[Tutor] How do I fix this IndexError?

[Simon Gerber]

Hi Nathan,

I've attached a crude hack that fixes the problem. It should give you
an idea of how to proceed. I've put comments next to the things I've
changed. Bear in mind I'm hardly more than a beginner myself, so there
are definitely better ways to do this. But it's somewhere to start,
anyway.

Cheers!

[code]

import pickle, os     #LOAD THE OS MODULE

def menu():
    print "1. Change Canadian currency into American."
    print "2. Change American currency into Canadian."
    print "3. Change Canadian currency into Euros."
    print "4. Change Euros into Canadian currency."
    print "5. Update exchange rates."
    print "9. Save and Exit"

def exchange_update():
    print "1. Update Canadian to US rate."
    print "2. Update US to Canadian rate."
    print "3. Update Canadian to Euro rate."
    print "4. Update Euro to Canadian update."
    print "5. Main menu"

def menu_choice():
    return int(raw_input("Which option? "))

print "The Currency Exchange Program"
print "By Nathan Pinno"

if os.path.exists('exch.txt'): # Check to see if 'exch.txt' exists
    store = open('exch.txt', 'rb')  # Only open the file if it exists
    rates = pickle.load(store)    # Save as 'rates', not 'exch'
    store.close()
else:
    # If there's no exch.txt file, use these default rates.
    rates = {'can_us' : 0.80276,
                'us_can' : 1.245702,
                'can_euro' : 1.488707,
                'euro_can' : 0.671724}

while 1:
    menu()
    menu_option = menu_choice()
    if menu_option == 1:
        can = float(raw_input("Canadian $"))
        print "US $",can*rates['can_us']
    elif menu_option == 2:
        us = float(raw_input("US $"))
        print "CAN $",us*rates['us_can']
    elif menu_option == 3:
        can = float(raw_input("CAN $"))
        print "Euros",can*rates['can_euro']
    elif menu_option == 4:
        euro = float(raw_input("Euros"))
        print "CAN $",euro*rates['euro_can']
    elif menu_option == 5:
        while 1:
            exchange_update()
            sub = menu_choice()
            if sub == 1:
                new_can = float(raw_input("New CAN-US Exchange rate: "))
                rates['can_us'] = new_can
                print "Exchange rate successfully updated!"
            elif sub == 2:
                new_us = float(raw_input("New US-CAN Exchange rate: "))
                rates['us_can'] = new_us
                print "Exchange rate successfully updated!"
            elif sub == 3:
                new_cxr = float(raw_input("New CAN-Euro Exchange rate: "))
                rates['can_euro'] = new_cxr
                print "Exchange rate successfully updated!"
            elif sub == 4:
                new_euro = float(raw_input("New Euro-CAN Exchange rate: "))
                rates['euro_can'] = new_euro
                print "Exchange rate successfully updated!"
            elif sub == 5:
                break
    elif menu_option == 9:
        store = open("exch.txt", 'wb') #save
        pickle.dump(rates, store)     # Save 'rates' variable, not 'exch'.
        store.close()
        break
print "Goodbye."


--
Seen in the release notes for ACPI-support 0.34:

'The "I do not wish to discuss it" release
  * Add workaround for prodding fans back into life on resume
  * Add sick evil code for doing sick evil things to sick evil
    screensavers'