<?PHP
    // the global array you want to access
    $GLOBALS['uname'] = array('kernel-name' => 'Linux','kernel-release' => '2.6.27-11-generic','machine' => 'i686');

    // the defined constant used to reference the global var
    define(_SYSTEM_,'uname');

    class Foo {

        // a method where you'd liked to access the global var  
        public function bar() {
            print_r($this->{_SYSTEM_});
        }

        // the magic happens here using PHP5 overloading
        public function __get($d) {
            return $GLOBALS[$d];  
        }

    }

    $foo = new Foo;
    $foo->bar();

?>