Observer Pattern

    
    
observer.php

    function autoloader($class) {
        $newName = str_replace('\\', '/', $class);
        $path = "lib/$newName.php";

        if (!class_exists($class)) {
            if (file_exists($path)) {
                require $path;
            }
        }
    }
    spl_autoload_register(autoloader);


    ini_set('display_errors', true);

    $alarmAnlage = new \Alarm\System();

    $alarmAnlage->attach(new \Alarm\Observer\Email());
    $alarmAnlage->attach(new \Alarm\Observer\SMS());
    $alarmAnlage->attach(new \Alarm\Observer\Telefon());

    $alarmAnlage->triggerAlert("Klimaanlage ausgefallen");
    

    
lib/Alarm/Observer.php
    namespace Alarm;

    abstract class Observer {
        abstract public function update(System $system);
    }
    

    
lib/Alarm/System.php
    namespace Alarm;

    interface AlarmDispatcher {
        public function attach(Observer $observer);
        public function detach(Observer $observer);
        public function notify();
    }

    class System implements AlarmDispatcher
    {
        private $_alertMsg = "";
        private $_observers = array();

        public function triggerAlert(string $msg)
        {
            $this->_alertMsg = $msg;
            $this->notify();
        }

        public function getAlert() {
            return $this->_alertMsg;
        }

        public function attach(Observer $observer)
        {
            $this->_observers[] = $observer;
        }

        public function detach(Observer $observer)
        {
            foreach ($this->_observers as $index => $currentObserver) {
                if ($observer == $currentObserver) {
                    unset($this->_observers[$index]);
                }
            }
        }

        public function notify()
        {
            foreach ($this->_observers as $observer) {
                $observer->update($this);
            }
        }
    }
    

    
Observer
    
lib/Alarm/Observer/Email.php
    namespace Alarm\Observer;

    use Alarm\Observer;
    use Alarm\System;

    class Email extends Observer {

        public function update(System $system)
        {
            printf("E-Mail Alarm: %s<br>", $system->getAlert());
        }
    }
    

    
lib/Alarm/Observer/SMS.php
    namespace Alarm\Observer;

    use Alarm\Observer;
    use Alarm\System;

    class SMS extends Observer {

        public function update(System $system)
        {
            printf("SMS Alarm: %s<br>", $system->getAlert());
        }
    }
    

    
lib/Alarm/Observer/Telefon.php
    namespace Alarm\Observer;

    use Alarm\Observer;
    use Alarm\System;

    class Telefon extends Observer {

        public function update(System $system)
        {
            printf("Telefonanruf: %s<br>", $system->getAlert());
        }
    }