Object lifecycle overview in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this code involving object creation and deletion?

Consider the following Python code that creates and deletes an object. What will be printed?

Python

class MyClass:
    def __init__(self):
        print('Object created')
    def __del__(self):
        print('Object deleted')

obj = MyClass()
del obj
print('End of program')

A

Object created
End of program
Object deleted

B

Object created
Object deleted
End of program

C

End of program
Object created
Object deleted

D

Object deleted
Object created
End of program

💡 Hint

Think about when __init__ and __del__ methods are called.

The __init__ method runs when the object is created, printing 'Object created'. The del obj statement deletes the object, triggering __del__ and printing 'Object deleted'. Finally, 'End of program' is printed.

🧠 Conceptual

intermediate

When is the __del__ method called in Python?

Choose the correct statement about when Python calls the __del__ method of an object.

A When the object is created

B When the object is about to be destroyed by garbage collection

C When the program starts

D When the object is assigned to a new variable

💡 Hint

Think about object lifetime and memory cleanup.

The __del__ method is called when an object is about to be destroyed, usually when no references to it remain and the garbage collector cleans it up.

❓ Predict Output

advanced

What is the output of this code with multiple references and deletion?

Analyze the code below. What will be printed?

Python

class Demo:
    def __init__(self):
        print('Created')
    def __del__(self):
        print('Deleted')

obj1 = Demo()
obj2 = obj1

del obj1
print('Deleted obj1')
del obj2
print('Deleted obj2')

A

2jbo deteleD
deteleD
1jbo deteleD
detaerC

B

Created
Deleted obj1
Deleted obj2

C

Created
Deleted obj1
Deleted
Deleted obj2

D

Created
Deleted obj1
Deleted obj2
Deleted

💡 Hint

Remember that the object is deleted only when all references are gone.

The object is created and printed 'Created'. Deleting obj1 removes one reference but obj2 still points to the object, so __del__ is not called yet. After deleting obj2, no references remain, so __del__ runs and prints 'Deleted'. The print statements show the order.

🔧 Debug

advanced

Why does this __del__ method not always run?

Look at this code snippet. Sometimes 'Deleted' is not printed. Why?

Python

class Test:
    def __del__(self):
        print('Deleted')

def create():
    obj = Test()

create()
print('Done')

A Because the program ends before garbage collection runs

B Because __del__ is not a valid method name

C Because the object is still referenced and not deleted immediately

D Because the object is never created

💡 Hint

Think about when Python runs garbage collection and program exit behavior.

The object obj is created inside create() and goes out of scope after the function ends. However, Python may delay garbage collection until program exit. Sometimes __del__ is not called before 'Done' is printed because the program ends before cleanup.

🧠 Conceptual

expert

What happens if an exception is raised inside __del__?

Choose the correct statement about exceptions raised inside the __del__ method.

A The exception is caught and logged by Python silently

B The exception is propagated and stops the program immediately

C The exception causes the object to never be deleted

D The exception is ignored and a warning is printed to stderr

💡 Hint

Think about how Python handles errors during object destruction.

If an exception occurs inside __del__, Python does not propagate it. Instead, it prints a warning message to standard error and continues program execution. This prevents program crashes during garbage collection.