gistfile1.txt

#!/usr/bin/python
# -*- encoding: utf8 -*-

class A(object):
    def __init__(self, s):
        self.s = s

    def __str__(self):
        return self.s


a = A(u'中文')
print a.__str__().encode('utf8')
print str(a).encode('utf8')

##### Here is the output #####
#
# 中文
# Traceback (most recent call last):
# File "<stdin>", line 14, in <module>
# UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)
#
# shell returned 1