I need help for the code on Chapter 4 about the Observer Pattern!
Not so many rows but this won't work. Maybe I'm not so an advanced Oop developer with Php5, but I had some problems even using the downloaded code from Wrox 'till now. The past Chapter 3 contact manager application simply won't work anyway, even with the wrox code. I had past Oop experiences with Java and Actionscript2. So I hope the mistakes are in the sintax and not in the logic of the application.
Please Wrox (and Authors): give more support and publish correct code! Books are intended to learn not to drive crazy! Other than that this is really an amazing book for the advanced developer.

Chapter 4 Observer Pattern (useful also for decorator) code:
After 15 minutes I fixed the code this way (changes in bold).

<?php
//OBSERVER PATTERN
//abstract_widget.php
//
interface Observer {
    public function update(Observable $subject);
}
//error in this class
abstract class Widget implements Observer {
    protected $internalData = array();

    abstract public function draw();

    public function update(Observable $subject) {
        $this->internalData = $subject->getData();
    }
}
....
?>

since abstract class Widget implements the Observer interface, its update method should accept the same parameters.
I hope I'll find a fix even for the chapter 3 application...