simple persistent key-value store backed by... shelve

kv_store.py

import shelve
from contextlib import closing

class Store:
    '''Simple persistent key-value store.'''
    def __init__(self, shelf='data.shelf'):
        self.shelf = shelf
    def store(self, key, value):
        with closing(shelve.open(self.shelf)) as db:
            db[key] = value
    def get_value(self, key):
        with closing(shelve.open(self.shelf)) as db:
            return(db[key])
    def has_key(self, key):
        with closing(shelve.open(self.shelf)) as db:
            return(key in db)
    def keys(self):
        with closing(shelve.open(self.shelf)) as db:
            return(db.keys())
    def __contains__(self, key):
        return(self.has_key(key))
    def __getitem__(self, key):
        return(self.get_value(key))
    def __setitem__(self, key, value):
        self.store(key, value)
    def __delitem__(self, key):
        with closing(shelve.open(self.shelf)) as db:
            del db[key]