- Python的with这个关键字用来对context进行管理
- 进入的时候自动持有
- 出去的时候自动释放
class MyContextManager:
def __enter__(self):
print('1. entering')
# 返回给 as 关键字
return self
def __exit__(self, exc_type, exc_val, exc_tb):
print('3. exit...')
if __name__ == "__main__":
with MyContextManager() as context:
print('2. inward')
"""
output:
1. entering
2. inward
3. exit...
"""
