Passing Current_User from main app to engine


So i have a general question about passing parameters from the main
application to the engine . So is it a correct approach to inherit the
ApplicationController of the main application in the engine to make use
of the current_user. Since current_user is a strong Rails convention can
we make use of it this way or do we need to have call back functions
from the engine to the main application in order for us to use it ?