黄聪：python中defaultdict标准字典的使用

#!python
# encoding: utf-8
import collections
def default_factory():
    return 'default value'

d=collections.defaultdict(default_factory,foo='bar',ok='ok')

print 'd:',d
print 'foo=>',d['foo']
print 'ok=>',d['ok']
print 'bar=>',d['bar']