Python Coding challenge - Day 690| What is the output of the following Python Code?

 

Code Explanation:

1) Class definition + class variable

class A:

    items = []

items is a class variable (shared by all instances of A).

Only one list object is created and stored on the class A.items.

2) First instance

a1 = A()

Creates an instance a1.

a1.items does not create a new list; it references A.items.

3) Second instance

a2 = A()

Creates another instance a2.

a2.items also references the same list A.items.

4) Mutate through one instance

a1.items.append(10)

You’re mutating the shared list (the class variable), not reassigning.

Since a1.items and a2.items both point to the same list object, the append is visible to both.

5) Observe from the other instance

print(a2.items)

Reads the same shared list; it now contains the appended value.

Output:

[10]

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