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I would be very grateful if someone could help explain the reason why I'm struggling with the importing of modules...

I'm using Pythonista to learn OOP and I'm working through a tutorial which centres around the creation of a roulette simulator.

The tutorial emphasis the use of unit testing.

Here is my unit test code which is causing me the problem:

import unittest
from outcome import Outcome
from wheel import Wheel
from non_random import NonRandom


class WheelBuilderTestCase(unittest.TestCase):

    def setUp(self):
        self.five = Outcome("00-0-1-2-3", 6)
        self.zero = Outcome("0", 35)
        self.zerozero = Outcome("00", 35)
        rng = NonRandom(0, 1)
        rng.set_seed(5);
        self.wheel = Wheel(rng)

    def testWheelConstruction(self):
        pass

if __name__ == '__main__':
    unittest.main()

Here is the outcome module:

class Outcome (object):

    def __init__(self, name, odds):
        self.name = name
        self.odds = odds

    def winAmount(self, amount):
        return ( self.odds * amount )

    def __eq__(self, other):
        return ( self.name == other.name )

    def __ne__(self, other):
        return not self.__eq__(other)

    def __str__(self):
        return "%s (%d:1)" % ( self.name, self.odds )

Here is the bin module:

class Bin (object):

    def __init__(self, *outcomes):
        self.outcomes = frozenset(outcomes)

    def add(self, outcome):
        self.outcomes |= set( [outcome] )

    def __str__(self):
        return ', '.join( map(str, self.outcomes) )

and here is the wheel module:

from bin import Bin

class Wheel (object):

    def __init__(self, rng):
        self.rng = rng
        self.bins = tuple(Bin() for i in range(38))

    def addOutcome(self, number, outcome):
        self.bins[number].add(outcome)

    def next(self):
        return rng.choice(self.bins)

    def get(self, bin):
        return self.bins[bin]

However when I run the unit test wheel_test.py I get the following error:

E
======================================================================
ERROR: testWheelConstruction (__main__.WheelBuilderTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/var/mobile/Applications/B3FDE480-BD57-442B-BAA6-D0F3CF220D07/Documents/roulette/wheel_test.py", line 21, in testWheelConstruction
    self.wheel = Wheel(2)
  File "./wheel.py", line 7, in __init__
    self.rng = rng
  File "./wheel.py", line 7, in <genexpr>
    self.rng = rng
NameError: global name 'Bin' is not defined

----------------------------------------------------------------------
Ran 1 test in 0.001s

FAILED (errors=1)
EXIT (1)

It appears that the Bin class isn't defined in the WheelBuilderTestCase even though I imported the Wheel class from the wheel module which does include the import of the Bin class via the bin module.

The bizarre thing is that this works fine in IDLE.

Any thoughts..?

You did not provide us the code for non_random.py.

The problem here is that Apple forces there to be only one Python process in Pythonista. See @omz's explanation at: http://omz-forums.appspot.com/pythonista/post/5771894208856064

These lines at the top of your program might help:

import outcome    ; reload(outcome)
import wheel      ; reload(wheel)
import non_random ; reload(non_random)

This forces the imports to be reloaded. In modules that you will be editing, I would recommend using the import module syntax instead of from module import class when working with Pythonista.