Types of Methods
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Explore different types of methods in Python including instance, class, and static methods.
Types of Methods :
In Python, methods are functions defined inside a class.
Instance Method
Class Method
Static Method
Each type serves a different purpose in real-world applications.
1. Instance Method
An instance method is used to access and modify object-specific data (instance variables).
It must use self as the first parameter.➡ Each object has its own copy of instance variables.
Why use Instance Methods?
To work with object data
To represent real-life behaviors
To read or update instance variables
Syntax
class ClassName:
def method_name(self):
# use self.variable
Reading Instance Data
Instance Method to Display Data
This program uses an instance method to access and display object-specific data.
class Student:
def __init__(self, name, age):
self.name = name
self.age = age
def display(self):
print("Name:", self.name)
print("Age:", self.age)
s1 = Student("Riya", 21)
s1.display()Instance Method to Update Data
This example updates object data using an instance method.
class BankAccount:
def __init__(self, balance):
self.balance = balance
def deposit(self, amount):
self.balance += amount
print("Updated Balance:", self.balance)
acc = BankAccount(5000)
acc.deposit(2000)
Key Points (Instance Method)
Uses self
Works with instance variables
Called using object
Most frequently used method type
2. Class Method
A class method works with class-level data (shared by all objects).
It uses cls and is defined using @classmethod.➡ Only one copy of class variables exists.
Why use Class Methods?
To access or update class variables
To define factory methods
To perform operations related to the class as a whole
Syntax
class ClassName:
@classmethod
def method_name(cls):
# use cls.variable
Class Method to Access Class Variable
This example shows how class data is shared across all objects.
class Company:
company_name = "TechSoft"
@classmethod
def show_company(cls):
print("Company Name:", cls.company_name)
Company.show_company()
Class Method to Update Class Data
This example updates a class variable using a class method.
class Employee:
bonus = 5000
@classmethod
def update_bonus(cls, new_bonus):
cls.bonus = new_bonus
Employee.update_bonus(8000)
print("Updated Bonus:", Employee.bonus)
Key Points (Class Method)
Uses cls
Works with class variables
Called using class name
Shared data for all objects
3. Static Method
A static method does not use instance or class data.
It is defined using @staticmethod.➡ Behaves like a normal function but belongs to a class.
Why use Static Methods?
Utility/helper functions
Data validation
Logical grouping of functions
🔹 Syntax
class ClassName:
@staticmethod
def method_name():
# utility logic
Static Method for Calculation
This static method performs addition without using class or object data.
class Calculator:
@staticmethod
def add(a, b):
return a + b
print("Result:", Calculator.add(10, 20))
Static Method for Validation
This example validates age using a static method.
class User:
@staticmethod
def is_valid_age(age):
return age >= 18
print(User.is_valid_age(20))
Key Points (Static Method)
No self or cls
No access to class or instance data
Used for helper logic
Improves code structure
📊 Detailed Comparison Table