Types of Methods

Inside python class 3 types of methods are allowed

Instance methods
Class methods
Static methods

Instance Methods

Inside method implementation if we are using instance variables then such type of methods are called instance methods.
Inside instance method declaration we have to pass self variable. def m1(self):
By using self variable inside method we can able to access instance variables.
Within the class we can call instance method by using self variable and from outside of the class we can call by using object reference.

Example

Python

class Student: 
def __init__(self,name,marks): 
self.name=name 
self.marks=marks 
def display(self): 
print('Hi',self.name)
print('Your Marks are:',self.marks) 
def grade(self): 
if self.marks>=60: 
print('You got First Grade') 
elif self.marks>=50: 
print('Yout got Second Grade') 
elif self.marks>=35: 
print('You got Third Grade') 
else: 
print('You are Failed') 
n=int(input('Enter number of students:')) 
for i in range(n): 
name=input('Enter Name:') 
marks=int(input('Enter Marks:')) 
s= Student(name,marks) 
s.display() 
s.grade() 
print()

Output

PowerShell

D:\durga_classes>py test.py
Enter number of students:2
Enter Name:Durga
Enter Marks:90
Hi Durga
Your Marks are: 90
You got First Grade
Enter Name:Ravi
Enter Marks:12
Hi Ravi
Your Marks are: 12
You are Failed

Setter and Getter Methods

We can set and get the values of instance variables by using getter and setter methods.

Setter Method

setter methods can be used to set values to the instance variables. setter methods also known as mutator methods.

syntax

Python

def setVariable(self,variable):
 self.variable=variable

Example

Python

def setName(self,name):
 self.name=name

Output

PowerShell

Getter Method

Getter methods can be used to get values of the instance variables. Getter methods also known as accessor methods.

syntax

Python

def getVariable(self):
 return self.variable

Example

Python

def getName(self):
 return self.name

Output

PowerShell

Example

Python

class Student: 
def setName(self,name): 
self.name=name 
 
def getName(self): 
return self.name 
 
def setMarks(self,marks): 
self.marks=marks 
 
def getMarks(self): 
return self.marks 
 
n=int(input('Enter number of students:')) 
for i in range(n): 
s=Student() 
name=input('Enter Name:') 
s.setName(name) 
marks=int(input('Enter Marks:')) 
s.setMarks(marks) 
 
print('Hi',s.getName()) 
print('Your Marks are:',s.getMarks()) 
print()

Output

PowerShell

D:\python_classes>py test.py
Enter number of students:2
Enter Name:Durga
Enter Marks:100
Hi Durga
Your Marks are: 100
Enter Name:Ravi
Enter Marks:80
Hi Ravi
Your Marks are: 80

Class Methods

Inside method implementation if we are using only class variables (static variables), then such type of methods we should declare as class method.
We can declare class method explicitly by using @classmethod decorator.
For class method we should provide cls variable at the time of declaration.
We can call classmethod by using classname or object reference variable.

Example

Python

class Animal: 
legs=4 
@classmethod 
def walk(cls,name): 
print('{} walks with {} legs...'.format(name,cls.legs)) 
Animal.walk('Dog') 
Animal.walk('Cat')

Output

PowerShell

D:\python_classes>py test.py
Dog walks with 4 legs...
Cat walks with 4 legs...

Program to track the number of objects created for a class

Example

Python

class Test: 
count=0 
def __init__(self): 
Test.count =Test.count+1 
@classmethod 
def noOfObjects(cls): 
print('The number of objects created for test class:',cls.count)
 
t1=Test() 
t2=Test() 
Test.noOfObjects() 
t3=Test() 
t4=Test() 
t5=Test() 
Test.noOfObjects()

Output

PowerShell

Static Methods

In general these methods are general utility methods.
Inside these methods we won’t use any instance or class variables.
Here we won’t provide self or cls arguments at the time of declaration.
We can declare static method explicitly by using @staticmethod decorator.
We can access static methods by using classname or object reference.

Example

Python

class DurgaMath: 
 
@staticmethod 
def add(x,y): 
print('The Sum:',x+y) 
 
@staticmethod 
def product(x,y): 
print('The Product:',x*y) 
 
@staticmethod 
def average(x,y): 
print('The average:',(x+y)/2) 
 
DurgaMath.add(10,20) 
DurgaMath.product(10,20) 
DurgaMath.average(10,20)

Output

PowerShell

The Sum: 30
The Product: 200
The average: 15.0

Note

In general we can use only instance and static methods.Inside static method we can access
class level variables by using class name.
class methods are most rarely used methods in python.

Passing members of one class to another class

We can access members of one class inside another class.

Example

Python

class Employee: 
def __init__(self,eno,ename,esal): 
self.eno=eno 
self.ename=ename 
self.esal=esal 
def display(self): 
print('Employee Number:',self.eno) 
print('Employee Name:',self.ename) 
print('Employee Salary:',self.esal) 
class Test: 
def modify(emp): 
emp.esal=emp.esal+10000 
emp.display() 
e=Employee(100,'Durga',10000) 
Test.modify(e)

Output

PowerShell

D:\python_classes>py test.py
Employee Number: 100
Employee Name: Durga
Employee Salary: 20000
In the above application, Employee class members are available to Test class.

Ungraded Questions

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