Python Coding challenge - Day 1043| What is the output of the following Python Code?

Code Explanation:

1. Importing Abstract Class Utilities

from abc import ABC, abstractmethod

Imports tools from Python’s abc (Abstract Base Class) module

ABC → base class used to define abstract classes

abstractmethod → decorator to mark methods that must be implemented by subclasses

🔹 2. Defining an Abstract Base Class A

class A(ABC):

A inherits from ABC

This makes A an abstract class

Abstract classes cannot be instantiated directly

🔹 3. Declaring an Abstract Method

@abstractmethod

def f(self): pass

Declares method f() as abstract

pass means no implementation is provided here

Any subclass of A must implement f() to become concrete

📌 This acts like a contract for subclasses.

🔹 4. Defining Subclass B

class B(A):

B inherits from abstract class A

Python checks whether B provides implementations for all abstract methods

🔹 5. Implementing the Abstract Method Using a Lambda

f = lambda self: "OK"

Assigns a function object to the name f

This counts as implementing the abstract method

Equivalent to:

def f(self):

    return "OK"

📌 Python does not care about syntax, only that a callable named f exists.

🔹 6. Creating an Object of Class B

B()

Allowed because:

All abstract methods (f) are implemented

B is now a concrete class

🔹 7. Calling the Method

print(B().f())

Execution steps:

B() → creates an instance of B

.f() → calls the lambda function

Lambda returns "OK"

print() displays the result

✅ Final Output

OK

400 Days Python Coding Challenges with Explanation