python hidden features

from http://stackoverflow.com/questions/101268/hidden-features-of-python
http://www.okpython.com/bbs/thread-3434-1-1.html
http://www.okpython.com/bbs/thread-3436-1-2.html
http://www.okpython.com/bbs/thread-3437-1-2.html
http://www.okpython.com/bbs/thread-3438-1-1.html
http://www.okpython.com/bbs/thread-3439-1-1.html
http://www.okpython.com/bbs/thread-3440-1-1.html
http://www.okpython.com/bbs/thread-3441-1-1.html
#74 Ì«ÀÁ¶ø²»Ô¸¶Ô×Öµä½øÐгõʼ»¯£¿Ã»ÎÊÌ⣡
# n Python > 2.3:

from collections import defaultdict
In Python <= 2.3:

def defaultdict(type_):
class Dict(dict):
def __getitem__(self, key):
return self.setdefault(key, type_())
return Dict()
In any version:

d = defaultdict(list)
for stuff in lots_of_stuff:
d[stuff.name].append(stuff)