Michael R. Levy
Abstract
The best-known solution to the sequential file update problem is the balanced-line algorithm. Here, the problem is solved using abstract data types and the resulting Cobol program illustrated. It is suggested that the program's modular decomposition aids in the development of the solution.
- 1 Dahl, O.J., Myhrhang, B., and Nygaard, K. The SIMULA 67 Common Base Language. Publication S-22, Norwegian Computing Centre, Oslo, Norway, 1970. SIMULA was one of the earliest languages to provide for the use of a capsule, or a "class" as it is here referred to. SIMULA has been a major influence in the design of several programming languages supporting abstract data types, such as Ada.Google Scholar
- 2 Dijkstra, E.W. A Discipline of Programming. Prentice-Hall, Englewood Cliffs, N.J., 1976, pp. 117-122. Dijkstra shows how his "guarded commands" approach can be used to develop the balanced-line algorithm. Google ScholarDigital Library
- 3 Dwyer, B. One more time--How to update a master file. Comm. ACM 24, 1 (Jan. 1981), pp. 3-8. Dwyer presents the balanced-line algorithm and an excellent discussion of the design principles in data processing applications. Google ScholarDigital Library
- 4 Goguen, J.A., Thatcher, J.W. and Wagner, E.G. An initial algebra approach to the specification, correctness and implementation of abstract data types. In Current Trends in Programming Methodology, Vol. IV: Data Structuring, R.T. Yeh, Ed., Prentice-Hall, Englewood Cliffs, N.J., 1978, pp. 80-149. The "ADJ" group's elegant and rigorous mathematical treatment of abstract data types. They develop a mathematical model for abstract data types, using a concept known as "Universal Algebra," and examine the problem of specifying abstract data types.Google Scholar
- 5 Guttag, J. Abstract data types and the development of data structures. Comm. ACM 20, 6 (June 1977), pp. 396-404. A very readable discussion of the use, specification, and implementation of abstract data types. It is much less mathematical than {4}, being more concerned with the use of abstract data types rather than their precise description. Google ScholarDigital Library
- 6 Liskov, B., et al. Abstraction mechanisms in CLU. Proc. ACM Conf. Language Design for Reliable Software, North Carolina, 1977 (published in SIGPLAN Notices 12, 3, pp. 166-178). CLU is an elegant programming language which supports encapsulation. Google ScholarDigital Library
- 7 Parnas, D.L. On the criteria to be used in decomposing systems into modules. Comm. ACM 15, 12 (Dec. 1972), pp. 1053-1058. Google ScholarDigital Library
- 8 The Programming Language Ada. Proposed Standard Document, United States Dept. of Defense, Washington, D.C. (published in Lecture Notes in Computer Science, No. 106, G. Goos and J. Hartmanis, Eds., Springer-Verlag, New York, 1981).Google Scholar
Index Terms
- Modularity and the sequential file update problem
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