namespaceIntro.php

<?php 

namespace com\rsumilang\common; 

class Object { 
   // ... code ... 
} 

?>

<?php 

class String extends com\rsumilang\common\Object { 
   // ... code ... 
} 

?>

<?php

namespace com\rsumilang\common; 

class String extends Object { 
   // ... code ... 
} 

?>

<?php

namespace com\rsumilang\util; 
use com\rsumlang\common as Common; 

class String extends Common\Object { 
   // ... code ... 
}