Python Coding challenge - Day 1070| What is the output of the following Python Code?

 

Code Explanation:

1. Defining Class D

class D:

Explanation:

This line defines a class named D.

This class will act as a descriptor.

A descriptor is a class that defines methods like __get__, __set__, or __delete__ to control attribute access.

2. Defining __get__ Method

def __get__(self, obj, objtype):

Explanation:

__get__ is a descriptor method.

It is automatically called when the attribute is accessed (read).

Parameters:

self → the descriptor object (D)

obj → the instance of class A

objtype → the class A

Example call when a.x is accessed:

D.__get__(descriptor, a, A)

3. Returning the Value

return obj._x

Explanation:

This returns the value stored in the instance variable _x.

The descriptor redirects access to _x inside the object.

So:

a.x → returns a._x

4. Defining __set__ Method

def __set__(self, obj, value):

Explanation:

__set__ is another descriptor method.

It is automatically called when the attribute is assigned a value.

Example when writing:

a.x = 5

Python internally calls:

D.__set__(descriptor, a, 5)

Parameters:

self → descriptor object

obj → instance of A

value → value being assigned

5. Modifying the Value Before Storing

obj._x = value * 2

Explanation:

Instead of storing the value directly, it multiplies the value by 2.

Then it stores it in obj._x.

So when:

a.x = 5

It becomes:

a._x = 10

6. Defining Class A

class A:

Explanation:

This creates another class named A.

7. Creating Descriptor Attribute

x = D()

Explanation:

Here an object of class D is assigned to attribute x.

This makes x a descriptor attribute.

Any access to x will trigger __get__ or __set__.

So:

A.x → descriptor object of class D

8. Creating an Object

a = A()

Explanation:

This creates an instance a of class A.

9. Assigning Value to x

a.x = 5

Explanation:

Since x is a descriptor, Python calls:

D.__set__(descriptor, a, 5)

Inside __set__:

obj._x = value * 2

So:

a._x = 5 * 2

a._x = 10

10. Accessing x

print(a.x)

Explanation:

Python calls:

D.__get__(descriptor, a, A)

Inside __get__:

return obj._x

Since:

a._x = 10

It returns 10.

11. Final Output

10

500 Days Python Coding Challenges with Explanation