python - 在python中每X秒执行一个函数(带参数)

Question

我想运行一个代码，每 5 秒运行一个带有参数的函数(例如 greet(h))。我尝试使用threading 但它不起作用。它只执行一次。请参阅下面的代码和错误:

import threading

oh_hi = "Hi guys"

def greeting(hello):
    print "%s" % hello



threading.Timer(1, greeting(oh_hi)).start()

错误如下所示:

> >>> ================================ RESTART
> ================================
> >>>  Hi guys
> >>> Exception in thread Thread-1: Traceback (most recent call last):  
> File "C:\Python27\lib\threading.py",
> line 530, in __bootstrap_inner
>     self.run()   File "C:\Python27\lib\threading.py", line
> 734, in run
>     self.function(*self.args, **self.kwargs) TypeError: 'NoneType' object is not callable

请提供帮助。

谢谢

Answer 1

正如其他人指出的那样，错误是因为您没有将正确的参数传递给 threading.Timer()方法。更正将在 5 秒后运行您的函数一次。有很多方法可以让它重复。

安object-oriented方法是派生一个新的 threading.Thread子类。虽然可以创建一个专门做你想做的事情——即 print "%s" % hello -- 制作一个更通用的、参数化的、将调用在其实例化期间传递给它的函数的子类(就像 threading.Timer() )稍微困难一点。如下图所示:

import threading
import time

class RepeatEvery(threading.Thread):
    def __init__(self, interval, func, *args, **kwargs):
        threading.Thread.__init__(self)
        self.interval = interval  # seconds between calls
        self.func = func          # function to call
        self.args = args          # optional positional argument(s) for call
        self.kwargs = kwargs      # optional keyword argument(s) for call
        self.runable = True
    def run(self):
        while self.runable:
            self.func(*self.args, **self.kwargs)
            time.sleep(self.interval)
    def stop(self):
        self.runable = False

def greeting(hello):
    print hello

thread = RepeatEvery(3, greeting, "Hi guys")
print "starting"
thread.start()
thread.join(21)  # allow thread to execute a while...
thread.stop()
print 'stopped'

输出:

# starting
# Hi guys
# Hi guys
# Hi guys
# Hi guys
# Hi guys
# Hi guys
# Hi guys
# stopped

除了重写基础 threading.Thread类(class)的__init__()和 run()方法，一个stop()添加了方法以允许在需要时终止线程。我还简化了 print "%s" % hello在你的greeting()功能只是print hello .