source: polylang/trunk/src/Options/Inactive_Option.php

<?php
/**
 * @package Polylang
 */

namespace WP_Syntex\Polylang\Options;

use WP_Error;
use WP_Syntex\Polylang\Options\Options;

defined( 'ABSPATH' ) || exit;

/**
 * Class defining a decorator for options when Polylang is not active on the current site.
 *
 * @since 3.8
 */
class Inactive_Option extends Abstract_Option {
        public const ERROR_CODE = 'pll_not_active';

        /**
         * The option to decorate.
         *
         * @var Abstract_Option
         */
        private $option;

        /**
         * The key of the option to decorate.
         *
         * @var string
         *
         * @phpstan-var non-falsy-string
         */
        private static $key = 'not-an-option';

        /**
         * Constructor.
         *
         * @since 3.8
         *
         * @param Abstract_Option $option The option to wrap.
         */
        public function __construct( Abstract_Option $option ) {
                $this->option = $option;
                $this->errors = new WP_Error();

                // Make sure the option doesn't contain any value.
                $this->option->reset();
        }

        /**
         * Returns option key.
         *
         * @since 3.8
         *
         * @return string
         *
         * @phpstan-return non-falsy-string
         */
        public static function key(): string {
                return self::$key;
        }

        /**
         * Does nothing except adding an error.
         *
         * @since 3.8
         *
         * @param mixed   $value   Value to set.
         * @param Options $options All options.
         * @return bool True if the value has been assigned. False in case of errors.
         */
        public function set( $value, Options $options ): bool { // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable
                if ( ! in_array( self::ERROR_CODE, $this->errors->get_error_codes(), true ) ) {
                        $this->errors->add(
                                self::ERROR_CODE,
                                /* translators: %s is a blog ID. */
                                sprintf( __( 'Polylang is not active on site %s.', 'polylang' ), (int) get_current_blog_id() )
                        );
                }
                return false;
        }

        /**
         * Returns the value of the option, usually the default value for inactive options.
         *
         * @since 3.8
         *
         * @return mixed
         */
        public function get() {
                return $this->option->get();
        }

        /**
         * Returns an empty schema.
         *
         * @since 3.8
         *
         * @return array The schema.
         */
        public function get_schema(): array {
                return array();
        }

        /**
         * Returns the default value.
         *
         * @since 3.8
         *
         * @return mixed
         */
        protected function get_default() {
                return $this->option->get();
        }

        /**
         * Not used but required by `Abstract_Option`.
         *
         * @since 3.8
         *
         * @return array Partial schema.
         */
        protected function get_data_structure(): array {
                return array();
        }

        /**
         * Not used but required by `Abstract_Option`.
         *
         * @since 3.8
         *
         * @return string
         */
        protected function get_description(): string {
                return '';
        }
}