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+--- Thread: Trouble with global variables (/thread-9244.html)
Trouble with global variables - maymac789 - Mar-29-2018
In the simple code below, schedule_last_update in the function check_schedule_file() is seen as a local variable and generates an error at line 15 claiming it is referenced before being assigned a value. It is assigned a value before the main() function. Why isn't that viewed as a global variable?
import os
schedule_file = "/home/pi/sprinkler/schedule.json"
schedule_last_update = os.path.getmtime(schedule_file)
schedule_current_update = schedule_last_update
def main():
print(check_schedule_file())
def check_schedule_file():
print("check_schedule_file")
try:
schedule_current_update = os.path.getmtime("/home/pi/sprinkler/schedule.json")
except:
print("check_schedule_file Error")
if schedule_current_update != schedule_last_update:
schedule_last_update = schedule_current_update
print("schedule changed")
return True
return False
if __name__=="__main__":
main()
RE: Trouble with global variables - Mekire - Mar-29-2018
You can't assign to a global name (expecting it to change globally) unless you include a
global declaration at the top of the function. The fact that you have to do this is generally indicative of a design flaw though as global variables are bad (constants fine).