Program Slicing for Objekt-Oriented Programming Languages

Program Slicing is an analysis technique that reduces programs to those parts which are relevant for a particular computation. The programmer only has to look at the reduced program and can concentrate on the important parts. Program slicing assists the programmer in a lot of tedious and error prone tasks, such as debugging, program integration, software maintenance, testing, and software quality assurance. Two points make program slicing particularly interesting for programmers: first, export knowledge is computed automatically; second, unimportant parts are filtered away. Expert knowledge may be internal details of the program which the original author knew but never documented. With time, these details hide among the big amount of source code. Program slicing reveals many of these internal details (i.e. side-effects of functions) and shows this valuable information to the maintenance programmer. Several studies report that big organizations devote 50 % of their entire progamming effort to the maintenance of existing systems. Especially for security critical applications like aviation control systems, the development of a program instruction makes up for only one percent of the cost incurred over its entire lifetime. These numbers may appear unexpectedly high, but they illustrate how important it is to support the maintenance programmer with modern tools.