When an override needs to keep a superclass’s behavior, call super() instead of replacing that behavior entirely. In a Supervisor.logout method, super().logout() runs the inherited logout implementation before additional supervisor-specific actions. super() also provides access to a superclass constructor when customized initialization is needed. section 8.5.3 section 8.5.6
class Supervisor(Employee):
def logout(self):
super().logout()
print("Additional logout actions for a supervisor")
See the override that calls the superclass logout method before adding a supervisor-specific action. section 8.5.3
Listing 10.10 Creating a custom class for sorting poker cards
class PokerOrder(int):
def __new__(cls, x):
numbers_mapping = {'J': 11, 'Q': 12, 'K': 13, 'A': 14}
casted_number = numbers_mapping.get(x, x)
return super().__new__(PokerOrder, casted_number)
This PokerOrder example uses super().__new__ to construct an int subclass with mapped values for face cards. section 10.5.3
Method resolution order (MRO) determines where Python finds a method or attribute in an inheritance hierarchy. Inspect a class’s MRO when reasoning about which implementation is reached; the basic explanation focuses on a subclass with one superclass. section 8.5.3
