代码如下：

#encoding=utf-8

print '中国'

#禁止添加新的属性
def no_new_attributes(wrapped_setattr):
    def __setattr__(self, name, value):
        if hasattr(self, name):    # not a new attribute, allow setting
            wrapped_setattr(self, name, value)
        else:                      # a new attribute, forbid adding it
            raise AttributeError("can't add attribute %r to %s" % (name, self))
    return __setattr__
#核心在于设置不能添加新的属性，即修改自带的__setattr__函数
class NoNewAttrs(object):
    __setattr__ = no_new_attributes(object.__setattr__)
    class __metaclass__(type):       
        __setattr__ = no_new_attributes(type.__setattr__)
        
class Person(NoNewAttrs):
    firstname = ''
    lastname = ''
    def __init__(self, firstname, lastname):
        self.firstname = firstname
        self.lastname = lastname
    def __repr__(self):
        return 'Person(%r, %r)' % (self.firstname, self.lastname)
    
me = Person("Michere", "Simionato")
print me

me.firstname = "Michele"
print me

#Exception 不能修改属性
try: Person.address = ''
except AttributeError, err: print 'raised %r as expected' % err
try: me.address = ''
except AttributeError, err: print 'raised %r as expected' % err

中国
Person('Michere', 'Simionato')
Person('Michele', 'Simionato')
raised AttributeError("can't add attribute 'address' to <class '__main__.Person'>",) as expected
raised AttributeError("can't add attribute 'address' to Person('Michele', 'Simionato')",) as expected