php dynamically create attributes

class Book{  
        public $name;  
        public function __construct($name) {  
                $var=  func_get_arg(0);  
                if(is_int($var)){  
                        $this->name="12345".$name;  
                }  
                if(is_string($name)){  
                          $this->name=$name;  
                }  
                
        }  
          
}  
  
class Main{  
          
        public static  function createbook($class,$config=null){  
                return new $class($config);  
        }  
        public function config($config){  
                if(is_array($config)){  
                        foreach($config  as $key=>$val){  
                                $this->$key=$val;  
                        }  
                }  
        }  
}  
$config=array(  
                         'name'=>'My Web Application',  
);  
$main=new Main();  
$main->config($config);  
  echo  $main->name;