在python中推迟函数 [英] Postponing functions in python

问题描述

在 JavaScript 中，我习惯于能够调用稍后执行的函数，就像这样

In JavaScript I am used to being able to call functions to be executed at a later time, like this

function foo() {
    alert('bar');
}

setTimeout(foo, 1000);

这不会阻止其他代码的执行.

This does not block the execution of other code.

我不知道如何在 Python 中实现类似的功能.我可以使用睡眠

I do not know how to achieve something similar in Python. I can use sleep

import time
def foo():
    print('bar')

time.sleep(1)
foo()

但这会阻止其他代码的执行.(实际上，在我的情况下，阻塞 Python 本身并不是问题，但我无法对方法进行单元测试.)

but this will block the execution of other code. (Actually in my case blocking Python would not be a problem in itself, but I would not be able to unit test the method.)

我知道线程是为不同步执行而设计的，但我想知道是否存在类似于 setTimeout 或 setInterval 的更简单的东西.

I know threads are designed for out-of-sync execution, but I was wondering whether something easier, similar to setTimeout or setInterval exists.

推荐答案

你想要一个 Timer 对象来自 threading 模块.

You want a Timer object from the threading module.

from threading import Timer
from time import sleep

def foo():
    print "timer went off!"
t = Timer(4, foo)
t.start()
for i in range(11):
    print i
    sleep(.5)

如果你想重复，这里有一个简单的解决方案:不要使用 Timer，只需使用 Thread 而是传递一个类似这样的函数:

If you want to repeat, here's a simple solution: instead of using Timer, just use Thread but pass it a function that works somewhat like this:

def call_delay(delay, repetitions, func, *args, **kwargs):             
    for i in range(repetitions):    
        sleep(delay)
        func(*args, *kwargs)

这不会造成无限循环，因为如果做得不好，可能会导致线程不会死亡和其他令人不快的行为.更复杂的方法可能使用基于 Event 的方法，像这样.

This won't do infinite loops because that could result in a thread that won't die and other unpleasant behavior if not done right. A more sophisticated approach might use an Event-based approach, like this one.

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