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Inheritance offers a mechanism to achieve two aims:
Consider the example of a modelling a university system that contains two types of person: Lecturer and Student.
These two types would share common attributes such as name & age so duplicating these fields in each class is not ideal.
Instead the Person class can be “shared” between the Lecturer and
Student classes by setting it as super class:
class Person(object):
name = None
age = None
def __init__(self, name, age):
self.name = name
self.age = age
#-----------------------------------
class Student(Person): # Person becomes a super class of Student
lectures = None
def __init__(self, name, age, lectures):
# Basically calls Person.__init__(self, name, age)
super(Student, self).__init__(name, age)
self.lectures = lectures
#-----------------------------------
class Lecturer(Person):
salary = None
def __init__(self, name, age, salary):
super(Lecturer, self).__init__(name, age)
self.salary = salary
#-----------------------------------
# Demo
person1 = Student('Bob', 20, ['science', 'maths'])
person2 = Lecturer('Alice', 40, 28000)
# No parentheses required if accessing attribute
print('Student name: ' + person1.name)
print( 'Lecturer name: ' + person2.name)
print('Student lectures: ' + str(person1.lectures))
#print('Lecturer lectures: ' + str(person2.lectures)) => causes AttributeError
print('Lecturer salary: ' + str(person2.salary))
#print('Student salary: ' + str(person1.salary)) => causes AttributeError