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Encapsulation in Python

Theory

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Encapsulation in Python

Encapsulation keeps data with the methods that are allowed to change it. On a bank account, Main should call deposit(100), not poke a.balance = -9. You hide the field with _balance or __balance and expose deposit / get_balance. The object protects its own rules — amount must be > 0.

Dry-run: Account starts at 0. deposit(100) → 100. deposit(-50) ignored. get_balance() prints 100. __balance is not for Main to touch. That is encapsulation for a fresher — not a long OOP essay.

Encapsulation in Python — output — 100. deposit(-50) ignored. __balance is not for Main to poke.

Diagram

Account
    __balance
         │ only via
         ▼
    deposit() / get_balance()

Exam tip

__balance + deposit that rejects negatives.

Example

# Encapsulation
class Account:
    def __init__(self):
        self.__balance = 0
    def deposit(self, amt):
        if amt > 0:
            self.__balance += amt
    def get_balance(self):
        return self.__balance

a = Account()
a.deposit(100)
a.deposit(-50)
print(a.get_balance())

Encapsulation in Python — output: 100. deposit(-50) ignored. __balance is not for Main to poke.

Short notes

DefHide fields. Expose safe methods.
Ruledeposit / get, not a.balance = -9.
Remember__balance name mangling.

# Encapsulation class Account: def __init__(self): self.__balance = 0 def deposit(self, amt): if amt > 0: self.__balance += amt def get_balance(self): return self.__balance a = Account() a.deposit(100) a.deposit(-50) print(a.get_balance())

Encapsulation in Python

Example

Short notes

Questions

Encapsulation in Python

Example

Short notes

Questions