如何在python中制作一个可暂停的计时器？

Question

我想在 python 中创建一个具有以下功能的计时器：

timer.start() - 应该启动计时器

timer.pause() - 应该暂停计时器

timer.resume() - 应该恢复计时器

timer.get() - 应该返回当前时间

计时器应该从 0 向上运行。 它用于测量时间，而不是触发回调函数。

所以如果你启动它，它应该开始像 0 1 2 3 这样的秒数，如果你暂停它，它应该是静止的 3，但不会更进一步。 在它恢复之后，它会继续 4 5 6 等等

我怎样才能做到这一点？

---

计时器的暂停/恢复功能不是重复的，因为我不关心回调。

Answer 1

# mytimer.py
from datetime import datetime
import time

class MyTimer():
    """
    timer.start() - should start the timer
    timer.pause() - should pause the timer
    timer.resume() - should resume the timer
    timer.get() - should return the current time
    """

    def __init__(self):
        print('Initializing timer')
        self.timestarted = None
        self.timepaused = None
        self.paused = False

    def start(self):
        """ Starts an internal timer by recording the current time """
        print("Starting timer")
        self.timestarted = datetime.now()

    def pause(self):
        """ Pauses the timer """
        if self.timestarted is None:
            raise ValueError("Timer not started")
        if self.paused:
            raise ValueError("Timer is already paused")
        print('Pausing timer')
        self.timepaused = datetime.now()
        self.paused = True

    def resume(self):
        """ Resumes the timer by adding the pause time to the start time """
        if self.timestarted is None:
            raise ValueError("Timer not started")
        if not self.paused:
            raise ValueError("Timer is not paused")
        print('Resuming timer')
        pausetime = datetime.now() - self.timepaused
        self.timestarted = self.timestarted + pausetime
        self.paused = False

    def get(self):
        """ Returns a timedelta object showing the amount of time
            elapsed since the start time, less any pauses """
        print('Get timer value')
        if self.timestarted is None:
            raise ValueError("Timer not started")
        if self.paused:
            return self.timepaused - self.timestarted
        else:
            return datetime.now() - self.timestarted

if __name__ == "__main__":
    t = MyTimer()
    t.start()
    print('Waiting 2 seconds'); time.sleep(2)
    print(t.get())
    print('Waiting 1 second'); time.sleep(1)
    t.pause()
    print('Waiting 2 seconds [paused]'); time.sleep(2)
    print(t.get())
    print('Waiting 1 second [paused]'); time.sleep(1)
    print(t.get())
    print('Waiting 1 second [paused]'); time.sleep(1)
    t.resume()
    print('Waiting 1 second'); time.sleep(1)
    print(t.get())

跑

python mytimer.py

输出

Initializing timer
Starting timer
Waiting 2 seconds
Get timer value
0:00:02.001523
Waiting 1 second
Pausing timer
Waiting 2 seconds [paused]
Get timer value
0:00:03.004724
Waiting 1 second [paused]
Get timer value
0:00:03.004724
Waiting 1 second [paused]
Resuming timer
Waiting 1 second
Get timer value
0:00:04.008578