Python Coding challenge - Day 1208| What is the output of the following Python Code?

 

Code Explanation:

🔹 1. Defining the Decorator Function

def deco(cls):

✅ Explanation

A function named deco is created.

It accepts one argument named cls.

Here, cls represents a class object, not a normal variable.

Think of it like this:

Class

↓

Decorator Function

↓

Modify Class

↓

Return Class

Nothing executes yet.

🔹 2. Adding a New Class Attribute

cls.value = 100

✅ Explanation

This line adds a new class variable named value.

Initially, the class has no attributes.

Before:

Test

↓

(No attributes)

After this line executes:

Test

↓

value = 100

This attribute belongs to the class, so every object of this class can access it.

🔹 3. Returning the Modified Class

return cls

✅ Explanation

After modifying the class, the decorator returns it.

Think of it like:

Receive Class

↓

Modify It

↓

Return Updated Class

If you don't return the class, Python would replace the class with None.

🔹 4. Applying the Decorator

@deco

✅ Explanation

This line tells Python:

After creating the class,

send it to

deco()

Python internally converts:

@deco

class Test:

    pass

into:

class Test:

    pass

Test = deco(Test)

This is the most important concept of decorators.

🔹 5. Creating the Class

class Test:

✅ Explanation

Python creates the Test class.

Initially:

Test

↓

Empty Class

It only contains the default attributes provided by Python.

🔹 6. The pass Statement

pass

✅ Explanation

pass means:

Do Nothing

The class has no methods and no variables.

It simply acts as an empty placeholder.

🔹 7. Python Calls the Decorator Automatically

After the class is created, Python automatically executes:

Test = deco(Test)

✅ Explanation

Execution flow:

Create Test Class

↓

Call deco(Test)

↓

Add value = 100

↓

Return Test

↓

Store Back in Test

Now the class becomes:

Test

│

└── value = 100

🔹 8. Accessing the Class Variable

Test.value

✅ Explanation

Python searches for value inside the class.

Current class:

Test

↓

value = 100

Value found:

100

🔹 9. Printing the Value

print(Test.value)

✅ Explanation

Python prints the class variable.

Output:

100

🎯 Final Output

100

Book: 100 Python Challenges to Think Like a Developer