What are some best practices for utilizing the Singleton pattern in PHP applications to maintain code clarity and reusability?

When using the Singleton pattern in PHP applications, it's important to ensure that only one instance of a class is created and that this instance is globally accessible. To maintain code clarity and reusability, it's recommended to encapsulate the Singleton logic within the class itself and provide a static method to access the instance.

class Singleton {
    private static $instance;

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

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

// Usage
$singletonInstance = Singleton::getInstance();