Type Evolution Support for Complex Type Changes

Abstract

Type evolution is a serious problem for programs that use persistent data. Type changes are required during software maintenance, but can make persistent data inaccessible. Existing systems that support type evolution severely restrict the ways in which a type can be changed, thereby limiting what can be accomplished during maintenance. Tess is a system to automate type evolution for a collection of more complex type changes while providing a more natural editing environment for the programmer. Tess uses a comparative approach to identify type changes rather than a specialized editing process. Experimental results on real data indicate that Tess can accurately identify more complex type changes than those supported by existing systems relying on specialized editing. 1 Motivation Software maintenance is a serious problem for organizations developing and using software. The maintenance activity is widely recognized as extremely difficult and error-prone, with costs typically exceeding t..