Because of incomplete specifications or inadequate design decisions, software components developed with an object-oriented language require frequent reorganisations before they become stable, reusable classes. We propose a new incremental algorithm that analyses the redefinitions carried out on inherited properties when a class is added to a hierarchy, and restructures the hierarchy to discover missing abstractions and to enforce programming style guidelines. We illustrate our automatic restructuring approach with simple examples, describe formally the algorithm and the object model it is based on, and discuss its suitability for object-oriented software engineering.