In this talk, I present a new model of class-based Algol-like programming
languages inspired by automata-theoretic concepts. The model may be seen as
a variant of the "object-based" model previously developed in 1993, where
objects are described by their observable behaviour in terms of events, and
"state-based" models studied by Reynolds, Oles, Tennent and O'Hearn where
objects are not explicitly represented. The idea is to view objects as
automata which are described from the outside through their observable
behaviour while, internally, their operations are represented as state
transformations. This allows us to to combine both the state-based and
event-based views of objects. I illustrate the efficacy of the model by
proving several test equivalences and discuss its connections to the
previous models.