class Foo(object):
def __init__(self):
pass
def __enter__(self):
print("__enter__")
def __exit__(self, exc_type, exc_val, exc_tb):
print("__exit__")
obj = Foo()
with obj:
print("xxx")
# 结束的时候会自动触发 __exit__
# 结果
"""
__enter__
xxx
__exit__
"""
原文：https://www.cnblogs.com/ZKPython/p/11115548.html