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Python Python Basics All Together Now Handle Exceptions

Joshua Woodbury
Joshua Woodbury
744 Points

"nesting" valueErrors?

So, I'm following along the best I can. The first ValueError was cancelled out when I added the second. This was best method I could come up with so that both still trigger if needed. It works, but is there an easier way to do this or is this a pretty common solution?

TICKET_PRICE = 10

tickets_remaining = 100  

while tickets_remaining >= 1:
    print("There are {} tickets remaining.".format(tickets_remaining))
    name = input("What's your name?  ")
    num_tickets = input("Ok {}, how many tickets would you like to purchase?  ".format(name))
    try:
        num_tickets = int(num_tickets)
    except ValueError:
        print("Oh no, we ran into an issue. Only numbers are allowed. Please try Again.")
    else:                      
        try:
            if num_tickets > tickets_remaining:
                raise ValueError(f"There are only {tickets_remaining} tickets remaining.")
        except ValueError as err:
            print(f"Oh no, we ran into an issue. {err}. Please try again.")
        else:
            amount_due = num_tickets * TICKET_PRICE
            print(f"Your total is ${amount_due}.")
            should_proceed = input("Do you want to proceed? Y/N?  ")
            if should_proceed.lower() == "y":
                #TODO: Gather credit card info and process it.
                print("Sold!")
                tickets_remaining -= num_tickets
            else:
                print("Thank you for stopping by {}.".format(name))
print("Sorry, the tickets are sold out.")
Thomas Greer
Thomas Greer
1,472 Points

I ran into the same issue. Though, I struggled to resolve it on my own. Your solution fixed my problem, but I do feel there is a cleaner approach. I would love for someone to show their solution.

1 Answer

Steven Parker
Steven Parker
229,921 Points

You don't have to create a nested "try" block to make a test that raises an exception and then catches it. You can just handle your test condition directly as part of the test code body, which is probably a bit more common (and more compactly coded) approach.