gistfile1.py

#!/usr/bin/python
import time
from collections import defaultdict


class IdleProcess(object):
    """Process data when CPU is idle
    """
    def __init__(self):
        self.poll       = []
        self.listeners  = defaultdict(list)
        

    def listen(self, event, callback):
        """Listens to an event
        """
        self.listeners[event].append(callback)


    def deafen(self, event, callback):
        """Stop listening to an event
        """
        self.listeners[event].remove(callback)


    def process(self):
        """Process the next event in the poll.
        """
        if self.poll:
            event     = self.poll.pop(0)
            callbacks = self.listeners[event['kind']]
            for callback in callbacks:
                callback(event)


    def post(self, kind, **kwargs):
        """Post a new event. When the application has some time, it'll process
        them and call the right functions that are waiting for them.
        """
        kwargs['kind'] = kind
        self.poll.append(kwargs)


# Some functions that are called when the event they're waiting for happens.
def get10(evt):
    print "10 GET!!!"


def get50(evt):
    print "50 GET!!!"


def get100(evt):
    print "100 GET!!!"


def get1000(evt):
    print "1000 GET!!!"


def any_get(evt):
    print "-- %d GET" % evt['current']


def setup(idle):
    """Mark some functions for listening to events.
    """
    idle.listen("10get",   get10)
    idle.listen("50get",   get50)
    idle.listen("100get",  get100)
    idle.listen("1000get", get1000)
    idle.listen("get",     any_get)


def main(idle):
    """Main program.
    """
    current = 1
    steps   = 5
    while True:
        steps -= 1
        if not steps:
            print "Now processing: %d" % current
            idle.post("get", current=current)
            idle.post("%dget" % current, current=current)
            current += 1
            steps    = 5

        idle.process() # let events be handled properly
        time.sleep(0.1)
        
        

if __name__ == '__main__':
    idle = IdleProcess()
    setup(idle)
    main(idle)