# A wrapper around the (optional) built-in class dbm, supporting keys

# and values of almost any type instead of just string.

# (Actually, this works only for keys and values that can be read back

# correctly after being converted to a string.)

class Dbm:

    def __init__(self, filename, mode, perm):

        import dbm

        self.db = dbm.open(filename, mode, perm)

    def __repr__(self):

        s = ''

        for key in self.keys():

            t = repr(key) + ': ' + repr(self[key])

            if s: t = ', ' + t

            s = s + t

        return '{' + s + '}'

    def __len__(self):

        return len(self.db)

    def __getitem__(self, key):

        return eval(self.db[repr(key)])

    def __setitem__(self, key, value):

        self.db[repr(key)] = repr(value)

    def __delitem__(self, key):

        del self.db[repr(key)]

    def keys(self):

        res = []

        for key in self.db.keys():

            res.append(eval(key))

        return res

    def has_key(self, key):

        return self.db.has_key(repr(key))

def test():

    d = Dbm('@dbm', 'rw', 0600)

    print d

    while 1:

        try:

            key = input('key: ')

            if d.has_key(key):

                value = d[key]

                print 'currently:', value

            value = input('value: ')

            if value is None:

                del d[key]

            else:

                d[key] = value

        except KeyboardInterrupt:

            print ''

            print d

        except EOFError:

            print '[eof]'

            break

    print d

test()