Re: [PATCH] scalar: accept -C and -c options before the subcommand

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Taylor,

On Wed, 26 Jan 2022, Taylor Blau wrote:

> On Wed, Jan 26, 2022 at 11:15:29AM +0000, Johannes Schindelin via GitGitGadget wrote:
> > From: Johannes Schindelin <johannes.schindelin@gmx.de>
> >
> > The `git` executable has these two very useful options:
> >
> > -C <directory>:
> > 	switch to the specified directory before performing any actions
> >
> > -c <key>=<value>:
> > 	temporarily configure this setting for the duration of the
> > 	specified scalar subcommand
> >
> > With this commit, we teach the `scalar` executable the same trick.
> >
> > Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> > ---
> >     scalar: accept -C and -c options
> >
> >     This makes the scalar command a bit more handy by offering the same -c
> >     <key>=<value> and -C <directory> options as the git command.
> >
> > Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1130%2Fdscho%2Fscalar-c-and-C-v1
> > Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1130/dscho/scalar-c-and-C-v1
> > Pull-Request: https://github.com/gitgitgadget/git/pull/1130
> >
> >  contrib/scalar/scalar.c   | 22 +++++++++++++++++++++-
> >  contrib/scalar/scalar.txt | 10 ++++++++++
> >  2 files changed, 31 insertions(+), 1 deletion(-)
> >
> > diff --git a/contrib/scalar/scalar.c b/contrib/scalar/scalar.c
> > index 1ce9c2b00e8..7db2a97416e 100644
> > --- a/contrib/scalar/scalar.c
> > +++ b/contrib/scalar/scalar.c
> > @@ -808,6 +808,25 @@ int cmd_main(int argc, const char **argv)
> >  	struct strbuf scalar_usage = STRBUF_INIT;
> >  	int i;
> >
> > +	while (argc > 1 && *argv[1] == '-') {
> > +		if (!strcmp(argv[1], "-C")) {
> > +			if (argc < 3)
> > +				die(_("-C requires a <directory>"));
> > +			if (chdir(argv[2]) < 0)
> > +				die_errno(_("could not change to '%s'"),
> > +					  argv[2]);
> > +			argc -= 2;
> > +			argv += 2;
> > +		} else if (!strcmp(argv[1], "-c")) {
> > +			if (argc < 3)
> > +				die(_("-c requires a <key>=<value> argument"));
> > +			git_config_push_parameter(argv[2]);
> > +			argc -= 2;
> > +			argv += 2;
> > +		} else
> > +			break;
> > +	}
> > +
>
> All looks right to me based on a cursory scan. It's too bad that we have
> to copy this code from git.c::handle_options().

It's only a dozen lines, though, and they are pretty stable, so I doubt
that we risk divergent copied code.

> Could we call handle_options() (assuming that it was available to
> Scalar's compilation unit) instead? I'm not sure if that's a naive
> question or not, but it might be nice to explain it out in the commit
> message in case other reviewers have the same question that I did.

I just responded to Stolee elsewhere in this thread with a lengthy
analysis of the options, and the conclusion that it would not be worth the
effort to refactor `handle_options()`.

> On a more practical note: is there an easy way to test this?

It would be pretty easy to test `-C`:

	git init sub &&
	scalar -C sub register &&
	[... verify that `sub/` is now a Scalar repository ...]

For `-c`, we would need to configure something parsed by
`git_default_config()` that would influence what `scalar register` does,
then verify that. Or even better, use a config setting that is in the
"Optional" section of `set_recommended_config()`, i.e. it will refuse to
override an already-configured value. Something like `status.aheadBehind`.

I added this:

-- snip --
diff --git a/contrib/scalar/t/t9099-scalar.sh b/contrib/scalar/t/t9099-scalar.sh
index 2e1502ad45e..89781568f43 100755
--- a/contrib/scalar/t/t9099-scalar.sh
+++ b/contrib/scalar/t/t9099-scalar.sh
@@ -85,4 +85,12 @@ test_expect_success 'scalar delete with enlistment' '
 	test_path_is_missing cloned
 '

+test_expect_success 'scalar supports -c/-C' '
+	test_when_finished "scalar delete sub" &&
+	git init sub &&
+	scalar -C sub -c status.aheadBehind=bogus register &&
+	test -z "$(git -C sub config --local status.aheadBehind)" &&
+	test true = "$(git -C sub config core.preloadIndex)"
+'
+
 test_done
-- snap --

Ciao,
Dscho