Global Variable in Python cross module

Question

I have two Python modules:

one.py; and
two.py

I want to change X global variable in two.py.Script two.py running. After I run one.py

one.py

#!/usr/bin/env python

import two

def main():
 two.function("20")

if __name__=="__main__":
    main()

two.py

#!/usr/bin/env python

X="10"
def main():
 while True:
  function()
 time.sleep(0.25)

def function(input="00"):
 if(input!="00"):
      global X
      X=input
      print "change"

 print X
if __name__=="__main__":
  main()

console:

sudo python two.py

10
10
10
10

after I run one.py  but no change in two.py

Well you'll be running two.py as a separate Python process than one.py so you can't really change global variables like that. You'll need some kind of inter-process communication. — Tagc
– Tagc, Commented Jan 17, 2017 at 21:41

Mathieu Paturel · Accepted Answer · 2017-01-18 00:31:09Z

1

after I run one.py but no change in two.py

What you're doing dynamically changes the variables. It doesn't re-write the files.

Which is in fact, what you might want to do.

myfile.txt

reader.py

with open('myfile.txt', 'r') as fp:
    nb = int(fp.read())
    print(nb)

writer.py

with open('myfile.txt', 'w') as fp:
    fp.write('6')

Now, if you run reader.py, it'll output 5. Then if you run writer.py, it'll output nothing, just replace the entire content of myfile.txt with 6. And then, rerun reader.py, it'll output 6, because the content of the file as changed. It works because, unlike your program that you run, the files' content doesn't depend of a process, it's "static".

answered Jan 18, 2017 at 0:31

Mathieu Paturel

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1 Comment

user7432329 Over a year ago

It is Solutions Thank you

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