How to make a python timer change a variable value

Question

I want to make a timer, so that at the end of the timer, the timer changes the value of 'timerdone'. At the end of my timer, it doesn't change the value.

Example Code:

from time import sleep

timerdone = False

def timer():
    print "3"
    sleep(1)
    print "2"
    sleep(1)
    print "1"
    sleep(1)
    timerdone = True

timer()

if timerdone == True:
    print "BOOM!"
else:
    print "Something wrong."

When I run this in terminal, it prints "Something wrong." instead of "BOOM". I know that I can just make it print "BOOM!" at the end of the timer, but this is just a simpler way of showing my problem.

Morgan Thrapp · Accepted Answer · 2015-08-21 16:28:36Z

1

You're not returning timerdone, so all you're doing is creating a new variable name timedone in the function and setting it to false. You should return it instead.

from time import sleep

def timer():
    print "3"
    sleep(1)
    print "2"
    sleep(1)
    print "1"
    sleep(1)
    return True   


if timer():
    print "BOOM!"
else:
    print "Something wrong."

answered Aug 21, 2015 at 16:28

Morgan Thrapp

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Comments

NendoTaka · Accepted Answer · 2015-08-21 16:28:08Z

1

You need to return the value. So:

from time import sleep

timerdone = False

def timer():
    print "3"
    sleep(1)
    print "2"
    sleep(1)
    print "1"
    sleep(1)
    return True

timerdone = timer()

if timerdone == True:
    print "BOOM!"
else:
    print "Something wrong."

Global variables will also work but returning a value is usually a better practice.

answered Aug 21, 2015 at 16:28

NendoTaka

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Comments

Delgan · Accepted Answer · 2015-08-21 16:26:25Z

0

You need to make your variable global.

def timer():
    global timerdone
    print "3"
    sleep(1)
    print "2"
    sleep(1)
    print "1"
    sleep(1)
    timerdone = True

If you do not use the keyword global, the variable timerdone refers to the local scope of the function timer().

Note that you can access and so read global variable without specifying the keyword, but global is needed if you want to change its value.

answered Aug 21, 2015 at 16:26

Delgan

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