{
protected $observers = [];
public function observe($observer)
{
$this->observers[] = $observer;
}
public function cancelObservation($observer)
{
$i = array_search($observer, $this->observers);
if ($i !== false) {
unset($this->observers[$i]);
}
}
public function notify()
{
foreach ($this->observers as $observer) {
$observer->update($this);
}
}
}
class Observer
{
public function update($project)
{
echo "I heard that this project was updated: \n" . print_r($project, true);
}
}
$project = new Project();
$project->observe(new Observer());
$project->observe(new Observer());
$project->notify();
