To implement a publish/subscribe behaviour to an object, whenever a "Subject" object changes it's state, the attached "Observers" will be notified. It is used to shorten the amount of coupled objects and uses loose coupling instead.
- a message queue system is observed to show the progress of a job in a GUI
PHP already defines two interfaces that can help to implement this pattern: SplObserver and SplSubject.
You can also find these code on GitHub
User.php
User.php
UserObserver.php
UserObserver.php
Tests/ObserverTest.php
Tests/ObserverTest.php