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          


        

Answer 1

To add to the other answers above, the finally clause executes no matter what whereas the else clause executes only if an exception was not raised.

For example, writing to a file with no exceptions will output the following:

file = open('test.txt', 'w')

try:
    file.write("Testing.")
    print("Writing to file.")
except IOError:
    print("Could not write to file.")
else:
    print("Write successful.")
finally:
    file.close()
    print("File closed.")

OUTPUT:

Writing to file.
Write successful.
File closed.

If there is an exception, the code will output the following, (note that a deliberate error is caused by keeping the file read-only.

file = open('test.txt', 'r')

try:
    file.write("Testing.")
    print("Writing to file.")
except IOError:
    print("Could not write to file.")
else:
    print("Write successful.")
finally:
    file.close()
    print("File closed.")

OUTPUT:

Could not write to file.
File closed.

We can see that the finally clause executes regardless of an exception. Hope this helps.