Protected attributes in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of accessing a protected attribute

What is the output of this Python code?

Python

class Car:
    def __init__(self, model):
        self._model = model

car = Car('Tesla')
print(car._model)

A AttributeError

B Tesla

C None

D SyntaxError

💡 Hint

Protected attributes start with a single underscore but can still be accessed directly.

In Python, attributes with a single underscore (e.g., _model) are protected by convention but still accessible directly. So, car._model prints the value 'Tesla'.

❓ Predict Output

intermediate

Accessing protected attribute from subclass

What will this code print?

Python

class Animal:
    def __init__(self):
        self._sound = 'Roar'

class Lion(Animal):
    def make_sound(self):
        return self._sound

lion = Lion()
print(lion.make_sound())

A Roar

B AttributeError

C None

D TypeError

💡 Hint

Protected attributes can be accessed inside subclasses.

The subclass Lion can access the protected attribute _sound from its parent Animal. So, lion.make_sound() returns 'Roar'.

❓ Predict Output

advanced

Effect of name mangling on attribute access

What is the output of this code?

Python

class Secret:
    def __init__(self):
        self.__hidden = 'hidden_value'

s = Secret()
print(hasattr(s, '__hidden'))
print(hasattr(s, '_Secret__hidden'))

A False\nTrue

B True\nFalse

C False\nFalse

D True\nTrue

💡 Hint

Double underscore attributes are name-mangled to include the class name.

Attributes with double underscores are renamed internally to include the class name. So, __hidden becomes _Secret__hidden. The first hasattr returns False, the second True.

🧠 Conceptual

advanced

Understanding protected attribute conventions

Which statement about protected attributes in Python is correct?

A Protected attributes are enforced by Python and cannot be accessed outside the class.

B Protected attributes are the same as private attributes and use double underscores.

C Protected attributes are a naming convention and can be accessed outside the class but should not be.

D Protected attributes are automatically hidden from subclasses.

💡 Hint

Think about what the single underscore means in Python naming.

In Python, a single underscore prefix is a convention to indicate an attribute is protected. It is not enforced by the language, so the attribute can be accessed outside the class but should be treated as non-public.

❓ Predict Output

expert

Output when accessing protected attribute with property

What is the output of this code?

Python

class Box:
    def __init__(self):
        self._content = 'secret'

    @property
    def content(self):
        return self._content

b = Box()
print(b.content)
print(b._content)

A None\nsecret

B secret\nAttributeError

C AttributeError\nsecret

D secret\nsecret

💡 Hint

The property returns the protected attribute, which is also accessible directly.

The property content returns the protected attribute _content. Both b.content and b._content print 'secret'.