patch is to show that
".command" has been deprecated.

> Maybe:
>
> "This option behaves in the same way as 'trailer.<token>.cmd', except
> that it doesn't pass anything as argument to the specified command.
> Instead the first occurrence of substring $ARG is replaced by the
> value that would be passed as argument."
>
> > +The 'trailer.<token>.command' option has been deprecated due to the fact
>
> s/deprecated/deprecated in favor of 'trailer.<token>.cmd'/
>
> > +that $ARG in the user's command can only be replaced once and that the
>
> s/can only be/is only/
>
> > +original way of replacing $ARG was not safe.
>
> s/was/is/
>
> > Now the preferred option is 'trailer.<token>.cmd', which uses a positional argument to pass the value.
>
> I think we can remove this sentence especially if we say "deprecated
> in favor of 'trailer.<token>.cmd'" above.
>

I agree.

> > -The first occurrence of substring `$ARG` will be replaced with the
> > -<value> part of an existing trailer with the same <token>, if any,
> > -before the command is launched.
> > +When both 'trailer.<token>.cmd' and 'trailer.<token>.command' are given
> > +for the same <token>, 'trailer.<token>.cmd' is used and
> > +'trailer.<token>.command' is ignored.
>
> Ok.
>
> > +trailer.<token>.cmd::
>
> I think we should base the description of this option on what I
> suggest in patch 1/2. So let's agree on patch 1/2 before discussing
> this.

Yes, The description of the new .cmd is best approximated by
the .command in 1/2 .

I should @Junio, I don't know if he has any other opinions.

--
ZheNing Hu