base on the flexibility and performance.
the current class loader map is not so smart.
I would like to suppose the Zend Framework's solution.
class load base on it class name.
we want to load Zend_Controller_Action
we pass the class name "Zend_Controller_Action" to a function
then it search in the main library eg. libs
libs/zend/controller/action.php will be what we want.