Python error handling (try + except + finally)

A script will "error out" in two different ways if "something goes wrong":

• silently failing
  • the script continues to run but would yield unexpected or trivial output
• error handling
  • the script stops running and explicitly explains what has happened

To allow flexibility in our Python code, we can use statements that "allow for failure":

• try (to do something)
• except (if it fails, then do something else)
• finally (do some last thing in any case)

The try statement always accompanies an except, while a finally (which must accompany both try and except) remains optional!

Here, we shall look at an example that uses all three:

numbers = [ 'x', 'y', 'z' ]
# this list's values are not actually numbers so the code will "error out" to the except block

try:
  print(x * y * z)
  # multiplies the variables if they are numbers

except:
  print("cannot print because the items are not numbers")
  # if something goes wrong

finally:
  print("thank you for using the app!")
  # shows regardless of the outcome

A finally always executes whether the code goes inside the "try" or the "except" block!