在python中每N次运行一个方法

Question

我试图每 5 秒打印一个句子，我需要向它传递一个参数。

我在用threading

import threading

def printit(whatever):

  threading.Timer(5.0, printit).start()

  print(whatever)

var= "start"

printit(var)

这给了我这个错误

C:\Users\Wei Xi\Desktop>python test.py

start

Exception in thread Thread-1:

Traceback (most recent call last):

  File "C:\Users\Wei Xi\AppData\Local\Programs\Python\Python38\lib\threading.py", line 932, in _bootstrap_inner

    self.run()

  File "C:\Users\Wei Xi\AppData\Local\Programs\Python\Python38\lib\threading.py", line 1254, in run

    self.function(*self.args, **self.kwargs)

TypeError: printit() missing 1 required positional argument: 'whatever'```

Answer 1

threading.Timer构造函数接受各个目标函数 ( ) 的args关键字参数：kwargsclass threading.Timer(interval, function, args=None, kwargs=None)import threadingdef printit(whatever):  threading.Timer(5.0, printit, args=(whatever,)).start()  print(whatever)var= "start"printit(var)示例输出将是（在“无限”打印中）：startstartstartstart...

Answer 2

这是可能的解决方案之一：import threadingdef printit(whatever):     print(whatever)    threading.Timer(5.0, printit, {whatever}).start() var = "start" printit(var)您收到错误是因为您在whatever递归调用printit函数时没有传入（函数参数）。编辑：但是，此解决方案将产生无限数量的线程。如果您想将该进程作为后台任务运行，您可以这样做只使用一个线程。注意：我在这个例子中使用了 2 个参数。import timeimport threadingdef printit(whatever, whatever2, seconds=5):    while True:        print(whatever)        print(whatever2)        time.sleep(seconds)var = "start"var2 = "end"threading.Thread(target=printit, kwargs={"whatever":var, "whatever2":var2, "seconds":5}).start() print("Do something else")输出：startendDo something elsestartendstartend... (repeat start end every 5 seconds)

Answer 3

你可以使用时间：def printit(str_):   time.sleep(5)   print(str_)var = "start"while True:     printit(var)

Answer 4

您可以time.sleep()在 while 循环中使用该函数：import timedef printit(whatever, seconds=5):    while True:        print(whatever)        time.sleep(seconds)var= "start"printit(var) # prints "start" every 5 seconds#start#start#start