namespaces

php52.php

<?php

 // Google/Client.php
 class Google_Client
 {
     
 }
 
 // Google/Service/Drive.php
 class Google_Service_Drive
 {
     
 }
 
 // Google/Service/Calendar.php
 class Google_Service_Calendar
 {
     
 }

php53.php

<?php

// Arquivo Google/Service/Calendar
namespace Google\Service;

use Google\Client; // A classe está no arquivo Google/Client.php;

class Calendar
{
    private $client;
    
    public function __construct(Client $client)
    {
        $this->client = $client;
    }
}