Variables being overridden to initial values.

[p2bc]

Hello first post... as a Python user.

A long time PHP coder, trying to make the move over to Django, so I figured I would try my hand at a backup script to get my feet wet with Python. I have played with Python here and there, but this is my first serious attempt at an actual script that I plan to use on a daily bases.

Here my script:

#!/usr/bin/python3*

'''
	Module name:
	Author: 
	Contact: 
	Desc: 
'''
__version__ = '0.0.1'

import shutil
import os, os.path
import datetime



TODAYS_DATE = str(datetime.date.today())

NUMBER_OF_BACKUP = 3

BACKUP_LOCATION = '/home/Superusr/Backup_Scripts/Test_01/Save_Location/'
FOLDER2BACKUP = '/home/Superusr/Backup_Scripts/Test_01/Sample_Folder'

CURRENT_BACKUP_NAME = FOLDER2BACKUP + "_" + TODAYS_DATE

CURRENT_LIST_OF_BACKUPS = []
MOST_RECENT_BACKUP = "Newest"
OLDEST_BACKUP = "Oldest"


def GET_MOST_RECENT_BACKUP_NAME():
	print("Step 2...")
	for names in os.listdir(BACKUP_LOCATION):
		CURRENT_LIST_OF_BACKUPS.append(names)
	
	CURRENT_LIST_OF_BACKUPS.sort()	
	
def SET_MOST_RECENT_BACKUP():
	print("Step 3...")
	MOST_RECENT_BACKUP = CURRENT_LIST_OF_BACKUPS[-1]
	print(MOST_RECENT_BACKUP)
	
def SET_OLDEST_BACKUP():
	print("Step 4...")
	OLDEST_BACKUP = CURRENT_LIST_OF_BACKUPS[0]
	print(OLDEST_BACKUP)



def INITIAL_SETUP():
	print("Step 1...")
	GET_MOST_RECENT_BACKUP_NAME()
	SET_MOST_RECENT_BACKUP()
	SET_OLDEST_BACKUP()

def main():
	INITIAL_SETUP()
	print("Most recent backup is: {}".format(MOST_RECENT_BACKUP))

if __name__ == "__main__": main()

With a result of:

Output:
Step 1...
Step 2...
Step 3...
Sample_Folder_2020-09-15
Step 4...
Sample_Folder_2020-09-01
Most recent backup is: Newest


------------------
(program exited with code: 0)
Press return to continue

So yes, this is a basic script, I am building it up, but that is the puzzling part. I put the print statements ("print('Step 1...')" in to make sure each function was being called to troubleshoot.
Originally, without the print statements, and the initial variables set to blank ("MOST_RECENT_BACKUP = ''") it was coming back blank with no errors. So after setting an initial value to the variables, and comparing that to the results after each step I realised my variables were being reset to initial setting even though they were defined out of scope. I was thinking it possibly could be because a "global variables" problem vs. a local variable, but the "CURRENT_LIST_OF_BACKUPS" variable is outside, and is initialised and is maintained through the parsing of the script, so I don't know why "MOST_RECENT_BACKUP" and "OLDEST_BACKUP" are not maintaining their new values and are returning to their initial value instead.

I am sure it is a simple oversight on my part, but I honestly don't see it.

Any help would be appreciated, thanks in advance.


OS: Ubuntu 20.04
Python Version: Python 3.8.2