Object-Oriented Programming Basics Flashcards

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

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

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

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

Answer: __eq__

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

What is a mixin in Python OOP?

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

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

What does __del__ do in Python?

Answer: Is called when an object is about to be garbage collected

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

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

Answer: isinstance(obj, ClassName)

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

What is the difference between issubclass() and isinstance()?

Answer: issubclass() checks class-to-class relationship; isinstance() checks object-to-class relationship

issubclass(Child, Parent) checks if a class inherits from another; isinstance(obj, Class) checks if an object is an instance of a class (or subclass).

What will this code output? class Counter: count = 0 def __init__(self): Counter.count += 1 a = Counter() b = Counter() print(Counter.count)

Answer: 2

Each instantiation increments the class attribute Counter.count; after two objects are created, it equals 2.