local variable 'juveniles' referenced before assignment

[Alan Robinson]

On Wednesday, 13 January 2016 13:23:04 UTC, Alan Robinson  wrote:
> On Wednesday, 13 January 2016 13:06:11 UTC, Peter Otten  wrote:
> > 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
> 
> that's really helpful I understand what's happening now I just need to work out how to do this loop as I am new it looks difficult to do here goes not too sure what you mean by make sure setGen is invoked on the first iteration?