<?php 
class Senior { 

} 

class Junior extends Senior { 

} 
?> 

<?php 
class Dao { 
    function getSomething() { 

    } 
} 

class Model { 
    var $dao; 
    function Model (& $dao) { 
        $this->dao=& $dao; 
    } 

    function doSomething () { 
        $this->dao->getSomething(); 
    } 
} 

$dao=new Dao; 

$model=new Model($dao); 
$model->doSomething(); 
?> 

<?php 
class LinkWidget { 
    function Display () { 
   
    } 
} 

class View { 
    var $linkWidget; 
    var $page; 
    function View () { 
        $this->linkWidget=new LinkWidget; 
    } 

    function renderPage () { 
        $this->page=$this->linkWidget->display() 
    } 
} 
?> 

<?php 
class HtmlUtils { 
    function unHtmlEntities ($str) { 
        $trans_tbl = get_html_translation_table (HTML_ENTITIES); 
        $trans_tbl = array_flip ($trans_tbl); 
        return strtr ($str, $trans_tbl); 
    } 
} 

class View { 
    function renderPage { 
        $text=HtmlUtils::unHtmlEntities($text); 
    } 
} 
?> 

<?php 
class Debug { 
    function display () { 
        echo ($this->errorMsg); 
    } 
} 

class SomeClass { 
    var $errorMsg='This is an error message'; 
    function someFunction () { 
        if ( DEBUG == 1 ) { 
            Debug::display(); 
        } 
    } 
} 

define ('DEBUG',1); 
$someClass= &new SomeClass; 
$someClass->someFunction(); 
?>