Smalltalk

A Little Smalltalk
Timothy Budd Oregon State University

TT
Addison-Wesley Publishing Company Reading, Massachusetts • Menlo Park, California Don Mills, Ontario • Wokingham, England • Amsterdam • Sydney Singapore • Tokyo • Madrid • Bogota • Santiago • San Juan

..

We would like to thanks Tim Budd and his publisher to let us have this book available.

A Little Smalltalk has beenscanned and prepared by A. Leinhard, L. Reenggli and S. Ducasse. Note that the book does not have been OCRed because of lack of time. If you are in the mood to do it, please us. You have to pay attention about the following copyright notice. Note that it was not possible to add this notice to all the pages as footnote for obvious technical reasons.

Pearson Education, Inc. reserves the right to takeany appropriate action if you have used our intellectual property in violation of any of the requirements set forth in this permissions letter.is hereby granted permission to use the material indicated in the following acknowledgement. This acknowledgement must be carried as a footnote on every page that contains material from our book:LITTLE SMALLTALK by Timothy Budd. Reproduced by permission ofPearson Education, Inc. © 1987 Pearson Education, Inc. All rights reserved. This material may only be used in the following manner: To post the entire book to the following website http://www.iam.unibe.ch/~ducasse/webpages/freebooks.html. This permission is only given on the understanding that access to the material on your website is free to users. You agree to place a link from this book tohttp://www.aw.com/catalog/academic/discipline/1,4094,69948,00.html. Permission to post this material to your website will expire on January 1st, 2007. If you wish to continue to post the material after that date you will need to reapply for permission referencing this letter. Permission is also given for the entire book to be included on a CD-ROM. This CD-ROM permission is only given on theunderstanding that it will not be sold for profit. Any monies received from the CDROM must only be used to cover expenses in its production.This permission is non-exclusive and applies solely to publication in ONE CD-ROM EDITION and posted to the website found at http://www.iam.unibe.ch/~ducasse/webpages/freebooks.html in the following language(s) and territory:Language(s): English Territory: World NOTE:This permission does not allow the reproduction of any material copyrighted in or credited to the name of any person or entity other than the publisher named above. The publisher named above disclaims all liability in connection with your use of such material without proper consent.

"\

\

'>

\

:\

Library of Congress Cataloging-in-Publication Data Budd, Timothy. A Little SmaIItalk.Includes index. 1. Electronic digital computers-Programming. 2. Little SmaIItalk (Computer system) I. Title. QA76.6.B835 1987 005.26 86-25904 ISBN 0-201-10698-1

Reprinted with corrections April, 1987
Copyright © 1987 by Addison-Wesley Publishing Company, Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by anymeans, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission of the publisher. Printed in the United States of America. Published simultaneously in Canada. BCDEFGHIJ-DO-8987

Preface
The Little Smalltalk System: Some History
In the spring of 1984 I taught a course in programming languages at the University of Arizona. While preparing lectures for thatcourse, I became interested in the concept of object-oriented programming and, in particular, the way in which the object-oriented paradigm changed the programmers approach to problem solving. During that term and the following summer I gathered as much material as I could about objectoriented programming, especially items relating to the Smalltalk-80 programming system I developed at the Xerox...