Inheritance

Inheritance
1
Inheritance allows to define a subclass that inherits all the methods and
properties from parent class.
The benefits of inheritance are:
1. It represents real-world relationships well.
2. It provides reusability of a code. Don’t have to write the same code
again and again. Can add more features to a class without modifying
it.
3. It is transitive in nature, which means that if class B inherits from
another class A, then all the subclasses of B would automatically
inherit from class A.

Inheritance
2
Different forms of Inheritance:
1. Single inheritance: When a child class inherits from only one parent
class, it is called as single inheritance.
2. Multiple inheritance: When a child class inherits from multiple parent
classes, it is called as multiple inheritance.
3. Multilevel inheritance: When we have child and grand child
relationship.
4. Hierarchical inheritance: More than one derived classes are created
from a single base.
5. Hybrid inheritance: This form combines more than one form of
inheritance. Basically, it is a blend of more than one type of
inheritance.

Single Inheritance
3
class Nature:
def rainbow(self):
print("rainbow have 7 colors")
class List(Nature):
def color(self):
print("green is one of the rainbow colors")
d = List()
d.rainbow()
d.color()
Output
rainbow have 7 colors
green is one of the rainbow colors

Multiple Inheritance
4
class Add:
def Summation(self,a,b):
return a+b;
class Mul:
def Multiplication(self,a,b):
return a*b;
class Calci(Add,Mul):
def Divide(self,a,b):
return a/b;
d = Calci()
print(d.Summation(10,20))
print(d.Multiplication(10,20))
print(d.Divide(10,20))

Multilevel Inheritance
5
class Oldmobile:
def m1(self):
print("normal phone")
class Midmobile(Oldmobile):
def m2(self):
print("better phone")
class Smartmobile(Midmobile):
def m3(self):
print("smartmobile")
d = Smartmobile()
d.m1()
d.m2()
d.m3()
Output
normal phone
better phone
smartmobile

Hierarchical Inheritance
6
class College:
def setData(self,id,name):
self.id=id
self.name=name
def showData(self):
print("Id: ",self.id)
print("Name: ", self.name)
class Cse(College):
def setcsedata(self,id,name,dept):
self.setData(id,name)
self.dept=dept
def showcsedata(self):
self.showData()
print("Department: ", self.dept)

Hierarchical Inheritance
7
class Ece(College):
def setecedata(self,id,name,dept):
self.setData(id,name)
self.dept=dept
def showecedata(self):
self.showData()
print("Department: ", self.dept)
print("CSE DEPT")
c=Cse()
c.setcsedata(5,"iare","computers")
c.showcsedata()
print("nECE DEPT")
e = Ece()
e.setecedata(4, "iare", "electronics")
e.showecedata()

Inheritance
8
class Base(object):
def __init__(self, x):
self.x = x
class Derived(Base):
def __init__(self, x, y):
Base.x = x
self.y = y
def printXY(self):
print(Base.x, self.y)
d = Derived(10, 20)
d.printXY()

Inheritance and polymorphism
9
class India:
def intro(self):
print("There are many states in India.")
def capital(self):
print("each state have a capital")
class Ap(India):
def capital(self):
print("Capital of AP is Amaravati")
class Te(India):
def capital(self):
print("Capital of Te is Hyderabad ")

10
i = India()
a = Ap()
t = Te()
i.intro()
i.capital()
a.intro()
a.capital()
t.intro()
t.capital()

11
There are many states in India.
each state have a capital
Capital of AP is Amaravati
Capital of Te is Hyderabad

Method overriding
12
Method overriding is a concept of object oriented programming that
allows us to change the implementation of a function in the child
class that is defined in the parent class.
Following conditions must be met for overriding a function:
1. Inheritance should be there.
2. The function that is redefined in the child class should have the
same signature as in the parent class i.e. same number of
parameters.

13
class Parent(object):
def __init__(self):
self.value = 5
def get_value(self):
print(self.value)
class Child(Parent):
pass
c=Child()
c.get_value()
Output
5
Method overriding

Method overriding
14
class Parent(object):
def __init__(self):
self.value = 5
print(self.value)
class Child(Parent):
print(self.value + 1)
c=Child()
c.get_value()
Output
6

Method overriding
15
class Robot:
def action(self):
print('Robot action')
class HelloRobot(Robot):
def action(self):
print('Hello world')
r = HelloRobot()
r.action()
Output
Hello world

Method overriding
16
class Square:
def __init__(self, side):
self.side = side
def area(self):
a=self.side * self.side
print(a)
class Cube(Square):
def area(self):
face_area = self.side * self.side
b=face_area * 6
print(b)
c=Cube(2)
c.area()
Output
24

Super ()
17
super() built-in has two major use cases:
•Allows us to avoid using base class explicitly
•Working with Multiple Inheritance
Syntax
super().methodName(args)
OR
super(subClass, instance).method(args)

Super()
18
class Square:
def __init__(self, side):
self.side = side
def area(self):
a=self.side * self.side
print(a)
class Cube(Square):
def area(self):
super().area()
face_area = self.side * self.side
b=face_area * 6
print(b)

Super()
19
c=Cube(2)
c.area()
Output
4
24

Abstract Classes
20
• An abstract method is a method that has declaration but not has any
implementation.
• A class which contains one or more abstract methods is called an
abstract class.
• Abstract classes are not able to instantiated and it needs subclasses to
provide implementations for those abstract methods which are defined in
abstract classes.
•By defining an abstract base class, common Application Program
Interface(API) can be defined for a set of subclasses.
•A method becomes an abstract by decorated it with a
keyword @abstractmethod.

Abstract Classes
21
• An abstract method is a method that has declaration but
not has any implementation.
from abc import ABC
class MyABC(ABC):
pass
OR
from abc import ABCMeta
class MyABC(metaclass=ABCMeta):
pass

Abstract Classes
22
from abc import ABC, abstractmethod
class Polygon(ABC):
@abstractmethod
def noofsides(self):
pass
class Triangle(Polygon):
print("I have 3 sides")
class Pentagon(Polygon):

Abstract Classes
23
class Hexagon(Polygon):
class Quadrilateral(Polygon):

Abstract Classes
24
R = Triangle()
R.noofsides()
K = Quadrilateral()
K.noofsides()
R = Pentagon()
R.noofsides()
K = Hexagon()
K.noofsides()

Abstract Classes
25
Output:
I have 3 sides
I have 4 sides
I have 5 sides
I have 6 sides

Abstract Classes
26
import abc
class AbstractAnimal(object):
__metaclass__ = abc.ABCMeta
@abc.abstractmethod
def walk(self):
''' data '''
@abc.abstractmethod
def talk(self):
''' data '''

Abstract Classes
27
class Duck(AbstractAnimal):
name = ‘ ‘
def __init__(self, name):
print('duck created.')
self.name = name
def walk(self):
print('walks')
def talk(self):
print('quack')

Abstract Classes
28
obj = Duck('duck1')
obj.talk()
obj.walk()
Output:
duck created
walks
quack

Interfaces
29
•In object oriented programming, an interface is a
set of publicly accessible methods on an object
which can be used by other parts of the program
to interact with that object.
•There’s no keyword in Python.

Interfaces
30
import abc
class Sampleinterface(abc.ABC):
@abc.abstractmethod
def fun(self):
pass
class Example(Sampleinterface):
def fun(self):
print("interface example")
c=Example()
c.fun()

Access specifiers
31
In most of the object-oriented languages access
modifiers are used to limit the access to the
variables and functions of a class.
Most of the languages use three types of access
modifiers, they are -
• Private
• Public
• Protected.

Access specifiers
32
Python makes the use of underscores to specify the
access modifier for a specific data member and
member function in a class.
Access Modifier: Public
The members declared as Public are accessible
from outside the Class through an object of the
class.

Access specifiers
33
Access Modifier: Protected
The members declared as Protected are accessible
from outside the class but only in a class derived
from it that is in the child or subclass.
Access Modifier: Private
These members are only accessible from within the
class. No outside Access is allowed.

Access specifiers
34
Access Modifier: Public
No under score - self.name = name
Access Modifier: Protected
Single under score - self._name = name
Access Modifier: Private
Double under score - self.__name = name

Access specifiers
35
class Company:
def __init__(self, name, proj):
self.name = name
self._proj = proj
def show(self):
print(“IT COMPANY”)

Access specifiers
36
class Emp(Company):
def __init__(self, eName, sal, cName, proj):
Company.__init__(self, cName, proj)
self.name = eName
self.__sal = sal
def show_sal(self):
print("The salary of ",self.name," is ",self.__sal,)

Access specifiers
37
c = Company("TCS", "college")
e = Emp("pandu", 9999666, c.name, c._proj)
print("Welcome to ", c.name)
print("Here",e.name,"is working on",e._proj)
e.show_sal()

Inheritance

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Inheritance