Understanding Inheritance in Python: A Comprehensive Guide to OOP Concepts

• In Python, every class uses inheritance and is inherited from object by default.

• Hence, the below two definitions of MySubClass are same.

Definition 1

class MySubClass:   
   pass

Definition 2

class MySubClass(object):   
    pass                    

• object is known as parent or super class.

• MySubClass is known as child or subclass or derived class.

class Person:
    def __init__(self, fname, lname):
        self.fname = fname
        self.lname = lname
class Employee(Person):
    all_employees = []
    def __init__(self, fname, lname, empid):
        Person.__init__(self, fname, lname)
        self.empid = empid
        Employee.all_employees.append(self)

• Employee class is derived from Person.

p1 = Person('George', 'smith')
print(p1.fname, '-', p1.lname)
e1 = Employee('Jack', 'simmons', 456342)
e2 = Employee('John', 'williams', 123656)
print(e1.fname, '-', e1.empid)
print(e2.fname, '-', e2.empid)

Output

George - smith
Jack - 456342
John - 123656

• In the above example, Employee class utilizes __init __ method of the parent class Person to create its object.

• Inheritance feature can be also used to extend the built-in classes like list or dict.

• The following example extends list and creates EmployeesList, which can identify employees, having a given search word in their first name.

Example 1

 class EmployeesList(list):
    def search(self, name):
        matching_employees = []
        for employee in Employee.all_employees:
            if name in employee.fname:
                matching_employees.append(employee.fname)
        return matching_employees