Exception chaining in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of chained exceptions with raise from

What is the output of this Python code when executed?

Python

def func():
    try:
        x = 1 / 0
    except ZeroDivisionError as e:
        raise ValueError("Invalid value") from e

try:
    func()
except Exception as ex:
    print(type(ex).__name__)
    print(ex)
    print(type(ex.__cause__).__name__)
    print(ex.__cause__)

A

ValueError
Invalid value
ZeroDivisionError
division by zero

B

ZeroDivisionError
division by zero
ValueError
Invalid value

C

ValueError
Invalid value
None
None

D

ZeroDivisionError
Invalid value
ValueError
division by zero

💡 Hint

Remember that 'raise ... from ...' sets the __cause__ attribute of the new exception.

The ValueError is raised from the original ZeroDivisionError. The __cause__ attribute links them, so ex is ValueError and ex.__cause__ is ZeroDivisionError.

❓ Predict Output

intermediate

Effect of exception chaining without 'from'

What will be printed by this code?

Python

try:
    try:
        int('abc')
    except ValueError:
        raise RuntimeError('Conversion failed')
except Exception as e:
    print(type(e).__name__)
    print(e)
    print(e.__cause__)

A

RuntimeError
Conversion failed
ValueError('invalid literal for int() with base 10: \'abc\'')

B

ValueError
invalid literal for int() with base 10: 'abc'
None

C

RuntimeError
Conversion failed
None

D

RuntimeError
Conversion failed
RuntimeError

💡 Hint

Without 'from', the __cause__ attribute is not set automatically.

Raising a new exception without 'from' does not link the original exception as the cause, so __cause__ is None.

🔧 Debug

advanced

Identify the error in exception chaining syntax

Which option contains a syntax error related to exception chaining?

A

try:
    1/0
except ZeroDivisionError as e:
    raise ValueError('Error') from e

B

try:
    1/0
except ZeroDivisionError as e:
    raise ValueError('Error') with e

C

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:e sa rorrEnoisiviDoreZ tpecxe
0/1    
:yrt

D

try:
    1/0
except ZeroDivisionError as e:
    raise ValueError('Error')

💡 Hint

Check the keyword used to chain exceptions.

The keyword 'with' is invalid for exception chaining; the correct keyword is 'from'.

❓ Predict Output

advanced

Output of nested exception chaining with __context__

What will this code print?

Python

def f():
    try:
        int('a')
    except ValueError:
        try:
            1/0
        except ZeroDivisionError:
            raise RuntimeError('Runtime problem')

try:
    f()
except Exception as e:
    print(type(e).__name__)
    print(e)
    print(type(e.__context__).__name__)
    print(e.__context__)

A

ZeroDivisionError
division by zero
ValueError
invalid literal for int() with base 10: 'a'

B

RuntimeError
Runtime problem
ValueError
invalid literal for int() with base 10: 'a'

C

RuntimeError
Runtime problem
None
None

D

RuntimeError
Runtime problem
ZeroDivisionError
division by zero

💡 Hint

When an exception is raised during handling another, __context__ stores the original exception.

The RuntimeError is raised inside the except block for ZeroDivisionError, so __context__ is ZeroDivisionError.

🧠 Conceptual

expert

Understanding implicit vs explicit exception chaining

Which statement best describes the difference between implicit and explicit exception chaining in Python?

A Explicit chaining uses 'raise ... from ...' to set __cause__, while implicit chaining sets __context__ automatically when an exception occurs during handling another.

B Implicit chaining uses 'raise ... from ...' to set __cause__, while explicit chaining sets __context__ automatically.

C Explicit chaining sets __context__ to None, implicit chaining sets __cause__ to None.

D Implicit chaining requires manual assignment of __cause__, explicit chaining happens automatically.

💡 Hint

Think about how Python links exceptions automatically versus when you use 'from'.

Explicit chaining uses 'raise ... from ...' to set __cause__. Implicit chaining happens automatically and sets __context__ when an exception occurs during handling another.