Load new values from another Python script

Question

I have a device which I am controlling in a for loop. I would like to check every iteration if a .txt file has changed. If it has I want to read values and send them to the device. I am checking if file was updated like this:

os.stat("myfile.txt").stat.st_mtime

This is working fine when I manually open file, write values and save file. I want to change values by another Python script which will be run by another process. In this other script I write values to the .txt file like this:

text_file = open("myfile.txt", 'w') 
text_file.write("\n0\n0\n0")
text_file.close()

When I call open(), st_mtime changes and I load nothing because text file is empty. How to deal with this? Are there other approaches besides a text file to set new values by another Python process?

Answer 1

I used 3 files. I check if 3th files st_mtime has changed. I write new values to a second file, and than open and close 3th file. St_mtime of the 3th file changes so i load values from second file safely. :)

Answer 2

You could try an alternate way to check if the contents have changed, by checking for MD5 checksum for example.

import hashlib
..
my_hex = hashlib.md5(text_file.read()).hexdigest()

You can now monitor my_hex every iteration to check if your file contents have changed.