What is the design pattern used to write this PHP code?

Question

what is the design pattern for this code ?

class Foo {
    private $_connection;
    private static $_instance;
    private $_host = "Host";
    private $_username = "Name";
    private $_password = "encrypted Word";
    private $_database = "Name";

    public static function getInstance() {
        if(self::$_instance = 'Connected') {
            self::$_instance = new self();
        } 

        return self::$_instance;
    }

    private function __construct() {
        $this->_connection = new mysqli($this->_host, $this->_username,
            $this->_password, $this->_database);
    }

    public function getConnection() {
        return $this->_connection;
    }

}

@u_mulder it should be a singleton, but the implementation has bugs.. — Philipp, Jul 16 '18 at 09:21
Possible duplicate of [Creating the Singleton design pattern in PHP5](https://stackoverflow.com/questions/203336/creating-the-singleton-design-pattern-in-php5) — Script47, Jul 16 '18 at 09:21

score 1 · Accepted Answer · answered Jul 16 '18 at 09:33

This should maybe be a singleton, but currently is has bugs and won't work as expected.

The aim of a singleton is, to only have one instance of a class and no possibility to create another one. To achieve this, one creates a static method (getInstance), which stores the instance of the class and lazy instantiates it.

Currently there is a bug

if (self::$instance = 'Contected') ...

First, this isn't a comparison and because of this, the value is always true and each time you call getInstance, you actually create a new one, instead of returning the singleton.

This should be changed to

if (!self::$instance) ...

To get the actual singleton, you simply have to call the getInstance-method.

$foo = Foo::getInstance();

What is the design pattern used to write this PHP code?

1 Answers1