),
		),
		'type'         => 'string',
		'description'  => __( 'Allow people to post comments on new articles.' ),
	) );

}

/**
 * Register a setting and its data.
 *
 * @since 2.7.0
 * @since 4.7.0 `$args` can be passed to set flags on the setting, similar to `register_meta()`.
 *
 * @global array $new_whitelist_options
 * @global array $wp_registered_settings
 *
 * @param string $option_group A settings group name. Should correspond to a whitelisted option key name.
 * 	Default whitelisted option key names include "general," "discussion," and "reading," among others.
 * @param string $option_name The name of an option to sanitize and save.
 * @param array  $args {
 *     Data used to describe the setting when registered.
 *
 *     @type string   $type              The type of data associated with this setting.
 *                                       Valid values are 'string', 'boolean', 'integer', and 'number'.
 *     @type string   $description       A description of the data attached to this setting.
 *     @type callable $sanitize_callback A callback function that sanitizes the option's value.
 *     @type bool     $show_in_rest      Whether data associated with this setting should be included in the REST API.
 *     @type mixed    $default           Default value when calling `get_option()`.
 * }
 */
function register_setting( $option_group, $option_name, $args = array() ) {
	global $new_whitelist_options, $wp_registered_settings;

	$defaults = array(
		'type'              => 'string',
		'group'             => $option_group,
		'description'       => '',
		'sanitize_callback' => null,
		'show_in_rest'      => false,
	);

	// Back-compat: old sanitize callback is added.
	if ( is_callable( $args ) ) {
		$args = array(
			'sanitize_callback' => $args,
		);
	}

	/**
	 * Filters the registration arguments when registering a setting.
	 *
	 * @since 4.7.0
	 *
	 * @param array  $args         Array of setting registration arguments.
	 * @param array  $defaults     Array of default arguments.
	 * @param string $option_group Setting group.
	 * @param string $option_name  Setting name.
	 */
	$args = apply_filters( 'register_setting_args', $args, $defaults, $option_group, $option_name );
	$args = wp_parse_args( $args, $defaults );

	if ( ! is_array( $wp_registered_settings ) ) {
		$wp_registered_settings = array();
	}

	if ( 'misc' == $option_group ) {
		_deprecated_argument( __FUNCTION__, '3.0.0',
			/* translators: %s: misc */
			sprintf( __( 'The "%s" options group has been removed. Use another settings group.' ),
				'misc'
			)
		);
		$option_group = 'general';
	}

	if ( 'privacy' == $option_group ) {
		_deprecated_argument( __FUNCTION__, '3.5.0',
			/* translators: %s: privacy */
			sprintf( __( 'The "%s" options group has been removed. Use another settings group.' ),
				'privacy'
			)
		);
		$option_group = 'reading';
	}

	$new_whitelist_options[ $option_group ][] = $option_name;
	if ( ! empty( $args['sanitize_callback'] ) ) {
		add_filter( "sanitize_option_{$option_name}", $args['sanitize_callback'] );
	}
	if ( array_key_exists( 'default', $args ) ) {
		add_filter( "default_option_{$option_name}", 'filter_default_option', 10, 3 );
	}

	$wp_registered_settings[ $option_name ] = $args;
}

/**
 * Unregister a setting.
 *
 * @since 2.7.0
 * @since 4.7.0 `$sanitize_callback` was deprecated. The callback from `register_setting()` is now used instead.
 *
 * @global array $new_whitelist_options
 *
 * @param string   $option_group      The settings group name used during registration.
 * @param string   $option_name       The name of the option to unregister.
 * @param callable $deprecated        Deprecated.
 */
function unregister_setting( $option_group, $option_name, $deprecated = '' ) {
	global $new_whitelist_options, $wp_registered_settings;

	if ( 'misc' == $option_group ) {
		_deprecated_argument( __FUNCTION__, '3.0.0',
			/* translators: %s: misc */
			sprintf( __( 'The "%s" options group has been removed. Use another settings group.' ),
				'misc'
			)
		);
		$option_group = 'general';
	}

	if ( 'privacy' == $option_group ) {
		_deprecated_argument( __FUNCTION__, '3.5.0',
			/* translators: %s: privacy */
			sprintf( __( 'The "%s" options group has been removed. Use another settings group.' ),
				'privacy'
			)
		);
		$option_group = 'reading';
	}

	$pos = array_search( $option_name, (array) $new_whitelist_options[ $option_group ] );
	if ( $pos !== false ) {
		unset( $new_whitelist_options[ $option_group ][ $pos ] );
	}
	if ( '' !== $deprecated ) {
		_deprecated_argument( __FUNCTION__, '4.7.0',
			/* translators: 1: $sanitize_callback, 2: register_setting() */
			sprintf( __( '%1$s is deprecated. The callback from %2$s is used instead.' ),
				'<code>$sanitize_callback</code>',
				'<code>register_setting()</code>'
			)
		);
		remove_filter( "sanitize_option_{$option_name}", $deprecated );
	}

	if ( isset( $wp_registered_settings[ $option_name ] ) ) {
		// Remove the sanitize callback if one was set during registration.
		if ( ! empty( $wp_registered_settings[ $option_name ]['sanitize_callback'] ) ) {
			remove_filter( "sanitize_option_{$option_name}", $wp_registered_settings[ $option_name ]['sanitize_callback'] );
		}

		unset( $wp_registered_settings[ $option_name ] );
	}
}

/**
 * Retrieves an array of registered settings.
 *
 * @since 4.7.0
 *
 * @return array List of registered settings, keyed by option name.
 */
function get_registered_settings() {
	global $wp_registered_settings;

	if ( ! is_array( $wp_registered_settings ) ) {
		return array();
	}

	return $wp_registered_settings;
}

/**
 * Filter the default value for the option.
 *
 * For settings which register a default setting in `register_setting()`, this
 * function is added as a filter to `default_option_{$option}`.
 *
 * @since 4.7.0
 *
 * @param mixed $default Existing default value to return.
 * @param string $option Option name.
 * @param bool $passed_default Was `get_option()` passed a default value?
 * @return mixed Filtered default value.
 */
function filter_default_option( $default, $option, $passed_default ) {
	if ( $passed_default ) {
		return $default;
	}

	$registered = get_registered_settings();
	if ( empty( $registered[ $option ] ) ) {
		return $default;
	}

	return $registered[ $option ]['default'];
}