How can the Singleton design pattern be implemented in PHP to ensure a single instance of a class is used throughout the application?

The Singleton design pattern ensures that only one instance of a class is created and used throughout the application. This can be implemented in PHP by creating a private static property to hold the single instance of the class, a private constructor to prevent external instantiation, and a static method to provide access to the single instance. 

class Singleton {
    private static $instance;

    private function __construct() {
        // private constructor to prevent external instantiation
    }

    public static function getInstance() {
        if (self::$instance === null) {
            self::$instance = new self();
        }

        return self::$instance;
    }
}

Keywords

Singleton design pattern PHP class instance application

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