Python alter external variable from within function

Question

When I run this it works, but it says

"name 'select_place' is assigned to before global declaration"

When I get rid of the second global, no comment appears, but as select_place is no longer global it is not readable (if selected) in my last line of code. I'm really new to python, ideally I'd like a way of not using the global command but after searching i still can't find anything that helps.

My code:

def attempt(x):
    if location =='a':
         global select_place
         select_place = 0
   if location =='b'
        global select_place
        select_place = 1

place = ([a,b,c,d])

This is the start of some turtle graphics

def Draw_piece_a(Top_right):
    goto(place[select_place])

The best way to avoid global is to avoid global variables. Why not have attempt() explicitly return the value of select_place instead of using a global? — John Coleman
– John Coleman, Commented Sep 1, 2016 at 11:57

Jan · Accepted Answer · 2016-09-01 11:52:58Z

1

You need to declare the variable first, additionally the function code can be made clearer:

select_place = False
def attempt(x):
    global select_place
    if location == 'a':
        select_place = 0
    elif location == 'b':
        select_place = 1

Also, there is no return value for attempt(), is this what you want?

answered Sep 1, 2016 at 11:52

Jan

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