永続辞書を実現するshelveモジュールに圧縮機能を付けたgzshelveというのを作った． 以下にソースコードを示す．shelve.open() の代わりにgzsheleve.open() を使えば圧縮機能付き永続辞書になる．ただし，速度は期待しないでください…．

# -*- coding: utf-8 -*-

import shelve, anydbm
from zlib import compress, decompress

try:
    from cPickle import Pickler, Unpickler
except ImportError:
    from pickle import Pickler, Unpickler

try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO

class gzShelf(shelve.Shelf) :
    def __init__(self, dict, protocol=None, writeback=False, binary=None) :
        shelve.Shelf.__init__(self, dict, protocol, writeback, binary)

    def __getitem__(self, key) :
        try:
            value = self.cache[key]
        except KeyError:
            f = StringIO(decompress(self.dict[key]))
            value = Unpickler(f).load()
            if self.writeback:
                self.cache[key] = value
        return value

    def __setitem__(self, key, value):
        if self.writeback:
            self.cache[key] = value
        f = StringIO()
        p = Pickler(f, self._protocol)
        p.dump(value)
        self.dict[key] = compress(f.getvalue())

def open(filename, flag='c', protocol=None, writeback=False, binary=None) :
    db = anydbm.open(filename, flag)
    return gzShelf(db, protocol, writeback, binary)