Re: local variable 'juveniles' referenced before assignment

Newsgroups	comp.lang.python
Date	2016-01-13 05:26 -0800
References	<d668ec4e-509e-48a4-9be5-017077629c6c@googlegroups.com> <mailman.99.1452688353.13488.python-list@python.org> <5b66e2de-bc73-4200-a9c1-645d2e3f0467@googlegroups.com> <mailman.102.1452690357.13488.python-list@python.org> <cfe57c30-6fc0-4d8d-bce3-de10116874fa@googlegroups.com>
Message-ID	<8c528328-0dcd-49df-8d0c-d4519f24ea3a@googlegroups.com> (permalink)
Subject	Re: local variable 'juveniles' referenced before assignment
From	Alan Robinson <arobinson@lordlawson.org.uk>

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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@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?

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local variable 'juveniles' referenced before assignment Alan Robinson <arobinson@lordlawson.org.uk> - 2016-01-13 04:23 -0800
  Re: local variable 'juveniles' referenced before assignment Chris Angelico <rosuav@gmail.com> - 2016-01-13 23:32 +1100
    Re: local variable 'juveniles' referenced before assignment Alan Robinson <arobinson@lordlawson.org.uk> - 2016-01-13 04:54 -0800
      Re: local variable 'juveniles' referenced before assignment Chris Angelico <rosuav@gmail.com> - 2016-01-14 00:05 +1100
      Re: local variable 'juveniles' referenced before assignment Peter Otten <__peter__@web.de> - 2016-01-13 14:05 +0100
        Re: local variable 'juveniles' referenced before assignment Alan Robinson <arobinson@lordlawson.org.uk> - 2016-01-13 05:22 -0800
          Re: local variable 'juveniles' referenced before assignment Alan Robinson <arobinson@lordlawson.org.uk> - 2016-01-13 05:26 -0800

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