Python Coding challenge - Day 1009| What is the output of the following Python Code?

 

Code Explanation:

1. Defining the descriptor class

class Scale:

This defines a class named Scale.

Objects of this class act as descriptors that control attribute access.

2. Implementing __get__

    def __get__(self, obj, owner):

        return obj.__dict__.get("_x", 1) * 10

__get__ makes Scale a descriptor.

Parameters:

self → the descriptor object (Scale()).

obj → the instance accessing the attribute (i).

owner → the class (Item).

obj.__dict__.get("_x", 1):

Tries to read _x from the instance.

If _x does not exist, it uses default value 1.

The value is then multiplied by 10.

So this descriptor returns a computed value, not a stored one.

3. Defining the owner class

class Item:

This defines a class named Item.

4. Attaching the descriptor

    x = Scale()

x is a class attribute.

It is managed by the Scale descriptor.

Accessing x will trigger Scale.__get__.

5. Creating an instance

i = Item()

An object i of class Item is created.

6. Setting the backing attribute

i._x = 3

_x is a normal instance attribute.

It acts as a backing field used internally by the descriptor.

The descriptor does not store values itself.

7. Accessing the descriptor-managed attribute

print(i.x)

🔍 What happens when i.x is accessed:

Python finds x in the class Item.

x is a descriptor, so Scale.__get__ is called.

obj.__dict__.get("_x", 1) returns 3.

3 * 10 is calculated.

The final value returned is 30.

✅ Final Output

30

700 Days Python Coding Challenges with Explanation