5.1 嵌套上下文管理的另类写法
============================

|image0|

当我们要写一个嵌套的上下文管理器时，可能会这样写

.. code:: python

   import contextlib

   @contextlib.contextmanager
   def test_context(name):
       print('enter, my name is {}'.format(name))

       yield

       print('exit, my name is {}'.format(name))

   with test_context('aaa'):
       with test_context('bbb'):
           print('========== in main ============')

输出结果如下

.. code:: python

   enter, my name is aaa
   enter, my name is bbb
   ========== in main ============
   exit, my name is bbb
   exit, my name is aaa

除此之外，你可知道，还有另一种嵌套写法

.. code:: python

   with test_context('aaa'), test_context('bbb'):
       print('========== in main ============')

|image1|

.. |image0| image:: http://image.iswbm.com/20200804124133.png
.. |image1| image:: http://image.iswbm.com/20200607174235.png