'Add a set of objects to this object store.
:param objects: Iterable over (object, path) tuples, should support
__len__.
:return: Pack object of the objects written.'

def add_objects(self, objects):

    if (len(objects) == 0):
        return
    (f, commit, abort) = self.add_pack()
    try:
        write_pack_objects(f, objects)
    except:
        abort()
        raise
    else:
        return commit()
