Python Coding challenge - Day 1063| What is the output of the following Python Code?

 

Code Explanation:

1️⃣ Defining Class A

class A:

Creates a class named A.

All objects created from this class will use its attributes and methods.

🔹 2️⃣ Defining a Class Attribute

x = 10

x is a class variable.

It belongs to the class A, not to individual objects.

Any instance can access it unless overridden.

So internally:

A.x = 10

🔹 3️⃣ Defining __getattr__

def __getattr__(self, name):

    return 99

This method is called only when an attribute is NOT found normally.

Parameters:

self → the object

name → name of the missing attribute

Behavior here:

If an attribute does not exist, return 99.

Example:

a.unknown → 99

🔹 4️⃣ Creating an Object

a = A()

Creates an instance a of class A.

Internally:

a.__dict__ = {}

The object has no instance attributes yet.

🔹 5️⃣ Printing Two Attributes

print(a.x, a.y)

Python evaluates both attributes separately.

🔹 Step 1: Accessing a.x

Python follows attribute lookup order:

1️⃣ Check instance dictionary

a.__dict__

No x found.

2️⃣ Check class attributes

A.x

Found:

10

So Python returns 10.

📌 __getattr__ is NOT called because the attribute exists.

🔹 Step 2: Accessing a.y

Now Python looks for y.

1️⃣ Instance dictionary

❌ Not found

2️⃣ Class dictionary

❌ Not found

3️⃣ Parent classes (MRO)

❌ Not found

Now Python calls:

__getattr__(self, "y")

Inside the method:

return 99

So the result is 99.

✅ Final Output

10 99

900 Days Python Coding Challenges with Explanation