最病 A On-the-fly obiect conversion a Three separate issueS: a Detection: Catch object mismatch a Notification: Make retrieving system aware of object mismatch a Correction: Bring mismatched object to a consistent state Make it a correct instance of the new class version Institute of Computer Software 2021/1/28 Nanjing UniversityOn-the-fly object conversion  Three separate issues:  Detection: ◼ Catch object mismatch  Notification: ◼ Make retrieving system aware of object mismatch  Correction: ◼ Bring mismatched object to a consistent state ◼ Make it a correct instance of the new class version 2021/1/28 Institute of Computer Software Nanjing University 49