Hackerrank Object-Oriented Programming Basics 5

Question 1

What is the Method Resolution Order (MRO) in Python?

Accepted Answer

The order Python searches classes to find a method when multiple inheritance is used

Answer

MRO defines the hierarchy Python follows (using C3 linearization) to look up methods and attributes across a class inheritance chain.

Question 2

Which dunder method allows objects to be compared with == ?

Accepted Answer

__eq__

Answer

__eq__ is called when == is used; if not defined, Python defaults to identity comparison (same as 'is').

Question 3

What is a mixin in Python OOP?

Accepted Answer

A class that cannot be used as a standalone object and provides reusable methods via multiple inheritance

Answer

A mixin is a class designed to provide methods to other classes through multiple inheritance without being used as a standalone base class.

Question 4

What does __del__ do in Python?

Accepted Answer

Is called when an object is about to be garbage collected

Answer

__del__ is a finalizer called by the garbage collector just before the object is destroyed; it is not a destructor in the C++ sense.

Question 5

How can you check if an object is an instance of a given class or its subclasses?

Accepted Answer

isinstance(obj, ClassName)

Answer

isinstance(obj, ClassName) returns True if obj is an instance of ClassName or any subclass of it, unlike type() which only checks exact type.

(Hackerrank) HackerRank Python Certification Practice Test