test1.py

#!/usr/bin/env python2
# -*- coding: utf-8 -*-
# Pw @ 2013-06-22 19:56:30


class Test:

    def count(self,n):
       while n > 0:
           yield n
           n -= 1

    def __enter__(self):
        return self.count(9)

    def __exit__(self, exception_type, exception_val, trace):
        try:
            self.obj.close()
        except AttributeError:
            print 'Not closable.'
        return True

with Test() as t:
    while True:
        print t.next()