Tutorial 9

Introduction to Object-Oriented Design: A Minimalist Approach

Mary Beth Rosson, John M. Carroll, Virginia Polytechnic Institute & State University

Sunday, May 7

Objective

Participants will learn to (1) model a user task scenario as a set of interacting objects, using responsibility-driven design techniques to decompose a scenario's requirements, (2) build scenario scripts as a means of developing and simulating an emerging object-oriented (OO) design, (3) factor and refactor a scenario's objects into reusable abstractions, integrating across sets of related scenarios, and (4) understandthe fundamental concepts of the OO paradigm (e.g., instances and classes, encapsulation, inheritance, polymorphism, abstract classes, and frameworks).

Content

This tutorial introduces object-oriented design and is specifically tailored to the background knowledge of HCI professionals. It is organized into topics introducing elements of a scenario-based, OO design process: specifying task scenarios, identifying scenario objects, assigning object responsibilities, building scenario scripts, exploiting shared information, analyzing object roles, evolving object abstractions, supporting reuse by composition, and supporting reuse by inheritance. Each topic begins with a brief overview of a design element, followed by a demonstration of sample applications exemplifying this element. A Smalltalk-based experimental development tool, the Scenario Browser, is used in the demonstrations. A focused design exercise concludes each topic. References are provided for pursuing OO design issues in more depth.

Audience

This intermediate-level tutorial requires no background in object-oriented programming or design. Some acquaintance with the basic concerns of software develop-ment (e.g., reuse, modularity) would be useful. The tutorial assumes a general familiarity with issues in the design of interactive systems, activities associated with building a coherent task model, and using scenarios to describe user tasks.

Presentation

Lectures, demonstration, exercises

Instructors

Mary Beth Rosson and John M. Carroll have been researching issues in instruction for over fifteen years. Dr. Rosson is an associate professor and Dr. Carroll is Head of the Computer Science Department at Virginia Polytechnic Institute & State University.

Keith Instone / instone@acm.org / 95-01-05