Question

On some opensource codes, why do they make use of:

$router = Cfw_Router::getInstance();

Instead of just using

$rounter = new Cfw_Router();

Does it have advantages?

---

getInstance():

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

Answer 1

They’re making use of the singleton pattern. Basically, it allows only one instance to exist at any given time. However, it can sometimes be used to provide a global variable, which is not always the best thing in a design (see the criticisms in the link above).