bottle 0.5中的key-value数据库

import anydbm as dbm
import cPickle as pickle

class BottleBucket(object):
    '''Memory-caching wrapper around anydbm'''
    def __init__(self, name):
        self.__dict__['name'] = name
        self.__dict__['db'] = dbm.open('%s.db' % name, 'c')
        self.__dict__['mmap'] = {}

    def __getitem__(self, key):
        if key not in self.mmap:
            self.mmap[key] = pickle.loads(self.db[key])
        return self.mmap[key]

    def __setitem__(self, key, value):
        self.mmap[key] = value

    def __delitem__(self, key):
        if key in self.mmap:
            del self.mmap[key]
        del self.db[key]

    def __getattr__(self, key):
        try: return self[key]
        except KeyError: raise AttributeError(key)

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

    def __delattr__(self, key):
        try: del self[key]
        except KeyError: raise AttributeError(key)

    def __iter__(self):
        return iter(self.ukeys())

    def __contains__(self, key):
        return key in self.ukeys()

    def __len__(self):
        return len(self.ukeys())

    def keys(self):
        return list(self.ukeys())

    def ukeys(self):
      return set(self.db.keys()) | set(self.mmap.keys())

    def save(self):
        self.close()
        self.__init__(self.name)

    def close(self):
        for key in self.mmap.keys():
            pvalue = pickle.dumps(self.mmap[key], pickle.HIGHEST_PROTOCOL)
            if key not in self.db or pvalue != self.db[key]:
                self.db[key] = pvalue
        self.mmap.clear()
        self.db.close()

    def clear(self):
        for key in self.db.keys():
            del self.db[key]
        self.mmap.clear()

    def update(self, other):
        self.mmap.update(other)

    def get(self, key, default=None):
        try:
            return self[key]
        except KeyError:
            if default:
                return default
            raise

bb = BottleBucket("testbucket") # 打开testbucket.db，读取其中内容。若testbucket.db不存在，则会创建一个。
print bb.a      # 读取其中的内容
print bb["b"]   # 另一种读取方式
bb.c = 999      # 更新（增加）内容
bb["d"]=666     # 另一种更新方式
bb.save()       # 将数据pickle后保存到testbucket.db中，数据类型支持Python对象。