Question

我正在玩类，并且已经创建了一个时间部分的脚本。

import datetime


class Timer(object):

    def __init__(self, *args, **kwargs):
        self.StartTime = datetime.datetime.now()
        self.TimeElapsed = self.timedif(datetime.datetime.now(), self.StartTime)

    def hms_string(self, sec_elapsed):
        h = int(sec_elapsed / (60 * 60))
        m = int((sec_elapsed % (60 * 60)) / 60)
        s = sec_elapsed % 60
        return "{}:{:>02}:{:>05.2f}".format(h, m, s)

    def timedif(self, end_datetime, start_datetime):
        seconds_elapsed = (end_datetime - start_datetime).total_seconds()
        return self.hms_string(seconds_elapsed)

我希望它能够打印自StartTime实例化Timer.TimeElapsed以来经过的时间量。当然，它的作用是打印00:00:00。

如何修改我的课程，以便在我致电Timer.TimeElapsed时，它会使用实际当前时间与StartTime进行比较而不是调用课程的时间？

Answer 1

您可以将TimeElapsed替换为@property：

@property
def TimeElapsed(self):
    return self.timedif(datetime.datetime.now(), self.StartTime)

不要忘记从self.TimeElapsed方法中移除__init__。

另请注意，根据pep8，变量和方法名称不应位于CamelCase中。您的新媒体资源名为time_elapsed。

Answer 2

你可以改用一种方法：

import datetime
import time

class Timer(object):
    def __init__(self, *args, **kwargs):
        self.StartTime = datetime.datetime.now()
        self.TimeElapsed = self.timedif(datetime.datetime.now(), self.StartTime)

    def hms_string(self, sec_elapsed):
        h = int(sec_elapsed / (60 * 60))
        m = int((sec_elapsed % (60 * 60)) / 60)
        s = sec_elapsed % 60
        return "{}:{:>02}:{:>05.2f}".format(h, m, s)

    def timedif(self, end_datetime, start_datetime):
        seconds_elapsed = (end_datetime - start_datetime).total_seconds()
        return self.hms_string(seconds_elapsed)

    def time_elapsed(self):
        return self.timedif(datetime.datetime.now(), self.StartTime)

t = Timer()
print "time elapsed from variable: {}".format(t.TimeElapsed)
time.sleep(1)
print "time elapsed from variable: {}".format(t.TimeElapsed)

t = Timer()
print "time elapsed from method: {}".format(t.time_elapsed())
time.sleep(1)
print "time elapsed from method: {}".format(t.time_elapsed())

输出：

time elapsed from variable: 0:00:00.00
time elapsed from variable: 0:00:00.00
time elapsed from method: 0:00:00.00
time elapsed from method: 0:00:01.00

Answer 3

当您引用Timer.TimeElapsed时，您正在引用在类实例化时创建的类属性。

Python类：在调用实例时更新实例的值

3 个答案: