Parent-child class member variables of different names: a normal visit, had no effect
Parent-child class member variables with the same name: comply with the principle of proximity
Priority to find a local position, if there is a local position of the variable, the direct use
If not, go to this location to find a class member, if used directly
If this position is not a member of the class, then go find a member location of the parent class, if there is direct use, if not an error