Re: [PATCH v2] submodule: port subcommand 'set-branch' from shell to C

From: Shourya Shukla <shouryashukla.oo@gmail.com>
Date: May 20, 2020, 12:15 UTC
Message-ID: <20200520121530.GA7992@konoha>
In-Reply-To: <CAPig+cSKFBFdNXA52f5f0q3SetA2btmkXeqyHNw-qwJ5ECq5mQ@mail.gmail.com>

Hello Eric!

On 19/05 02:57, Eric Sunshine wrote:

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> On Tue, May 19, 2020 at 2:27 PM Shourya Shukla
> <shouryashukla.oo@gmail.com> wrote:
> > Convert submodule subcommand 'set-branch' to a builtin. Port 'set-branch'
> > to 'submodule--helper.c' and call the latter via 'git-submodule.sh'.
> 
> You can reduce the redundancy by writing this as:
> 
>     Convert git-submodule subcommand 'set-branch' to a builtin and
>     call it via 'git-submodule.sh'.

Sure! Will do!

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> > +       struct option options[] = {
> > +               OPT__QUIET(&quiet,
> > +                       N_("suppress output for setting default tracking branch of a submodule")),
> 
> This is unusually verbose for a _short_ description of the option.
> Other commands use simpler descriptions. Perhaps take a hint from the
> git-submodule man page:
> 
>     N("only print error messages")),
> 
> However, the bigger question is: Why is the --quiet option even here?
> None of the code in this function ever consults the 'quiet' variable,
> so its presence seems pointless.

I actually wanted to have *some* use of the `quiet` option and delivered it in the v1, but after some feedback had to scrap it. You may have a look here: https://lore.kernel.org/git/20200513201737.55778-2-shouryashukla.oo@gmail.com/

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> Looking at the git-submodule documentation, I see that it is already
> documented as accepted --quiet, so it may make some sense for you to
> accept the option here. However, it might be a good idea either to
> have an in-code comment or a blurb in the commit message explaining
> that this C rewrite accepts the option for backward-compatibility (and
> for future extension), not because it is actually used presently.

That seems like a better idea; should I add this comment just above the `options` array? BTW, the shell version has a comment about this, see: https://github.com/git/git/blob/v2.26.2/git-submodule.sh#L727

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> > +               OPT_STRING(0, "branch", &opt_branch, N_("branch"),
> > +                       N_("set the default tracking branch to the one specified")),
> 
> Then:
> 
>     N_("set the default tracking branch")),

Seems good!

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> > +               OPT_END()
> > +       };
> > +       const char *const usage[] = {
> > +               N_("git submodule--helper set-branch [--quiet] (-d|--default) <path>"),
> > +               N_("git submodule--helper set-branch [--quiet] (-b|--branch) <branch> <path>"),
> > +               NULL
> > +       };
> > +
> > +       argc = parse_options(argc, argv, prefix, options, usage, 0);
> > +
> > +       if (!opt_branch && !opt_default)
> > +               die(_("at least one of --branch and --default required"));
> 
> This wording makes no sense considering that --branch and --default
> are mutually exclusive. By writing "at least one of", you're saying
> that you can use _more than one_, which is clearly incorrect. Reword
> it like this:
> 
>     die(_("--branch or --default required"));

Yeah, I did not realize it until you mentioned this, will correct in the next version.

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> > +       if (opt_branch && opt_default)
> > +               die(_("--branch and --default do not make sense together"));
> 
> A more precise way to say this is:
> 
>     die(_("--branch and --default are mutually exclusive"));

Will that be clear to everyone? What I mean is maybe a person from a non-mathematical background (someone doing programming as a hobby maybe) will not grasp at this at one go and will have to search it's meaning online. Isn't it fine as-is?

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> > +       if (argc != 1 || !(path = argv[0]))
> > +               usage_with_options(usage, options);
> > +
> > +       config_name = xstrfmt("submodule.%s.branch", path);
> > +       config_set_in_gitmodules_file_gently(config_name, opt_branch);
> 
> Tracing through the config code, I see that
> config_set_in_gitmodules_file_gently() removes the key if 'opt_branch'
> is NULL, which mirrors the behavior of the shell code this is
> replacing. Good.

Thanks! :)

Regards, Shourya Shukla