exception handling - Why do we need the "finally" clause in Python?

Question

I am not sure why we need finally in try...except...finally statements. In my opinion, this code block

try:
    run_code1()
except TypeError:
    run_code2()
other_code()

is the same with this one using finally:

try:
    run_code1()
except TypeError:
    run_code2()
finally:
    other_code()

Am I missing something?

Answer 1

It makes a difference if you return early:

try:
    run_code1()
except TypeError:
    run_code2()
    return None   # The finally block is run before the method returns
finally:
    other_code()

Compare to this:

try:
    run_code1()
except TypeError:
    run_code2()
    return None   

other_code()  # This doesn't get run if there's an exception.

Other situations that can cause differences:

• If an exception is thrown inside the except block.
• If an exception is thrown in run_code1() but it's not a TypeError.
• Other control flow statements such as continue and break statements.