[New-bugs-announce] [issue36872] passing negative values through modules

[David Collins]

New submission from David Collins <coldy028 at gmail.com>:

program_data.py file contains a list 

import list_function
 
str_list4 = ['i', 't']
str_list4 = list_function.insert_value(str_list4, 's', -1)
print(str_list4)


list_function.py file 

def insert_value(my_list, value, insert_position):
    counter = 0
    print('Question 5')
    print(my_list, value, insert_position)
    for index in my_list:
        counter += 1

when passing the negative number in insert_position between the two modules this causes

 str_list4 = list_function.insert_value(str_list4, 's', -1)

  File "D:\part A\list_function.py", line 85, in insert_value
    for index in my_list:

TypeError: 'NoneType' object is not iterable

my_list now becomes lost, if the negative value is changed to positive this clears up . 

if you assign the -1 to a variable or a contstant it does not matter 
it still causes the same issue. 

however if you are running this code in the same module it works fine. this only seems to appear when attempting to pass between 2 modules a negative number.

----------
assignee: terry.reedy
components: IDLE
messages: 342049
nosy: coldy028, terry.reedy
priority: normal
severity: normal
status: open
title: passing negative values through modules
type: compile error
versions: Python 3.7

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue36872>
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