Thanks for answer Eugene. Zexplore doesn't seem to help me, however.
I wish to avoid spending several lines by building a hierarchy of NaElement objects to get a simple "state = restricted" filtering query, which is what Zexplore does. Instead, I look for an elegant way to directly pass query or desired-attributes arguments to invoke method, not to invoke_elem one. Something in the way of the example I've provided in original post.