python类属性在函数中更新时不更新

Question

我有一个秒表，在后台使用线程进行排序，当它更新全局变量时，它不会更改我的class属性的输出

这就是我所拥有的：

import time
from threading import Thread
s = 0
m = 0
h = 0
stopped = False

def stopwatch():
    global s
    global m
    global h
    global stopped
    while stopped == False:
        s = s + 1
        if s >= 60:
            s = 0
            m += 1
        if m >= 60:
            m = 0
            h += 1
        time.sleep(1)

class foo:
    name = 'shirb'
    time = str(h) + 'h' + str(m) + 'm' + str(s) +'s'

Thread(target = stopwatch).start()
input('press enter to stop the stopwatch')
stopped = True
print('Name: ' + foo.name + '\nTime: ' + foo.time)

假设我等了1分34秒。 输出应为：

press enter to stop the stopwatch
Name: shirb
Time: 0h1m34s

但事实上，它是这样说的：

press enter to stop the stopwatch
Name: shirb
Time: 0h0m0s

我不知道是什么原因导致它不更新。当我尝试用“print（s）”打印变量本身时，我得到了正确的秒数，因此class属性有问题，我不知道如何修复

Answer 1

您可以只使用一个类：

import time
from threading import Thread


class stopwatch:
    def __init__(self):
        self.s = 0
        self.m = 0
        self.h = 0
        self.stopped = False
        self.name = "shirb"

    def begin(self):
        while self.stopped is False:
            self.s += 1
            if self.s >= 60:
                self.s = 0
                self.m += 1
            if self.m >= 60:
                self.m = 0
                self.h += 1
            time.sleep(1)

    def get_time(self):
        return str(self.h) + "h" + str(self.m) + "m" + str(self.s) + "s"


s = stopwatch()
Thread(target=s.begin).start()
input("press enter to stop the stopwatch")
s.stopped = True
print("Name: " + s.name + "\nTime: " + s.get_time())

这就解决了问题

Answer 2

类变量在模块加载时初始化，因此foo.time在h、m和s为零时设置。但是，如果将其作为类方法，则会得到正确的结果：

class foo:
    name = 'shirb'
    
    @classmethod
    def cls_time(cls):
        return str(h) + 'h' + str(m) + 'm' + str(s) +'s'

Thread(target = stopwatch).start()
input('press enter to stop the stopwatch')
stopped = True
print('Name: ' + foo.name + '\nTime: ' + foo.cls_time())