/** * 观察者模式 */ class Father{    private $_observers = array();     public function register($sub){ /*  注册观察者 */        $this->_observers[] = $sub;    }          public function trigger(){  /*  外部统一访问    */        if(!empty($this->_observers)){            foreach($this->_observers as $observer){                $observer->update();            }        }    }} /** * 观察者要实现的接口 */interface Observerable{    public function update();} //实际用到时class Subscriber implements Observerable{    public function update(){        echo ‘observers test‘;    }} /** * 之后的任何类，只要继承Father 就可以使用观察者模式 */class sun extends Father{}$test = new sun;$test->register(new Subscriber);$test->trigger();