Mediators are considered basic architectural units for integration of distributed, heterogeneous information resources. In the paper we propose powerful virtual updateable views as a very high-level tool for their implementation. We assume that a view definer can explicitly determine view updates intention through procedures (being a part of a view definition) which dynamically overload generic view updating operations. We follow the Stack-Based Approach, a new theory of object-oriented query languages based on the classical concepts of programming languages, such as the environment stack and the namingscoping-binding paradigm. The proposal addresses very general object-oriented model and offers full computational power of a mediator definition language.