python 的with用途（清理资源和异常处理，同时代码精简）

参考如下博客。

https://www.cnblogs.com/DswCnblog/p/6126588.html

#!/usr/bin/env python
# with_example02.py

class Sample:
    def __enter__(self):
        print "go to enter():"
        return self

    def __exit__(self, type, value, trace):
        print "go to exit():"
        print "type:", type
        print "value:", value
        print "trace:", trace

    def do_something(self):
        print "go to do_something():"
        bar = 1/0
        return bar + 10

with Sample() as sample:
    sample.do_something()

运行结果：