Encapsulation

Concept

Bundle data (attributes) and methods (behaviours) into a single unit (class). It restricts direct access to some of the object’s components, which can prevent the accidental modification of data. Mainly hiding internal state and implementation details.

Type of Encapsulation	Description
Public	Accessible from anywhere, no restrictions.
Protected	Accessible within the class and its subclasses, but not from outside.
Private	Accessible only within the class, not from outside or subclasses.

Data Protection

Prevent direct access to sensitive data.
Validate data before modification.
Maintains data integrity.
Controls how data is accessed and modified.

Code Maintainability

Internal implementation can change without affecting external code.
External interface remains stable.
Reduces dependencies on internal details (Reduces coupling between classes).
Makes code easier to maintain and refactor.

Implementation

Encapsulation can be implemented through private, public, and protected attributes and methods.

Get and Set Methods

bank.py


class BankAccount:
  def __init__(self, owner, balance, pin):
    self.owner = owner # Public attribute
    self._balance = balance  # Protected attribute
    self.__pin = pin  # Private attribute
 
  def get_pin(self):
    return self.__pin
  
  def set_pin(self, pin):
    self.__pin = pin
  
  def deposit(self, amount):
    if amount > 0:
      self._balance += amount
      return True
    return False
 
  def withdraw(self, amount):
    if 0 < amount <= self._balance:
      self._balance -= amount
      return True
    return False
 
  def get_balance(self):
    return self._balance

Property Decorators

You can use property decorators to create getter and setter methods for encapsulated attributes.

bank.py


class BankAccount:
  def __init__(self, username, password, balance, pin):
    self.username = username
    self._balance = balance
    self.__password = password
    self.__pin = pin
 
  @property
  def balance(self):
    return self._balance
 
  @balance.setter
  def balance(self, amount):
    if amount >= 0:
      self._balance = amount
    else:
      raise ValueError("Balance cannot be negative")