Subject: Re: [PATCH v2 4/4] builtin/config: introduce `--color` type specifier

From: Taylor Blau <[email-masked]>
Date: Wed, 28 Mar 2018 18:36:46 -0700

On Mon, Mar 26, 2018 at 05:16:45AM -0400, Jeff King wrote:
> On Fri, Mar 23, 2018 at 08:55:56PM -0400, Taylor Blau wrote:
>
> > As of this commit, the canonical way to retreive an ANSI-compatible
> > color escape sequence from a configuration file is with the
> > `--get-color` action.
>
> s/retreive/retrieve/

Ack. I forgot to correct this in v3. I will remember to fix this in
anticipation of v4 before this is queued.

> > This is to allow Git to "fall back" on a default value for the color
> > should the given section not exist in the specified configuration(s).
> >
> > With the addition of `--default`, this is no longer needed since:
> >
> >   $ git config --default red --color core.section
> >
> > will be have exactly as:
> >
> >   $ git config --get-color core.section red
> >
> > For consistency, let's introduce `--color` and encourage `--color`,
> > `--default` together over `--get-color` alone.
>
> I don't think we'll ever get rid of --get-color (at the very least, we'd
> need a deprecation period). But it's probably worth adding a note under
> the --get-color description to mention that it's a historical synonym,
> and that using "--default" should be preferred.

I added a note in v3 under the `--get-color` section that it is now
considered "historical", and it is instead preferred to use

  $ git config --default=<default> --type=color <section>

> > @@ -90,6 +91,7 @@ static struct option builtin_config_options[] = {
> >  	OPT_BIT(0, "bool-or-int", &types, N_("value is --bool or --int"), TYPE_BOOL_OR_INT),
> >  	OPT_BIT(0, "path", &types, N_("value is a path (file or directory name)"), TYPE_PATH),
> >  	OPT_BIT(0, "expiry-date", &types, N_("value is an expiry date"), TYPE_EXPIRY_DATE),
> > +	OPT_BIT(0, "color", &types, N_("value is a color"), TYPE_COLOR),
> >  	OPT_GROUP(N_("Other")),
> >  	OPT_BOOL('z', "null", &end_null, N_("terminate values with NUL byte")),
> >  	OPT_BOOL(0, "name-only", &omit_values, N_("show variable names only")),
>
> I just had a funny thought. Normally in Git the "--color" option means
> "colorize the output". And we are diverging from that here. I wonder if
> anybody would be confused by that, or if we would ever want to later add
> an option to colorize git-config output. Would we regret squatting on
> --color?
>
> I'm not sure what else to name it. Anything _except_ "--color" would
> diverge from the existing scheme of "--<type>".
>
> If we were designing from scratch, I'd consider:
>
>   git config --type=int ...
>   git config --type=color ...
>
> etc. I'm not sure if it's worth trying to switch now (on the other hand,
> it resolves the documentation issue I mentioned earlier, since that
> would naturally group all of the types ;) ).
>
> It would be pretty easy to declare "--type" as the Right Way, and list
> "--int" as a historical synonym for "--type=int".

Agreed. I have posted a topic to the list containing a patch to the
above effect.

> > @@ -320,6 +327,12 @@ static char *normalize_value(const char *key, const char *value)
> >  		else
> >  			return xstrdup(v ? "true" : "false");
> >  	}
> > +	if (types == TYPE_COLOR) {
> > +		char v[COLOR_MAXLEN];
> > +		if (!git_config_color(v, key, value))
> > +			return xstrdup(value);
> > +		die("cannot parse color '%s'", value);
> > +	}
>
> Interesting. This doesn't actually normalize anything, since we always
> pass back the original value (or die). I think that's the right thing to
> do, since otherwise you'd end up with ANSI codes in your config file.
>
> I wondered at first if this should go in the "noop" normalization that
> TYPE_PATH undergoes. But I like that it actually sanity-checks the
> value. We should probably have a comment here explaining that yes, we
> parse and then throw away the value (similar to the one near TYPE_PATH).

That was my original intent, but I agree that this is confusing without
a comment explaining so. I have added such a comment in v3.

> I suspect that TYPE_EXPIRY_DATE should do the same thing (parse and
> complain if you fed nonsense, but always keep the original value).

Where?

> > +test_expect_success 'get --color' '
> > +	rm .git/config &&
> > +	git config foo.color "red" &&
> > +	git config --get --color foo.color | test_decode_color >actual &&
> > +	echo "<RED>" >expect &&
> > +	test_cmp expect actual
> > +'
>
> We should probably write this as:
>
>   git config --get --color foo.color >actual.raw &&
>   test_decode_color <actual.raw >actual
>
> to catch failures from git-config itself (there's a lot of old tests
> which pipe, but we've been trying to convert them to be more careful).

Sounds good; I have added this in v3.

> > +test_expect_success 'set --color' '
> > +	rm .git/config &&
> > +	git config --color foo.color "red" &&
> > +	test_cmp expect .git/config
> > +'
> > +
> > +test_expect_success 'get --color barfs on non-color' '
> > +	echo "[foo]bar=not-a-color" >.git/config &&
> > +	test_must_fail git config --get --color foo.bar
> > +'
>
> After reading the normalize bits above, I think there's one more case to
> cover:
>
>   test_must_fail git config --color foo.color not-a-color

Good idea, I've added this in v3.

> > diff --git a/t/t1310-config-default.sh b/t/t1310-config-default.sh
> > index 0e464c206..0ebece7d2 100755
> > --- a/t/t1310-config-default.sh
> > +++ b/t/t1310-config-default.sh
> > @@ -62,6 +62,12 @@ test_expect_success 'marshal default value as expiry-date' '
> >  	test_cmp expect actual
> >  '
> >
> > +test_expect_success 'marshal default value as color' '
> > +	echo "\033[31m" >expect &&
> > +	git config --default red --color core.foo >actual &&
> > +	test_cmp expect actual
> > +'
>
> I don't offhand recall whether octal escapes with "echo" are portable.
> It _is_ in POSIX, but only for XSI. I think using "printf" would be
> portable.

I removed this test in accordance with your earlier suggestions, so this
change is no longer required.

Thanks,
Taylor