Caching, overloading __getitem__ etc, memoization

gistfile1.txt

import pickle
import glob


cache = {}

def fib(x):
    if x in cache:
        return cache[x]
    if x < 2: return 1
    r = fib(x-1) + fib(x-2)
    cache[x] = r
    return r

print fib(32)


class LessMemoryDict(object):
    def __init__(self):
        pass
    def __getitem__(self, item):
        print 'getting item', item
        try:
            with open('lmd_'+item, 'r') as f:
                return pickle.load(f)
        except IOError:
            raise KeyError
    def __setitem__(self, item, value):
        print 'setting item', item, 'to', value
        with open('lmd_'+item, 'w') as f:
            pickle.dump(value, f)
    def __repr__(self):
        return repr("<LessMemoryDict object with stuff that would take too long to look up>")
    def __len__(self):
        return len(glob.glob('lmd_*'))

t = LessMemoryDict()

t['a'] = 'asdf'
print t['a']
print len(t)
print t
print t['b']


t['dog']['perro'] = .4