class Registry { private static $instance = null; private $data = array(); private function __construct() {} public static function getInstance() { if (self::$instance == null) { self::$instance = new Registry(); } return self::$instance; } public function set($key, $value) { $this->data[$key] = $value; } public function get($key) { if (isset($this->data[$key])) { return $this->data[$key]; } return null; } } // Register database parameters $reg = Registry::getInstance(); $reg->set('db.host', 'localhost'); $reg->set('db.user', 'root'); $reg->set('db.password', 'password'); $reg->set('db.name', 'my_database'); // Access parameters from other parts of the application $host = $reg->get('db.host'); $user = $reg->get('db.user'); $password = $reg->get('db.password'); $name = $reg->get('db.name'); // Use the parameters to create a database connection $conn = mysqli_connect($host, $user, $password, $name);This code example demonstrates how the PHP Registry instance can be used to store and retrieve database connection parameters. We register the parameters with the registry using the set() method and then access them from other parts of the code using the get() method. This simplifies the process of creating database connections throughout the application. The package library for the PHP Registry instance is not applicable as it is a design pattern that can be implemented in any PHP application without requiring any third-party library.