Re: [PATCH v4 3/3] builtin/config: introduce `color` type specifier

> 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.
> 
> 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 --type=color core.section
> 
> will be have exactly as:
> 
>   $ git config --get-color core.section red
> 
> For consistency, let's introduce `--color` and encourage `--type=color`,
> `--default` together over `--get-color` alone.

> Signed-off-by: Taylor Blau <me@ttaylorr.com>
> ---
>  Documentation/git-config.txt | 10 ++++++----
>  builtin/config.c             | 21 +++++++++++++++++++++
>  t/t1300-repo-config.sh       | 30 ++++++++++++++++++++++++++++++
>  3 files changed, 57 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
> index 620492d1e..bde702d2e 100644
> --- a/Documentation/git-config.txt
> +++ b/Documentation/git-config.txt
> @@ -38,10 +38,8 @@ existing values that match the regexp are updated or unset.  If
>  you want to handle the lines that do *not* match the regex, just
>  prepend a single exclamation mark in front (see also <<EXAMPLES>>).
>  
> -A type specifier may be given as an argument to `--type` to make 'git config'
> -ensure that the variable(s) are of the given type and convert the value to the
> -canonical form. If no type specifier is passed, no checks or transformations are
> -performed on the value.
> +`color`::
> +    The value is taken as an ANSI color escape sequence.

>  When reading, the values are read from the system, global and
>  repository local configuration files by default, and options
> @@ -177,6 +175,7 @@ Valid `<type>`'s include:
>    ~/` from the command line to let your shell do the expansion.)
>  - 'expiry-date': canonicalize by converting from a fixed or relative date-string
>    to a timestamp. This specifier has no effect when setting the value.
> +- 'color': canonicalize by converting to an ANSI color escape sequence.
>  +

> diff --git a/builtin/config.c b/builtin/config.c
> index 1328b568b..aa3fcabe9 100644
> --- a/builtin/config.c
> +++ b/builtin/config.c
> @@ -61,6 +61,7 @@ static int show_origin;
>  #define TYPE_BOOL_OR_INT	3
>  #define TYPE_PATH		4
>  #define TYPE_EXPIRY_DATE	5
> +#define TYPE_COLOR		6

> @@ -203,6 +206,11 @@ static int format_config(struct strbuf *buf, const char *key_, const char *value
>  			if (git_config_expiry_date(&t, key_, value_) < 0)
>  				return -1;
>  			strbuf_addf(buf, "%"PRItime, t);
> +		} else if (type == TYPE_COLOR) {
> +			char v[COLOR_MAXLEN];
> +			if (git_config_color(v, key_, value_) < 0)
> +				return -1;
> +			strbuf_addstr(buf, v);
>  		} else if (value_) {
>  			strbuf_addstr(buf, value_);
>  		} else {

> @@ -348,6 +356,19 @@ static char *normalize_value(const char *key, const char *value)
>  		else
>  			return xstrdup(v ? "true" : "false");
>  	}
> +	if (type == TYPE_COLOR) {
> +		char v[COLOR_MAXLEN];
> +		if (!git_config_color(v, key, value))
> +			/*
> +			 * The contents of `v` now contain an ANSI escape
> +			 * sequence, not suitable for including within a
> +			 * configuration file. Treat the above as a
> +			 * "sanity-check", and return the given value, which we
> +			 * know is representable as valid color code.
> +			 */
> +			return xstrdup(value);
> +		die("cannot parse color '%s'", value);
> +	}