Python Coding challenge - Day 752| What is the output of the following Python Code?

 

Code Explanation:

1. Import the weakref module

import weakref

Imports Python’s weakref library.

A weakref (weak reference) lets you reference an object without increasing its reference count.

This allows Python’s garbage collector to delete the object when no strong references exist.

2. Define a simple class

class A: pass

Creates a minimal class A.

It has no attributes or methods.

Objects of this class can still be created.

3. Create an instance

obj = A()

Creates an object obj of class A.

This is a strong reference, meaning obj keeps the object in memory.

4. Create a weak reference

r = weakref.ref(obj)

Makes a weak reference to obj.

r() can be called like a function to access the original object if it still exists.

But it doesn’t prevent the object from being garbage collected.

5. Check if weakref points to same object

print(r() is obj)

r() retrieves the referenced object.

Since obj still exists, r() is that object.

So this prints:

True

6. Delete the strong reference

del obj

Deletes the strong reference obj.

Now no strong reference to the object exists.

Since only a weak reference remains, the object can be garbage collected.

7. Check if weakref is None

print(r() is None)

After obj is deleted and garbage collected, r() no longer points to the object.

Instead, it returns None.

So this prints:

True

Final Output

True

True

500 Days Python Coding Challenges with Explanation