Python Coding challenge - Day 1173| What is the output of the following Python Code?

 

 Code Explanation:

🔹 Step 1: Import cached_property

from functools import cached_property

cached_property is a modern Python feature.

It works like:

@property

but with one important difference:

The value is calculated only once

and then stored (cached).

🔹 Step 2: Create Class

class A:

A new class named A is created.

🔹 Step 3: Define Cached Property

@cached_property

def x(self):

    return []

This creates a property named:

x

When accessed for the first time:

a.x

Python executes:

return []

and stores the result.

🔹 Step 4: Create Object

a = A()

Object created:

a

At this moment:

x has NOT been executed yet

because cached properties are lazy.

🔹 Step 5: Access a.x

a.x.append(1)

Before .append() can run, Python evaluates:

a.x

Since this is the first access:

Python executes:

def x(self):

    return []

Result:

[]

This list is now cached internally.

Memory:

a.x ──► []

🔹 Step 6: Execute Append

Now Python runs:

[].append(1)

List becomes:

[1]

Since the cached object itself was modified:

Memory becomes:

a.x ──► [1]

🔹 Step 7: Print a.x

print(a.x)

Python checks:

Has x already been computed?

✅ Yes

So it does NOT execute:

return []

again.

Instead it returns the cached object:

[1]

🔹 Step 8: Print Result

print([1])

Output:

[1]