python 中__getattr__ 以及 __setattr__

#!/usr/bin/env python

class Dict(dict):

def __init__(self, **kw):
super(Dict, self).__init__(**kw)

def __getattr__(self, key):
try:
return self[key]
except KeyError:
raise AttributeError(r"'Dict' object has no attribute '%s'" % key)

def __setattr__(self, key, value):
self[key] = value

d = Dict(a=1, b=2)
print d['a']
# use __getattr__ function
print d.a
print d.b
# use __setattr__ function
d.b = 3
print d.b
#print d.c

class Test():
def __getattr__(self, a):
return a

t = Test()
print t.ni

1
1
2
3
ni

import unittest

from mydict import Dict

class TestDict(unittest.TestCase):

def setUp(self):
print('setUp...')

def tearDown(self):
print('tearDown...')

def test_init(self):
d = Dict(a=1, b='test')
self.assertEqual(d.a, 1)
self.assertEqual(d.b, 'test')
self.assertTrue(isinstance(d, dict))

def test_key(self):
d = Dict()
d['key'] = 'value'
self.assertEqual(d.key, 'value')

def test_attr(self):
d = Dict()
d.key = 'value'
self.assertTrue('key' in d)
self.assertEqual(d['key'], 'value')

def test_keyerror(self):
d = Dict()
with self.assertRaises(KeyError):
value = d['empty']

def test_attrerror(self):
d = Dict()
with self.assertRaises(AttributeError):
value = d.empty

if __name__ == '__main__':
unittest.main()