Python Coding challenge - Day 1008| What is the output of the following Python Code?

 

Code Explanation:

1. Defining the descriptor class

class D:

This defines a class D.

Objects of this class will be used as descriptors.

2. Defining __get__

    def __get__(self, obj, owner):

        return "desc"

__get__ makes D a descriptor.

Parameters:

self → the descriptor object (D()).

obj → the instance accessing the attribute (b).

owner → the class of the instance (Box).

Whenever this descriptor is used to access an attribute, it returns "desc".

Since D defines only __get__, it is a non-data descriptor.

3. Defining another class

class Box:

This defines a class named Box.

4. Attaching the descriptor to the class

    x = D()

x is a class attribute.

It is assigned an instance of D, so x becomes a descriptor-managed attribute.

5. Creating an instance

b = Box()

This creates an object b of class Box.

6. Manually adding an instance attribute

b.__dict__["x"] = "inst"

This directly inserts "x": "inst" into the instance’s namespace.

Now b has its own instance attribute x.

This bypasses normal attribute assignment syntax.

7. Accessing the attribute

print(b.x)

Let’s see how Python resolves b.x:

Attribute lookup order (important here)

Data descriptors (have __get__ + __set__)

Instance attributes (b.__dict__)

Non-data descriptors (only __get__)

Class attributes

D is a non-data descriptor (only __get__).

Python checks b.__dict__ before non-data descriptors.

b.__dict__ contains:

{"x": "inst"}

So "inst" is returned.

The descriptor’s __get__ is not called.

✅ Final Output

inst

900 Days Python Coding Challenges with Explanation