Successful withdrawal
Input
withdraw_and_get_balance(100, 30)
Output
70.0
Withdrawing 30 from 100 leaves 70.
Full lesson preview
Use a Protected Attribute in a Subclass
Practice accessing and updating a protected attribute from a subclass to implement behavior.
Python practice9 minEncapsulation & Access PatternsBeginnerLast updated April 8, 2026
Problem statement
You have a base class BankAccount that stores an account balance in a protected attribute _balance and provides deposit functionality. Implement a subclass SavingsAccount that exposes a withdraw(amount) method which:
- Attempts to subtract amount from the protected _balance.
- If amount is greater than the available balance, do not change the balance and return False.
- If the withdrawal is successful, subtract the amount and return True.
Also ensure the public balance property returns the current balance rounded to 2 decimal places. Provide small helper functions so tests can create accounts, perform operations, and inspect balances.
Task
Implement a SavingsAccount subclass that uses a protected _balance attribute from the base BankAccount to perform withdrawals safely.
Examples
Input format
Use provided helper functions such as withdraw_and_get_balance(initial_balance, amount).
Output format
Functions return numeric balances or booleans; tests compare their string representations.
Constraints
- Use the protected attribute convention (_balance) in the base class and have the subclass directly access it.
- balance property returns rounded value to 2 decimal places.
- withdraw returns a boolean indicating success.
Samples
Sample 1
Input
withdraw_and_get_balance(50, 60)
Output
50.0
Attempting to withdraw more than the balance fails and leaves balance unchanged.