The First Experience of Class Evolution Support in PJama

The design and implementation of the initial release of class evolution technology for PJama persistent language is described. This technology supports modi cations to individual classes, class hierarchy, and user-de ned conversion of data contained in class instances when a modi cation to this class leads to the change of instance format. PJama evolution technology was evaluated on an application of considerable size and proved to be very helpful for a PJama programmer.