How does the use of get_called_class() affect the implementation of the Singleton pattern in PHP?

When implementing the Singleton pattern in PHP, using get_called_class() can help ensure that the correct subclass is instantiated as a Singleton. This is especially useful when working with inheritance and wanting to maintain a single instance of each subclass. By using get_called_class(), the Singleton pattern can be implemented in a more flexible and robust way. 

class Singleton {
    private static $instances = [];

    public static function getInstance() {
        $class = get_called_class();

        if (!isset(self::$instances[$class])) {
            self::$instances[$class] = new $class();
        }

        return self::$instances[$class];
    }

    protected function __construct() {
        // prevent direct instantiation
    }

    private function __clone() {
        // prevent cloning
    }
}

class Subclass1 extends Singleton {
    // additional subclass logic
}

class Subclass2 extends Singleton {
    // additional subclass logic
}

$instance1 = Subclass1::getInstance();
$instance2 = Subclass2::getInstance();

var_dump($instance1 === Subclass1::getInstance()); // true
var_dump($instance2 === Subclass2::getInstance()); // true

Keywords

get_called_class Singleton pattern implementation PHP affect

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