Book-page-165

<?php

class Storage {
    protected $ip;
}

abstract class Database extends Storage{
    abstract public function connect();
}

abstract class FileSystem extends Storage {
    abstract public function mount();
}

class MySQL extends Database{
    public function connect(){
        echo "<br>Connect to MySQL";
    }
}

class TapeDrive extends FileSystem{
    public function mount(){
        echo "<br>Mount to TapeDrive";
    }
}

$mysql = new MySQL();
$mysql->connect();

$tape = new TapeDrive();
$tape->mount();

?>