The need for flexible object invariants
Alexander J. Summers, Sophia Drossopoulou, Péter Müller · 2009
Specification and verification of object oriented programs usually features in some capacity the concept of an object invariant, used to describe the consistent states of an object. Unavoidably, an object's invariant will be broken at some points in its lifetime, and as a result, invariant protocols have been suggested, which prescribe the times at which object invariants may be broken, and the points at which they have to be re-established.