Inheritance is a way of creating a new class from an existing class.
Syntax:
Class Emp : [base class]
#code
.....
Class Pro (Emp) : [derived/child class]
#code
We can use the methods and attributes of Emp in Pro object.
Also, we can overwrite or add new attributes and methods i Pro class.
Types of Inheritance :
1. Single Inheritance
2. Multiple Inheritance
3. Multi level Interitance
Single Inheritance : occurs when child class inherits only a single parent class.
Base class -----> Derived Class
Multiple Inheritance : occurs when the child class inherits from more thn on parent class
parent 1 ----------->
child
parent2 ----------->
Multi level Inheritance : when a child class becomes a parent for another child class
parent --> child1 -->child2
super() method : is used to access the methods of a super class in the derived class.
super(). --init--() [calls construction of the base class]
class methods : A class method is a method which is bound to the class and not the object of the class.
@classmethod decorator is used to create a class method.
Syntax :
@classmethod
def(cls,p1,p2) :
....
@property decorators
consider the following class
Class Emp :
@property
def name(self) :
return self.ename
if e = Emp() is an object of class emp, we can print (ename) to print the ename/call name() function.
@getters and @setters : the method name with @property decorator is called getter method.
we can define a function + @name setter decorator like below:
@name.setter
def name(self, value) :
self. ename = value
Operator Overloading in Python : Operators in python xcan be overloaded using dunder methods. these methods are called when a given operator is used on the objets.
Operators in python can be overloaded using the follwoing methods :
p1 + p2 --> p1 --add-- (p2)
p1 - p2 --> p1 --sub-- (p2)
p1 * p2 --> p1 --mul-- (p2)
p1 / p2 --> p1 --truediv-- (p2)
p1 // p2 --> p1 --floordiv-- (p2)
other dunder /magic methods in python :
--str--() -> used to set what gets displayed upon calling str(obj)
--len--() -> used to set what gets displayed upon calling --len--() orlen (obj)
Programs :
1. #Inheritance
class Employee:
company = "Google"
def showDetails(self):
print("This is an employee")
class Programmer(Employee):
language = "Python"
# company = "Youtube"
def getLanguage(self):
print(f"The language is {self.language}")
def showDetails(self):
print("This is an programmer")
e = Employee()
e.showDetails()
p = Programmer()
p.showDetails()
print(p.company)
2. #single inheritance
class Employee:
company = "Google"
def showDetails(self):
print("This is an employee")
class Programmer(Employee):
language = "Python"
# company = "Youtube"
def getLanguage(self):
print(f"The language is {self.language}")
def showDetails(self):
print("This is an programmer")
e = Employee()
e.showDetails()
p = Programmer()
p.showDetails()
print(p.company)
3. #Multiple Inheritance
class Freelancer:
company = "Fiverr"
level = 0
def upgradeLevel(self):
self.level = self.level + 1
class Employee:
company = "Visa"
eCode = 120
class Programmer(Freelancer, Employee):
name = "Rohit"
p = Programmer()
p.upgradeLevel()
print(p.company)
4. #Multi Level Inheritance
class Person:
country = "India"
def takeBreath(self):
print("I am breathing...")
class Employee(Person):
company = "Honda"
def getSalary(self):
print(f"Salary is {self.salary}")
def takeBreath(self):
print("I am an Employee so I am luckily breathing..")
class Programmer(Employee):
company = "Fiverr"
def getSalary(self):
print(f"No salary to programmers")
def takeBreath(self):
print("I am a Progarmmer so I am breathing++..")
p = Person()
p.takeBreath()
# print(p.company) # throws an error
e = Employee()
e.takeBreath()
print(e.company)
pr = Programmer()
pr.takeBreath()
print(pr.company)
print(pr.country)
5. #Super Class
class Person:
country = "India"
def __init__(self):
print("Initializing Person...\n")
def takeBreath(self):
print("I am breathing...")
class Employee(Person):
company = "Honda"
def __init__(self):
super().__init__()
print("Initializing Employee...\n")
def getSalary(self):
print(f"Salary is {self.salary}")
def takeBreath(self):
super().takeBreath()
print("I am an Employee so I am luckily breathing..")
class Programmer(Employee):
company = "Fiverr"
def __init__(self):
# super().__init__()
print("Initializing Programmer...\n")
def getSalary(self):
print(f"No salary to programmers")
def takeBreath(self):
super().takeBreath()
print("I am a Progarmmer so I am breathing++..")
# p = Person()
# p.takeBreath()
# e = Employee()
# e.takeBreath()
pr = Programmer()
# pr.takeBreath()
6. #class methods
class Employee:
company = "Camel"
salary = 100
location = "Delhi"
# def changeSalary(self, sal):
# self.__class__.salary = sal
@classmethod
def changeSalary(cls, sal):
cls.salary = sal
e = Employee()
print(e.salary)
e.changeSalary(455)
print(e.salary)
print(Employee.salary)
7. #Property Decorator
class Employee:
company = "Bharat Gas"
salary = 5600
salarybonus = 400
# totalSalary = 6100
@property
def totalSalary(self):
return self.salary + self.salarybonus
@totalSalary.setter
def totalSalary(self, val):
self.salarybonus = val - self.salary
e = Employee()
print(e.totalSalary)
e.totalSalary = 5800
print(e.salary)
print(e.salarybonus)
8. #operator overloading
class Number:
def __init__(self, num):
self.num = num
def __add__(self, num2):
print("Lets add")
return self.num + num2.num
def __mul__(self, num2):
print("Lets multiply")
return self.num * num2.num
n1 = Number(4)
n2 = Number(6)
sum = n1 + n2
mul = n1 * n2
print(sum)
print(mul)
9. #dunder methods
class Number:
def __init__(self, num):
self.num = num
def __add__(self, num2):
print("Lets add")
return self.num + num2.num
def __mul__(self, num2):
print("Lets multiply")
return self.num * num2.num
def __str__(self):
return f"Decimal Number: {self.num}"
def __len__(self):
return 1
n = Number(9)
print(n)
print(len(n))
