Generic function, fetching attribute order for relational objects.
attrs_order(x, ...)attrs_order(x, ...) <- value
A character vector, giving attributes in the order in which they're
prioritised for sorting within x.
an R object, such as a functional_dependency,
relation_schema, relation,
database_schema, or database object.
further arguments passed on to methods.
A character vector of the same length as attrs_order(x, ...).
All classes in autodb contain an attrs_order attribute. It
gives an easy way to find a list of all attributes/variables involved in an
object, but its main purpose is to also assign those attributes a consistent
order when printing or plotting the object.