Modular program construction using abstractions

Abstract

A programming methodology is presented in which modular decomposition is based on recognition of useful abstractions. Two kinds of abstractions are used, procedural abstractions and data abstractions. Decomposition is carried out during a design phase that takes place before implementation begins. The design is documented by a graph showing the relationship among abstractions and by (informal) specifications of each abstraction. The methodology is illustrated by means of a fairly large example: The design of a simplified text formatter. An implememation of the text formatter is included in the Appendix.