Crindy was born out of my frustration with trying to write applications in Python that have several timer-based loops running at different frequencies. My initial approach used Python threads, but that approach is nasty for a number of reasons, the most pertinent being that these eventloops aren't really doing any concurrent processing other that sleeping and that there is no mechanism for killing threads. Even if there were, there isn't a good, Pythonic equivalent of destructors, so I was left propagating kill flags to all of the encapsulated threads. Blech.

Enter crindy. Crindy exposes a simple interface similar to Javascript's setTimeout call and has a built-in message pump. As a result, creating applications with crindy is similar to creation applications in node.js: when modules are created, they register their first timeout and callback, which then registers other callbacks as appropriate. When the message pump runs dry, the application is over.

import crindy
import time

def c0():
    print "c0 called at time %s" % (time.time(),)

def c1(a, b, c):
    print "c2 called at time %s with values %s %s %s" % (time.time(), a, b, c)
    crindy.add_event(1, c2, [666])

def c2(a):
    print "c2 called at time %s with value %s" % (time.time(), a)

if __name__ == "__main__":
    crindy.add_event(0, c0)
    crindy.add_event(2, c0)
    crindy.add_event(4, c0)
    crindy.add_event(1, c1, ["yes", "no", "maybe"])
    crindy.run()

This will output the following:

c0 called at time 1323020603.55
c2 called at time 1323020604.55 with values yes no maybe
c0 called at time 1323020605.55
c2 called at time 1323020605.55 with value 666
c0 called at time 1323020607.56