Subject: Re: [PATCH 4/5] config.c: add a "tristate" helper

From: Junio C Hamano <[email-masked]>
Date: Thu, 08 Apr 2021 11:33:13 -0700

Ævar Arnfjörð Bjarmason  <[email-masked]> writes:

> Add "tristate" functions to go along with the "bool" functions and
> migrate the common pattern of checking if something is "bool" or
> "auto" in various places over to the new functions.
>
> We also have e.g. "repo_config_get_bool" and
> "config_error_nonbool". I'm not adding corresponding "tristate"
> functions as they're not needed by anything, but we could add those in
> the future if they are.
>
> I'm not migrating over "core.abbrev" parsing as part of this
> change. When "core.abbrev" was made optionally boolean in
> a9ecaa06a7 (core.abbrev=no disables abbreviations, 2020-09-01) the
> "die if empty" code added in g48d5014dd4 (config.abbrev: document the
> new default that auto-scales, 2016-11-01) wasn't adjusted. It thus
> behaves unlike all other "maybe bool" config variables.
>
> I have a planned series to start adding some tests for "core.abbrev",
> but AFAICT there's not even a test for "core.abbrev=true", and I'd
> like to focus on thing that have no behavior change here, so let's
> leave it for now.
>
> Signed-off-by: Ævar Arnfjörð Bjarmason <[email-masked]>
> ---
>  builtin/log.c  | 13 +++++++------
>  compat/mingw.c |  6 +++---
>  config.c       | 16 ++++++++++++++++
>  config.h       | 12 ++++++++++++
>  http.c         |  5 +++--
>  userdiff.c     |  6 ++----
>  6 files changed, 43 insertions(+), 15 deletions(-)

> diff --git a/config.c b/config.c
> index fc28dbd97c..74d2b2c0df 100644
> --- a/config.c
> +++ b/config.c
> @@ -1257,6 +1257,14 @@ int git_parse_maybe_bool(const char *value)
>  	return -1;
>  }
>  
> +int git_parse_maybe_tristate(const char *value)
> +{
> +	int v = git_parse_maybe_bool(value);
> +	if (v < 0 && !strcasecmp(value, "auto"))
> +		return 2;
> +	return v;
> +}

This is not parse_mayb_bool_text(), so "1" and "-1" written in the
configuration file are "true", "0" is "false", like the "bool" case.

I wonder if written without an unnecessary extra variable, i.e.

	if (value && !strcasecmp(value, "auto"))
		return 2;
	return git_parse_maybe_bool(value);

is easier to follow, though, as it is quite clear that it is mostly
the same as maybe_bool and the only difference is when "auto" is
given.

> +int git_config_tristate(const char *name, const char *value)
> +{
> +	int v = git_parse_maybe_tristate(value);
> +	if (v < 0)
> +		die(_("bad tristate config value '%s' for '%s'"), value, name);
> +	return v;
> +}

OK.

> diff --git a/config.h b/config.h
> index 19a9adbaa9..c5129e4392 100644
> --- a/config.h
> +++ b/config.h
> @@ -197,6 +197,12 @@ int git_parse_ulong(const char *, unsigned long *);
>   */
>  int git_parse_maybe_bool(const char *);
>  
> +/**
> + * Same as `git_parse_maybe_bool`, except that "auto" is recognized and
> + * will return "2".
> + */
> +int git_parse_maybe_tristate(const char *);

A false being 0 and a true being 1 is understandable for readers
without symbolic constant, but "2" deserves to have a symbolic
constant, doesn't it?

> @@ -226,6 +232,12 @@ int git_config_bool_or_int(const char *, const char *, int *);
>   */
>  int git_config_bool(const char *, const char *);
>  
> +/**
> + * Like git_config_bool() except "auto" is also recognized and will
> + * return "2"
> + */
> +int git_config_tristate(const char *, const char *);

Likewise.

Thanks.