Python Encapsulation

🐍 Python Encapsulation

Encapsulation is an OOP principle that restricts direct access to some attributes and methods of a class.
It protects data and allows controlled access through getter and setter methods.

1️⃣ What is Encapsulation?

Bundling data (attributes) and methods inside a class.
Hiding sensitive data using private variables.
Providing controlled access to attributes.

2️⃣ Access Modifiers in Python

Modifier	How it works	Example
Public	Can be accessed anywhere	`self.name`
Protected (single underscore `_`)	Should not be accessed outside class (convention)	`self._salary`
Private (double underscore `__`)	Cannot be accessed directly outside class	`self.__balance`

3️⃣ Example: Private Variables

class BankAccount:
def __init__(self, owner, balance):
self.owner = owner # public
self.__balance = balance # private

def show_balance(self):
print(f"Balance: {self.__balance}")

b = BankAccount("Vipul", 5000)
print(b.owner) # Vipul
b.show_balance() # Balance: 5000

# print(b.__balance) # ❌ Error: private variable

class BankAccount:

def __init__(self, owner, balance):

self.owner = owner # public

self.__balance = balance # private

def show_balance(self):

print(f"Balance: {self.__balance}")

b = BankAccount("Vipul", 5000)

print(b.owner) # Vipul

b.show_balance() # Balance: 5000

# print(b.__balance) # ❌ Error: private variable

Private variables cannot be accessed directly from outside the class.

4️⃣ Accessing Private Variables (Name Mangling)

Python internally changes __balance to _ClassName__balance:

Direct access is possible but not recommended.

5️⃣ Getter and Setter Methods

Use methods to access or modify private variables safely.

class BankAccount:
def __init__(self, owner, balance):
self.owner = owner
self.__balance = balance

# Getter
def get_balance(self):
return self.__balance

# Setter
def set_balance(self, amount):
if amount >= 0:
self.__balance = amount
else:
print("Balance cannot be negative!")

b = BankAccount("Vipul", 5000)
print(b.get_balance()) # 5000

b.set_balance(7000)
print(b.get_balance()) # 7000

b.set_balance(-100) # Balance cannot be negative!

class BankAccount:

def __init__(self, owner, balance):

self.owner = owner

self.__balance = balance

# Getter

def get_balance(self):

return self.__balance

# Setter

def set_balance(self, amount):

if amount >= 0:

self.__balance = amount

else:

print("Balance cannot be negative!")

b = BankAccount("Vipul", 5000)

print(b.get_balance()) # 5000

b.set_balance(7000)

print(b.get_balance()) # 7000

b.set_balance(-100) # Balance cannot be negative!

6️⃣ Using `@property` Decorator

Python allows getter/setter using decorators:

class Employee:
def __init__(self, name, salary):
self.name = name
self.__salary = salary

@property
def salary(self):
return self.__salary

@salary.setter
def salary(self, value):
if value >= 0:
self.__salary = value
else:
print("Salary cannot be negative!")

e = Employee("Riya", 50000)
print(e.salary) # 50000

e.salary = 60000
print(e.salary) # 60000

e.salary = -100 # Salary cannot be negative!

class Employee:

def __init__(self, name, salary):

self.name = name

self.__salary = salary

@property

def salary(self):

return self.__salary

@salary.setter

def salary(self, value):

if value >= 0:

self.__salary = value

else:

print("Salary cannot be negative!")

e = Employee("Riya", 50000)

print(e.salary) # 50000

e.salary = 60000

print(e.salary) # 60000

e.salary = -100 # Salary cannot be negative!

@property makes your code cleaner and Pythonic.

7️⃣ Summary Table

Feature	Description
Public	Accessible everywhere (`self.name`)
Protected	Single underscore `_var` (convention)
Private	Double underscore `__var` (restricted access)
Getter	Method to get private attribute
Setter	Method to safely set private attribute
`@property`	Pythonic way to create getter/setter

8️⃣ Benefits of Encapsulation

Data protection from accidental modification
Clean and maintainable code
Ability to add validation logic in setter methods
Hides internal implementation details

Python Encapsulation