context.py 文件源码

def __setitem__(self, key, value):
        if not hookenv.is_leader():
            raise TypeError('Not the leader. Cannot change leader settings.')
        if value is not None and not isinstance(value, six.string_types):
            # We don't do implicit casting. This would cause simple
            # types like integers to be read back as strings in subsequent
            # hooks, and mutable types would require a lot of wrapping
            # to ensure leader-set gets called when they are mutated.
            raise ValueError('Only string values allowed')
        hookenv.leader_set({key: value})