Python上下文管理使用

 import contextlib
 from queue import Queue

 @contextlib.contextmanager
 def myOpen(file):
     f = open(file)
     try:
         yield f #返回f到with...as..语句中的f
     finally:
         f.close()
 file = r"D:\text.txt"
 with myOpen(file) as f:
     #在执行这块代码时，会先执行worker_state中yield前面的代码
     #执行完这块代码后，会执行worker_state中finally的代码
     for line in f:
         print(line)