class Config { private static $instance; private $settings = []; private function __construct() { // load config settings $this->settings = [ "database" => [ "host" => "localhost", "username" => "root", "password" => "password", "database" => "mydatabase" ] ]; } public static function getInstance() { if (!self::$instance) { self::$instance = new Config(); } return self::$instance; } public function get($name) { return $this->settings[$name] ?? null; } }In this example, the constructor of the Config class loads the configuration settings from some external source (such as a JSON file or a database). The `getInstance()` method creates a new instance of the Config class if one has not already been created, or returns the existing instance. The `get()` method allows you to retrieve a specific configuration setting by name. The Config Singleton is often used in larger PHP applications, especially those that require a lot of configuration settings. It can be considered as a package library of object-oriented programming.