php - singleton nasty object, unable to use other objects -

i'm trying use singleton design pattern create object , consume it.

first have system class [the factory] object

system class

class system {          public function require_($file) {                if( file_exists($file) ){                   require( $file ) ;                }else{                   $this -> config_erros['require'][] = $file ;                }         }         public function call($object , $object_name = '') {           if( $object_name == '' ) {            return  $this -> {$object} =  new $object() ;           }else{            return  $this -> {$object_name} =  new $object() ;           }         }          public function __autoload($class , $object_name = '') {                if( is_array( $class ) && !empty( $class ) ) {                   $class = array_unique($class) ;                   foreach( $class $f ) {                      $this -> require_( classes_path . $class .'.php' )  ;                      $this -> call( $class , $object_name ) ;                   }               }else{                   $this -> require_( classes_path . $class .'.php' )  ;                   $this -> call( $class , $object_name ) ;               }         }    } 

i have 3 classes:

mysqly.php   =>    class mysqly files.php    =>    class files image.php    =>    class image 

here calling classes:

$system = new system ; $system -> __auto_load( array('mysqly','files','image') ) ; 

now in system object can use as

$system -> mysqly -> query () ; // call function in mysqly class $system -> files  -> read () ; // call function in files class $system -> image -> query () ; // call function in image class 

as of every thing working fine.

level 2 [ define users module object in system object ]

now want add users class [ users module ] system object

here users class:

class users implements module  {   public function install(){              $system -> mysqly -> exec( '                         create table `users` (                             `id` int(11) not null auto_increment,                             `name` varchar(150)  null,                             `username` varchar(50) not null,                             `password` varchar(32) not null,                             `email` varchar(32) not null,                             `group` int(11) not null,                             `register_date` int(10) not null,                             `last_login` int(10) default null,                             `active_code` varchar(32) not null,                             `reset_code` varchar(32) default null,                             `session_code` varchar(32) default null,                             `status` varchar(2) not null,                              primary key (`id`),                             unique key `email` (`email`),                             key `username` (`username`,`password`,`group`,`status`)                         )                         engine=innodb default charset=utf8      ') ; }  public function uninstall(){}  public function update(){}  public function close(){} } 

i generate this

$system -> require_( module_path.'users.php' ) ; $system -> call ( 'users' ) ; 

this fine want execute users function [ install ]

i can achieve follows:

$system -> users -> install() ; 

here's problem

i want execute mysql query [ use mysqly object on system object ]

but how can execute query depended on mysqly object in system object?

thank you