Python上下文管理

import queue
import contextlib
import time
@contextlib.contextmanager
def worker_state(xxx,val):
    xxx.append(val)
    print("before",xxx)
    try:
        time.sleep(1)
        yield
    finally:
        xxx.remove(val)
        print("after",xxx)

if __name__ == '__main__':
    q = queue.Queue()
    q.put("123")
    li = []
    with worker_state(li,1):
        q.get()

C:\Python35\python3.exe F:/Python/taochen/day22/a15.py
before [1]
after []

Process finished with exit code 0