Python's error handling process includes the finally clause. In the following code snippet, when is the finally clause executed?

inputFile = open("lyrics.txt", "r")
try :
line = inputFile.readline()
words = line.split()
print(words)
finally :
inputFile.close()

Question

Python's error handling process includes the finally clause. In the following code snippet, when is the finally clause executed?

inputFile = open("lyrics.txt", "r")
try :
   line = inputFile.readline()
   words = line.split()
   print(words)
finally :
   inputFile.close()

BlackTom AI · Accepted Answer

To tackle this question, start by identifying where the try/finally structure sits and what it guarantees. 
Option 1: 'The finally clause is never executed in this example.' This would be true only if the code before the try block prevented reaching the finally, or if Python behaved differently; however, the purpose of finally is precisely to run after the try block completes, regardless of whether an exception occurred, provided control reaches the try statement.
Option 2: 'Only when there is an error opening the file.' In this code, the file is opened before entering the try block, so an error opening the file would occur before the try statement is reached. If that happens, the finally block is not involved because control never enters the try/finally construct. Therefore, this statement is inaccurate for this specific arrangement.
Option 3: 'Only when there is an error reading the file.' If an error occurred while reading or processing inside the try block, the finally would still execute to perform cleanup. But saying it runs only on read errors ignores the general contract of finally, which runs after the try block completes (whether or not an exception occurred). This makes the option misleading.
Option 4: 'The finally clause is always executed in this example.' This aligns with Python's semantics: the code inside finally runs after the try block finishes, no matter if an exception was raised in the try block or not, as long as control reaches the finally. In this example, the finally block will always run to close the file, ensuring resource cleanup.
By comparing these, the correct understanding is that the finally clause is designed to execute regardless of exceptions within the try block, and in this particular snippet it will execute after the try block completes (success or error), provided the program reaches the try statement and subsequently the finally block.

Fal25_CS003C_74229 Ch. 7 Pre-Quiz (Remotely Proctored)

Python's error handling process includes the finally clause. In the following code snippet, when is the finally clause executed? inputFile = open("lyrics.txt", "r") try : line = inputFile.readline() words = line.split() print(words) finally : inputFile.close()

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