Python Coding challenge - Day 1004| What is the output of the following Python Code?

 

Code Explanation:

1. Defining the Class

class Cache:

A class named Cache is defined.

It does not define any normal attributes like a, b, etc.

2. Defining __getattr__

    def __getattr__(self, name):

__getattr__ is a special method.

It is called only when an attribute is NOT found in:

the instance (self.__dict__)

the class

parent classes

3. Creating the Missing Attribute

        self.__dict__[name] = 99

A new instance attribute is created dynamically.

The attribute name is whatever was requested (e.g. "a").

The value assigned is 99.

So this line effectively does:

c.a = 99

4. Returning the Value

        return 99

The value 99 is returned.

This becomes the result of the attribute access.

5. Creating an Object

c = Cache()

An instance c of class Cache is created.

Initially:

c.__dict__ == {}

6. First Access: c.a

c.a

Step-by-step:

Python looks for a in c.__dict__ → ❌ not found

Looks in class Cache → ❌ not found

Calls __getattr__(self, "a")

Inside __getattr__:

self.__dict__["a"] = 99

Returns 99

Now:

c.__dict__ == {"a": 99}

7. Second Access: c.a

c.a

Step-by-step:

Python looks for a in c.__dict__

Finds a = 99

__getattr__ is NOT called

Returns 99 directly

8. Printing the Values

print(c.a, c.a)

First c.a → 99 (created via __getattr__)

Second c.a → 99 (read from instance)

9. Final Output

99 99

✅ Final Answer

✔ Output:

99 99

900 Days Python Coding Challenges with Explanation