Inheritance not working in PHP

Programming in php: Inheritance not working in PHP on newest questions tagged php – Stack Overflow

I have got this structure:

abstract class Android {
    public function __construct() {

    }

    public abstract function cost();

    public function get_model(){
        return "unkown model";
    }
}

class HTC extends Android {

    public function __construct() {
        parent::__construct();
        $this->model= "HTC";
    }

    public function get_model() {
        return $this->model;
    }

    public function cost() {
        return 500;
    }
}

abstract class FeaturesDecorator extends Android {
    public function __construct() {
        parent::__construct();
    }

    public abstract function get_description();
}

class VideoCamera extends FeaturesDecorator {
    private $android;

    public function __construct($android) {
        parent::__construct();
        $this->android=$android;
    }

    public function get_description() {
         return $this->android->get_model()." plus a video camera, ";
    }

    public function cost() {
        return 200 + $this->android->cost();
    }
}

class BigScreenSize extends FeaturesDecorator {
    private $android;

    public function __construct($android) {
        parent::__construct();
        $this->android=$android;
    }

    public function get_description() {
        return $this->android->get_model()." plus a big size screen, ";
    }

    public function cost() {
        return 100 + $this->android->cost();
    }
}

After applying the following pattern:

$android2 = new HTC();
$android2 = new BigScreenSize($android2);
$android2 = new LongLastingBattery($android2);

echo "<br/><br/>You have bought ".$android2->get_description()." for $".$android2->cost();

I get

You have bought Unkown brand plus a long lasting battery, for $650

Again:

I wonder why I get Unknown brand instead of HTC from get_model() called by get_description(), while $650 is being calculated correctly.

source: http://stackoverflow.com/questions/11511496/inheritance-not-working-in-php
Programming in php: programming-in-php