Getter and setter methods in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of getter method usage

What is the output of this Python code using a getter method?

Python

class Person:
    def __init__(self, name):
        self._name = name
    
    @property
    def name(self):
        return self._name

p = Person("Alice")
print(p.name)

A TypeError

B None

C AttributeError

D Alice

💡 Hint

Look at how the @property decorator allows access to the private variable.

The @property decorator makes the method 'name' act like an attribute. So, p.name returns the value of _name, which is 'Alice'.

❓ Predict Output

intermediate

Output after setting a value with setter

What will be printed after running this code that uses a setter method?

Python

class Temperature:
    def __init__(self, celsius):
        self._celsius = celsius
    
    @property
    def celsius(self):
        return self._celsius
    
    @celsius.setter
    def celsius(self, value):
        if value < -273.15:
            raise ValueError("Temperature below absolute zero!")
        self._celsius = value

t = Temperature(25)
t.celsius = 30
print(t.celsius)

A 30

B 25

C ValueError

D AttributeError

💡 Hint

The setter updates the private variable if the value is valid.

The setter method changes _celsius to 30 because 30 is above absolute zero. So, printing t.celsius shows 30.

❓ Predict Output

advanced

What error is raised when setting invalid value?

What error does this code raise when trying to set an invalid temperature?

Python

class Temperature:
    def __init__(self, celsius):
        self._celsius = celsius
    
    @property
    def celsius(self):
        return self._celsius
    
    @celsius.setter
    def celsius(self, value):
        if value < -273.15:
            raise ValueError("Temperature below absolute zero!")
        self._celsius = value

t = Temperature(20)
t.celsius = -300

A No error

B TypeError

C ValueError

D AttributeError

💡 Hint

Check the condition inside the setter method.

The setter raises a ValueError because -300 is less than -273.15, which is not allowed.

🧠 Conceptual

advanced

Why use getter and setter methods?

Which of these is the main reason to use getter and setter methods in Python classes?

A To control access and validation when getting or setting an attribute

B To make code run faster

C To avoid using classes altogether

D To automatically print attribute values

💡 Hint

Think about why you might want to check or change a value before saving it.

Getters and setters let you control how attributes are accessed or changed, such as adding checks or calculations.

❓ Predict Output

expert

Output of complex getter and setter interaction

What is the output of this code that uses both getter and setter with extra logic?

Python

class BankAccount:
    def __init__(self):
        self._balance = 0
    
    @property
    def balance(self):
        return self._balance
    
    @balance.setter
    def balance(self, amount):
        if amount < 0:
            print("Cannot set negative balance")
        else:
            self._balance = amount

account = BankAccount()
account.balance = 100
print(account.balance)
account.balance = -50
print(account.balance)

A

100
-50

B

100
Cannot set negative balance
100

C

Cannot set negative balance
-50

D

100
100

💡 Hint

Notice what happens when trying to set a negative balance.

The setter prints a warning and does not change _balance if the amount is negative. So balance stays 100 after the failed set.