Software Engineering Institute

Programming environments have become a focal point for much of the work directed toward improving the practice of software engineering. Such environments must provide mechanisms for recording and organizing the complex set of persistent technical and management data associated with all parts of the life cycle of large software systems. This paper focuses on one important aspect of such persistent data: how to allow evolution when the existing information must be preserved without change to maintain history. First, the role of history in programming environments is discussed. Next, the additional demands of evolution are considered and shown to lead to a set of problems. View mechanisms are suggested as a solution to the problems. A simple example involving file system directory structure is presented to illustrate these problems. A simple view mechanism, called multidirectories, is introduced and shown to solve the illustrated problems.