Purpose of encapsulation in Python - Mini Project: Build & Apply

Understanding the Purpose of Encapsulation in Python

📖 Scenario: Imagine you are creating a simple bank account system. You want to keep the account balance safe so that no one can change it directly by mistake. Instead, you want to control how the balance is changed using special methods.

🎯 Goal: Build a Python class that shows how encapsulation protects the account balance by making it private and allowing controlled access through methods.

📋 What You'll Learn

Create a class called BankAccount with a private variable __balance set to 1000

Add a method deposit that adds money to __balance

Add a method withdraw that subtracts money from __balance only if there is enough balance

Add a method get_balance that returns the current __balance

Show that direct access to __balance is not allowed

💡 Why This Matters

🌍 Real World

Encapsulation is used in real bank software to protect account balances and prevent unauthorized changes.

💼 Career

Understanding encapsulation is important for writing safe and reliable code in software development jobs.

1

Create the BankAccount class with a private balance

Create a class called BankAccount with a private variable __balance set to 1000 inside the __init__ method.

Python

class BankAccount:
    def __init__(self):
        # Your code here

Need a hint?

Use self.__balance = 1000 inside the __init__ method to make the balance private.

2

Add deposit and withdraw methods

Add a method called deposit that takes amount and adds it to self.__balance. Add another method called withdraw that takes amount and subtracts it from self.__balance only if self.__balance is greater than or equal to amount.

Python

class BankAccount:
    def __init__(self):
        self.__balance = 1000

    # Your code here

Need a hint?

Use self.__balance += amount in deposit and check balance before subtracting in withdraw.

3

Add a method to get the current balance

Add a method called get_balance that returns the value of self.__balance.

Python

class BankAccount:
    def __init__(self):
        self.__balance = 1000

    def deposit(self, amount):
        self.__balance += amount

    def withdraw(self, amount):
        if self.__balance >= amount:
            self.__balance -= amount

    # Your code here

Need a hint?

Return the private variable self.__balance in the get_balance method.

4

Show encapsulation by using the class and printing the balance

Create an object called account from BankAccount. Use deposit(500) and withdraw(200) methods on account. Then print the balance using print(account.get_balance()). Also, try to print account.__balance to show it is not accessible.

Python

class BankAccount:
    def __init__(self):
        self.__balance = 1000

    def deposit(self, amount):
        self.__balance += amount

    def withdraw(self, amount):
        if self.__balance >= amount:
            self.__balance -= amount

    def get_balance(self):
        return self.__balance

# Your code here

Need a hint?

Use the methods to change balance and print it. Accessing __balance directly should cause an error.