Question

I just started programming and tried to write something but (of course) it failed. After I while I got to the real problem: The UnboundLocalError. So to save you from all the rubble around I stripped the code down to this:

def test():
    try:
        i1 = int(i1)
        i2 = int(i2)
    except ValueError:
        print "you failed in typing a number"

def input(): 
    i1 = raw_input('please type a number \n >')
    i2 = raw_input('please type a number \n >')

Then I wrote down:

>>>input()
please insert a number
> 3
please insert a number
> 2 
>>>test()

And then I got:

that was not a number
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 7, in test
UnboundLocalError: local variable 'i1' referenced before assignment

How can I solve this in a Pythonic way? Or should I take a whole different way?

Answer 1

The most standard way to do this is to give parameters to your test method :

def test(i1, i2):
    try:
        i1 = int(i1)
        i2 = int(i2)
    except ValueError:
        print "you failed in typing a number"

def input(): 
    i1 = raw_input('please type a number \n >')
    i2 = raw_input('please type a number \n >')
    test(i1, i2)   # here we call directly test() with entered "numbers"

If you really want to test on the interactive prompt, you can do (as suggested in @FerdinandBeyer comment) :

def test(i1, i2):
    try:
        i1 = int(i1)
        i2 = int(i2)
    except ValueError:
        print "you failed in typing a number"
    return i1, i2
    
def input(): 
    i1 = raw_input('please type a number \n >')
    i2 = raw_input('please type a number \n >')
    return i1, i2

And then, on prompt :

>>>var1, var2 = input()
please insert a number
> 3
please insert a number
> 2 
>>>test(var1, var2)