Question

In JavaScript I am used to being able to call functions to be executed at a later time, like this

function foo() {
    alert('bar');
}

setTimeout(foo, 1000);

This does not block the execution of other code.

I do not know how to achieve something similar in Python. I can use sleep

import time
def foo():
    print('bar')

time.sleep(1)
foo()

but this will block the execution of other code. (Actually in my case blocking Python would not be a problem in itself, but I would not be able to unit test the method.)

I know threads are designed for out-of-sync execution, but I was wondering whether something easier, similar to setTimeout or setInterval exists.

Answer 1

You want a Timer object from the threading module.

from threading import Timer
from time import sleep

def foo():
    print "timer went off!"
t = Timer(4, foo)
t.start()
for i in range(11):
    print i
    sleep(.5)

If you want to repeat, here’s a simple solution: instead of using Timer, just use Thread but pass it a function that works somewhat like this:

def call_delay(delay, repetitions, func, *args, **kwargs):             
    for i in range(repetitions):    
        sleep(delay)
        func(*args, *kwargs)

This won’t do infinite loops because that could result in a thread that won’t die and other unpleasant behavior if not done right. A more sophisticated approach might use an Event-based approach, like this one.