Python:更改线程中传递的变量并在线程外使用新值？

import threading

def change_value(event, value):
    # 模拟一些工作
    import time
    time.sleep(2)
    value.value = "new value"
    event.set()  # 设置事件，通知主线程值已更改

if __name__ == "__main__":
    value = Value('s', 'old value')  # 使用Value来共享变量
    event = threading.Event()
    t = threading.Thread(target=change_value, args=(event, value))
    t.start()

    event.wait()  # 等待事件被设置
    print("New value is:", value.value)

import threading
import queue

def change_value(q):
    # 模拟一些工作
    import time
    time.sleep(2)
    q.put("new value")

if __name__ == "__main__":
    q = queue.Queue()
    t = threading.Thread(target=change_value, args=(q,))
    t.start()

    new_value = q.get()  # 获取新值
    print("New value is:", new_value)

from concurrent.futures import ThreadPoolExecutor

def change_value():
    # 模拟一些工作
    import time
    time.sleep(2)
    return "new value"

if __name__ == "__main__":
    with ThreadPoolExecutor(max_workers=1) as executor:
        future = executor.submit(change_value)
        new_value = future.result()  # 获取新值
        print("New value is:", new_value)