TypeError：'NoneType'对象不可调用，但不明原因。有人能解释吗？

Question

我想写一个Python脚本，定期检查一个服务。如果这个服务没有运行，它会自动启动。下面是我的代码：

import win32serviceutil
from sched import scheduler
from time import time, sleep

s = scheduler(time, sleep)

def run_periodically(start, end, interval, func):
    event_time = start
    while event_time < end:
        s.enterabs(event_time, 0, func, ())
        event_time += interval

    s.run()



if __name__ == '__main__':    
    machine = 'George'
    service = 'Hamachi2Svc'
    action = 'start'        

    def service_info(action, machine, service):
            if win32serviceutil.QueryServiceStatus(service, machine)[1] == 4:
                print "%s is currently running" % service 
            else:
                print "%s is *not* running" % service
                print "%s is starting..." % service
                win32serviceutil.StartService(service, machine)
                print '%s started successfully' % service

    run_periodically(time()+5, time()+10, 1, service_info(action, machine, service))

这是出现的错误：

Traceback (most recent call last):
  File "C:\Python27\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 323, in RunScript
    debugger.run(codeObject, __main__.__dict__, start_stepping=0)
  File "C:\Python27\Lib\site-packages\pythonwin\pywin\debugger\__init__.py", line 60, in run
    _GetCurrentDebugger().run(cmd, globals,locals, start_stepping)
  File "C:\Python27\Lib\site-packages\pythonwin\pywin\debugger\debugger.py", line 655, in run
    exec cmd in globals, locals
  File "C:\Users\Administrator\Desktop\HamachiDestroyerV.01.py", line 1, in <module>
    import win32serviceutil
  File "C:\Users\Administrator\Desktop\HamachiDestroyerV.01.py", line 13, in run_periodically
    s.run()
  File "C:\Python27\lib\sched.py", line 117, in run
    action(*argument)
TypeError: 'NoneType' object is not callable

我在想有没有人能帮我看看我哪里做错了。我还是Python的新手，但这不是我写的第一个程序。

Answer 1

你需要注册返回值，也就是service_info()这个函数的结果；不过这个函数返回的是None，也就是没有返回任何东西。

如果你想让调度器来调用service_info()，那么你需要注册这个函数本身的引用，同时还要加上一个参数的元组：

run_periodically(time()+5, time()+10, 1, service_info, (action, machine, service))

然后你还需要调整run_periodically()这个函数，让它能够接受这些参数，并把这些参数传递给scheduler.enterabs()方法：

def run_periodically(start, end, interval, func, args=()):
    event_time = start
    while event_time < end:
        s.enterabs(event_time, 0, func, args)
        event_time += interval

    s.run()