Question

I am a newbie to python.I am trying to access a variable defined inside main() in a module which is being imported in the main function. I want a method to get this withput passing the deviceid variable to get_a()
main.py:-

global deviceid
import lib
deviceid=123
lib.get_a()

lib.py:-

def get_a():
    global deviceid
    prnit deviceid  

calling main or trying to access deviceid from python shell is returning

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "t.py", line 4, in pp
print a
NameError: global name 'deviceid' is not defined

I tried giving global deviceid in many places inside and outside module and function.Nothing helps.

somebody please help.

Answer 1

There are no names in Python that are global to the entire program. Globals in Python are global to a particular module. To use a value in more than one module, you import its name from one module to another, making it available in two modules:

# main.py
import lib
deviceid = 123
lib.get_a()

# lib.py
import main
def get_a():
    print main.deviceid

As other commenters have pointed out, not using globals is probably a better option.

# main.py
import lib
deviceid = 123
lib.get_a(deviceid)

# lib.py
def get_a(deviceid):
    print deviceid