  We compare two different notions of generic expansions of countable saturated
structures. One kind of genericity is related to model-companions and to
amalgamation constructions \'a la Hrushovski-Fra\"iss\'e. Another notion of
generic expansion is defined via topological properties and Baire category
theory. The second type of genericity was first formulated by Truss for
automorphisms. We work with a later generalization, due to Ivanov, to finite
tuples of predicates and functions.
