python：waitfor轮询

def waitfor(getter, timeout=3, interval=0.5, *args):
	starttime = datetime.datetime.now()
	while True:
		if getter(args):
			return
		else:
			runtime = datetime.datetime.now() - starttime
			print runtime
			if runtime.seconds >= timeout:
				raise Exception
			time.sleep(interval)
	
current_value = 1	
def testgetval(args):
	wanted_value = args[0]
	global current_value
	current_value += 1
	print '%d, %d' % (wanted_value, current_value)
	return current_value > wanted_value	
		
if __name__ == '__main__':
	waitfor(testgetval, 1, 0.3, 2)
	print '======================='
	waitfor(testgetval, 1, 0.3, 8)