local variable 'juveniles' referenced before assignment

[Peter Otten]

Alan Robinson wrote:

> On Wednesday, 13 January 2016 12:32:51 UTC, Chris Angelico  wrote:
>> On Wed, Jan 13, 2016 at 11:23 PM, Alan Robinson
>> <arobinson at lordlawson.org.uk> wrote:
>> > def menu():
>> >     option = int(input("Please select an option: \n 1: Set Generation 0
>> >     Values \n 2: View Generation 0 Values \n 3: Run Model \n 4: Print
>> >     values"))
>> >
>> >     if option == 1:
>> >         juveniles,adults,seniles = setGen()
>> >     elif option == 2:
>> >         displayGen()
>> >     elif option == 3:
>> >         runModel(juveniles,adults,seniles)
>> >     elif option == 4:
>> >         print(juveniles,adults,seniles)
>> >     menu()
>> >
>> 
>> This is a classic use of recursion instead of iteration. When you call
>> menu() again, you're creating a completely new 'slot' for the new
>> function; it has its own set of names. Assigning to names in one call
>> of menu() has no effect on any other call.
>> 
>> Instead, look into the way a while loop works. You'll find that your
>> code is simpler and clearer, plus your variables will stay set.
>> 
>> ChrisA
> thanks I need the menu to run again not sure how to do that though

def menu():
    option = 1 # make sure setGen is invoked on first iteration
    while option: # choosing 0 ends the while loop
        if option == 1:
           juveniles, adults, seniles = setGen()
        elif option == 2:
           ...
        option = int(input(...)) # choose option for the next iteration