Python Coding challenge - Day 1105| What is the output of the following Python Code?

 

Code Explanation:

1️⃣ Defining a Metaclass

class Meta(type):

Explanation

Meta is a metaclass.

A metaclass is used to control how classes are created.

By default, Python uses type to create classes.

Here, we customize that process.

2️⃣ Overriding __new__

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

Explanation

__new__ is called when a class is being created.

Parameters:

cls → the metaclass (Meta)

name → name of class (A)

bases → parent classes

d → dictionary of class attributes

3️⃣ Modifying Class Attributes

d['x'] = 100

Explanation

Adds a new attribute x to the class.

This happens before the class is actually created.

So every class using this metaclass will have:

x = 100

4️⃣ Creating the Class

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

Explanation

Calls the original type.__new__() method.

Actually creates the class A with updated attributes.

Returns the newly created class.

5️⃣ Defining Class with Metaclass

class A(metaclass=Meta):

Explanation

Class A is created using Meta.

So Meta.__new__() runs automatically.

It injects x = 100 into class A.

6️⃣ Empty Class Body

pass

Explanation

No attributes are defined manually.

But x is already added by the metaclass.

7️⃣ Creating an Object

a = A()

Explanation

Creates an instance a of class A.

Object can access class attributes.

8️⃣ Accessing Attribute

print(a.x)

Explanation

Python looks for x:

In object → not found

In class → found (x = 100)

📤 Final Output

100

Book:  700 Days Python Coding Challenges with Explanation