some logic help

[deanhystad]

That's odd. I ran this program:

with open("output.txt", "r") as file:
    for last_line in file:
        pass
    while True:
        for new_line in file:
            if 'Driver not connected' in new_line or 'Data stale' in new_line:
                print("Starting the driver")

Then I opened the file "output.txt", typed 'Driver not connected', and saved the file. The program promptly prints "Starting the driver" one time. I wait a while to see if this is printed again. It does not. Only once. So I append 'Driver not connected' to the output.txt and save the file. The program promptly prints "Starting the driver" one time.

I get the same behavior if I run this program.

# Get pointer to end of file
with open("output.txt", "a") as file:
    fp = file.tell()
 
while True:
    with open("output.txt", "r") as file:
        file.seek(fp)
        for line in file:
            if 'Driver not connected' in line or 'Data stale' in line:
                print("Starting the driver")
            fp += len(line)

Each program only prints the line once when I add a line to the file. What happens if you run the program on your computer? Does it behave the same?