Classes annotated with DBObject gain persistence methods.

def DBObject(table_name, versioning=VersioningTypes.NONE):
    """Classes annotated with DBObject gain persistence methods."""
    def wrapped(cls):
        field_names = set()
        all_fields = []

        for name in dir(cls):
            fld = getattr(cls, name)
            if fld and isinstance(fld, Field):
                fld.name = name
                all_fields.append(fld)
                field_names.add(name)

        def add_missing_field(name, default='', insert_pos=None):
            if name not in field_names:
                fld = Field(default=default)
                fld.name = name
                all_fields.insert(
                    len(all_fields) if insert_pos is None else insert_pos,
                    fld
                )

        add_missing_field('id', insert_pos=0)
        add_missing_field('_create_date')
        add_missing_field('_last_update')
        if versioning == VersioningTypes.DELTA_HISTORY:
            add_missing_field('_version_hist', default=list)

        # Things we count on as part of our processing
        cls.__table_name__ = table_name
        cls.__versioning__ = versioning
        cls.__fields__ = all_fields

        # Give them a ctor for free - but make sure we aren't clobbering one
        if not ctor_overridable(cls):
            raise TypeError(
                'Classes with user-supplied __init__ should not be decorated '
                'with DBObject. Use the setup method'
            )
        cls.__init__ = _auto_init

        # Duck-type the class for our data methods
        cls.get_table_name = classmethod(_get_table_name)
        cls.get_id = _get_id
        cls.set_id = _set_id
        cls.to_data = _to_data
        cls.from_data = classmethod(_from_data)
        cls.index_names = classmethod(_index_names)
        cls.indexes = _indexes
        # Bonus methods they get for using gludb.simple
        cls.get_version_hist = _get_version_hist

        # Register with our abc since we actually implement all necessary
        # functionality
        Storable.register(cls)

        # And now that we're registered, we can also get the database
        # read/write functionality for free
        cls = DatabaseEnabled(cls)

        if versioning == VersioningTypes.DELTA_HISTORY:
            cls.save = _delta_save(cls.save)

        return cls

    return wrapped