Python Coding challenge - Day 1136| What is the output of the following Python Code?

 

Code Explanation:

🔹 1. Metaclass Definition

class Meta(type):

    def __new__(cls, name, bases, dct):

        dct['x'] = 100

        return super().__new__(cls, name, bases, dct)

Meta is a metaclass (inherits from type)

__new__ runs when a class is being created, not an object

It receives the class attributes in dct

It modifies the class dictionary by setting:

x = 100

🔹 2. Class Creation (A)

class A(metaclass=Meta):

    x = 10

Python sends this class definition to the metaclass

Internally:

Meta.__new__(Meta, 'A', (), {'x': 10})

The metaclass changes:

{'x': 10} → {'x': 100}

🔹 3. Final Class Structure

After metaclass processing, class A becomes:

class A:

    x = 100

The original x = 10 is overwritten

🔹 4. Object Creation

obj = A()

Creates an instance of class A

obj itself has no x attribute

🔹 5. Attribute Lookup

print(obj.x)

Python checks:

obj → not found

class A → finds x = 100

🔹 ✅ Final Output

100

Book:  500 Days Python Coding Challenges with Explanation