the-pragmatic-programmer.pdf

Prepared exclusively for Zach What others in the trenches say about The Pragmatic Programmer... “The cool thing about this book is that it’s great for keeping the programming process fresh. [The book] helps you to continue to grow and clearly comes from people who have been there.” Kent Beck, author of Extreme Programming Explained: Embrace Change “I found this book to be a great mix of solid advice and wonderful analogies!” Martin Fowler, author of Refactoring and UML Distilled “I would buy a copy, read it twice, then tell all my colleagues to run out and grab a copy. This is a book I would never loan because I would worry about it being lost.” Kevin Ruland, Management Science, MSG-Logistics “The wisdom and practical experience of the authors is obvious. The topics presented are relevant and useful.... By far its greatest strength for me has been the outstanding analogies—tracer bullets, broken windows, and the fabulous helicopter-based explanation of the need for orthogonality, especially in a crisis situation. I have little doubt that this book will eventually become an excellent source of useful information for journeymen programmers and expert mentors alike.” John Lakos, author of Large-Scale C++ Software Design Prepared exclusively for Zach “This is the sort of book I will buy a dozen copies of when it comes out so I can give it to my clients.” Eric Vought, Software Engineer “Most modern books on software development fail to cover the basics of what makes a great software developer, instead spending their time on syntax or technology where in reality the greatest leverage possible for any software team is in having talented developers who really know their craft well. An excellent book.” Pete McBreen, Independent Consultant “Since reading this book, I have implemented many of the practical suggestions and tips it contains. Across the board, they have saved my company time and money while helping me get my job done quicker! This should be a desktop reference for everyone who works with code for a living.” Jared Richardson, Senior Software Developer, iRenaissance, Inc. “I would like to see this issued to every new employee at my company....” Chris Cleeland, Senior Software Engineer, Object Computing, Inc. Prepared exclusively for Zach The Pragmatic Programmer Prepared exclusively for Zach This page intentionally left blank Prepared exclusively for Zach The Pragmatic Programmer From Journeyman to Master Andrew Hunt David Thomas ADDISON–WESLEY An imprint of Addison Wesley Longman, Inc. Reading, Massachusetts Harlow, England Menlo Park, California Berkeley, California Don Mills, Ontario Sydney Bonn Amsterdam Tokyo Mexico City Prepared exclusively for Zach Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and Addison– Wesley was aware of a trademark claim, the designations have been printed in initial capital letters or in all capitals. Lyrics from the song “The Boxer” on page 157 are Copyright c 1968 Paul Simon. Used by permission of the Publisher: Paul Simon Music. Lyrics from the song “Alice’s Restaurant” on page 220 are by Arlo Guthrie, c 1966, 1967 (renewed) by A PPLESEED M USIC I NC. All Rights Reserved. Used by Permission. The authors and publisher have taken care in the preparation of this book, but make no express or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of the use of the information or programs contained herein. The publisher offers discounts on this book when ordered in quantity for special sales. For more information, please contact: AWL Direct Sales Addison Wesley Longman, Inc. One Jacob Way Reading, Massachusetts 01867 (781) 944-3700 Visit AWL on the Web: www.awl.com/cseng Library of Congress Cataloging-in-Publication Data Hunt, Andrew, 1964 – The Pragmatic Programmer / Andrew Hunt, David Thomas. p. cm. Includes bibliographical references. ISBN 0-201-61622-X 1. Computer programming. I. Thomas, David, 1956–. II. Title. QA76.6.H857 1999 005.1--dc21 99–43581 CIP Copyright c 2000 by Addison Wesley Longman, Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photo- copying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America. Published simultaneously in Canada. ISBN 0-201-61622-X Text printed in the United States on recycled paper at Courier Stoughton in Stoughton, Massachusetts. 25th Printing February 2010 Prepared exclusively for Zach For Ellie and Juliet, Elizabeth and Zachary, Stuart and Henry Prepared exclusively for Zach This page intentionally left blank Prepared exclusively for Zach Contents F OREWORD xiii P REFACE xvii 1 A P RAGMATIC P HILOSOPHY 1 1. The Cat Ate My Source Code................. 2 2. Software Entropy........................ 4 3. Stone Soup and Boiled Frogs................. 7 4. Good-Enough Software.................... 9 5. Your Knowledge Portfolio................... 12 6. Communicate!......................... 18 2 A P RAGMATIC A PPROACH 25 7. The Evils of Duplication.................... 26 8. Orthogonality.......................... 34 9. Reversibility........................... 44 10. Tracer Bullets......................... 48 11. Prototypes and Post-it Notes................. 53 12. Domain Languages...................... 57 13. Estimating........................... 64 3 T HE B ASIC T OOLS 71 14. The Power of Plain Text.................... 73 15. Shell Games.......................... 77 16. Power Editing.......................... 82 17. Source Code Control...................... 86 18. Debugging............................ 90 19. Text Manipulation....................... 99 20. Code Generators........................ 102 ix Prepared exclusively for Zach x C ONTENTS 4 P RAGMATIC PARANOIA 107 21. Design by Contract...................... 109 22. Dead Programs Tell No Lies................. 120 23. Assertive Programming.................... 122 24. When to Use Exceptions................... 125 25. How to Balance Resources.................. 129 5 B END , OR B REAK 137 26. Decoupling and the Law of Demeter............. 138 27. Metaprogramming....................... 144 28. Temporal Coupling....................... 150 29. It’s Just a View......................... 157 30. Blackboards.......................... 165 6 W HILE Y OU A RE C ODING 171 31. Programming by Coincidence................ 172 32. Algorithm Speed........................ 177 33. Refactoring........................... 184 34. Code That’s Easy to Test................... 189 35. Evil Wizards.......................... 198 7 B EFORE THE P ROJECT 201 36. The Requirements Pit..................... 202 37. Solving Impossible Puzzles.................. 212 38. Not Until You’re Ready.................... 215 39. The Speciﬁcation Trap.................... 217 40. Circles and Arrows....................... 220 8 P RAGMATIC P ROJECTS 223 41. Pragmatic Teams........................ 224 42. Ubiquitous Automation.................... 230 43. Ruthless Testing........................ 237 44. It’s All Writing......................... 248 45. Great Expectations...................... 255 46. Pride and Prejudice...................... 258 Prepared exclusively for Zach C ONTENTS xi Appendices A R ESOURCES 261 Professional Societies........................ 262 Building a Library.......................... 262 Internet Resources......................... 266 Bibliography............................. 275 B A NSWERS TO E XERCISES 279 I NDEX 309 Prepared exclusively for Zach This page intentionally left blank Prepared exclusively for Zach Foreword As a reviewer I got an early opportunity to read the book you are hold- ing. It was great, even in draft form. Dave Thomas and Andy Hunt have something to say, and they know how to say it. I saw what they were doing and I knew it would work. I asked to write this foreword so that I could explain why. Simply put, this book tells you how to program in a way that you can follow. You wouldn’t think that that would be a hard thing to do, but it is. Why? For one thing, not all programming books are written by pro- grammers. Many are compiled by language designers, or the journalists who work with them to promote their creations. Those books tell you how to talk in a programming language—which is certainly important, but that is only a small part of what a programmer does. What does a programmer do besides talk in programming language? Well, that is a deeper issue. Most programmers would have trouble explaining what they do. Programming is a job ﬁlled with details, and keeping track of those details requires focus. Hours drift by and the code appears. You look up and there are all of those statements. If you don’t think carefully, you might think that programming is just typing statements in a programming language. You would be wrong, of course, but you wouldn’t be able to tell by looking around the programming section of the bookstore. In The Pragmatic Programmer Dave and Andy tell us how to program in a way that we can follow. How did they get so smart? Aren’t they just as focused on details as other programmers? The answer is that they paid attention to what they were doing while they were doing it—and then they tried to do it better. Imagine that you are sitting in a meeting. Maybe you are thinking that the meeting could go on forever and that you would rather be programming. Dave and Andy would be thinking about why they were xiii Prepared exclusively for Zach xiv F OREWORD having the meeting, and wondering if there is something else they could do that would take the place of the meeting, and deciding if that some- thing could be automated so that the work of the meeting just happens in the future. Then they would do it. That is just the way Dave and Andy think. That meeting wasn’t some- thing keeping them from programming. It was programming. And it was programming that could be improved. I know they think this way because it is tip number two: Think About Your Work. So imagine that these guys are thinking this way for a few years. Pretty soon they would have a collection of solutions. Now imagine them using their solutions in their work for a few more years, and discarding the ones that are too hard or don’t always produce results. Well, that approach just about deﬁnes pragmatic. Now imagine them taking a year or two more to write their solutions down. You might think, That information would be a gold mine. And you would be right. The authors tell us how they program. And they tell us in a way that we can follow. But there is more to this second statement than you might think. Let me explain. The authors have been careful to avoid proposing a theory of software development. This is fortunate, because if they had they would be obliged to warp each chapter to defend their theory. Such warping is the tradition in, say, the physical sciences, where theories eventually become laws or are quietly discarded. Programming on the other hand has few (if any) laws. So programming advice shaped around wanna-be laws may sound good in writing, but it fails to satisfy in practice. This is what goes wrong with so many methodology books. I’ve studied this problem for a dozen years and found the most promise in a device called a pattern language. In short, a pattern is a solution, and a pattern language is a system of solutions that reinforce each other. A whole community has formed around the search for these systems. This book is more than a collection of tips. It is a pattern language in sheep’s clothing. I say that because each tip is drawn from experi- ence, told as concrete advice, and related to others to form a system. These are the characteristics that allow us to learn and follow a pattern language. They work the same way here. Prepared exclusively for Zach F OREWORD xv You can follow the advice in this book because it is concrete. You won’t ﬁnd vague abstractions. Dave and Andy write directly for you, as if each tip was a vital strategy for energizing your programming career. They make it simple, they tell a story, they use a light touch, and then they follow that up with answers to questions that will come up when you try. And there is more. After you read ten or ﬁfteen tips you will begin to see an extra dimension to the work. We sometimes call it QWAN, short for the quality without a name. The book has a philosophy that will ooze into your consciousness and mix with your own. It doesn’t preach. It just tells what works. But in the telling more comes through. That’s the beauty of the book: It embodies its philosophy, and it does so unpre- tentiously. So here it is: an easy to read—and use—book about the whole practice of programming. I’ve gone on and on about why it works. You probably only care that it does work. It does. You will see. —Ward Cunningham Prepared exclusively for Zach This page intentionally left blank Prepared exclusively for Zach Preface This book will help you become a better programmer. It doesn’t matter whether you are a lone developer, a member of a large project team, or a consultant working with many clients at once. This book will help you, as an individual, to do better work. This book isn’t theoretical—we concentrate on practical topics, on using your experi- ence to make more informed decisions. The word pragmatic comes from the Latin pragmaticus—“skilled in business”—which itself is derived from the Greek , meaning “to do.” This is a book about doing. Programming is a craft. At its simplest, it comes down to getting a computer to do what you want it to do (or what your user wants it to do). As a programmer, you are part listener, part advisor, part interpreter, and part dictator. You try to capture elusive requirements and ﬁnd a way of expressing them so that a mere machine can do them justice. You try to document your work so that others can understand it, and you try to engineer your work so that others can build on it. What’s more, you try to do all this against the relentless ticking of the project clock. You work small miracles every day. It’s a difﬁcult job. There are many people offering you help. Tool vendors tout the mir- acles their products perform. Methodology gurus promise that their techniques guarantee results. Everyone claims that their programming language is the best, and every operating system is the answer to all conceivable ills. Of course, none of this is true. There are no easy answers. There is no such thing as a best solution, be it a tool, a language, or an operat- ing system. There can only be systems that are more appropriate in a particular set of circumstances. xvii Prepared exclusively for Zach xviii P REFACE This is where pragmatism comes in. You shouldn’t be wedded to any particular technology, but have a broad enough background and expe- rience base to allow you to choose good solutions in particular situ- ations. Your background stems from an understanding of the basic principles of computer science, and your experience comes from a wide range of practical projects. Theory and practice combine to make you strong. You adjust your approach to suit the current circumstances and envi- ronment. You judge the relative importance of all the factors affecting a project and use your experience to produce appropriate solutions. And you do this continuously as the work progresses. Pragmatic Program- mers get the job done, and do it well. Who Should Read This Book? This book is aimed at people who want to become more effective and more productive programmers. Perhaps you feel frustrated that you don’t seem to be achieving your potential. Perhaps you look at col- leagues who seem to be using tools to make themselves more produc- tive than you. Maybe your current job uses older technologies, and you want to know how newer ideas can be applied to what you do. We don’t pretend to have all (or even most) of the answers, nor are all of our ideas applicable in all situations. All we can say is that if you follow our approach, you’ll gain experience rapidly, your produc- tivity will increase, and you’ll have a better understanding of the entire development process. And you’ll write better software. What Makes a Pragmatic Programmer? Each developer is unique, with individual strengths and weaknesses, preferences and dislikes. Over time, each will craft his or her own personal environment. That environment will reﬂect the programmer’s individuality just as forcefully as his or her hobbies, clothing, or hair- cut. However, if you’re a Pragmatic Programmer, you’ll share many of the following characteristics: Early adopter/fast adapter. You have an instinct for technologies and techniques, and you love trying things out. When given some- Prepared exclusively for Zach P REFACE xix thing new, you can grasp it quickly and integrate it with the rest of your knowledge. Your conﬁdence is born of experience. Inquisitive. You tend to ask questions. That’s neat—how did you do that? Did you have problems with that library? What’s this BeOS I’ve heard about? How are symbolic links implemented? You are a pack rat for little facts, each of which may affect some decision years from now. Critical thinker. You rarely take things as given without ﬁrst get- ting the facts. When colleagues say “because that’s the way it’s done,” or a vendor promises the solution to all your problems, you smell a challenge. Realistic. You try to understand the underlying nature of each problem you face. This realism gives you a good feel for how difﬁ- cult things are, and how long things will take. Understanding for yourself that a process should be difﬁcult or will take a while to complete gives you the stamina to keep at it. Jack of all trades. You try hard to be familiar with a broad range of technologies and environments, and you work to keep abreast of new developments. Although your current job may require you to be a specialist, you will always be able to move on to new areas and new challenges. We’ve left the most basic characteristics until last. All Pragmatic Pro- grammers share them. They’re basic enough to state as tips: TIP 1 Care About Your Craft We feel that there is no point in developing software unless you care about doing it well. TIP 2 Think! About Your Work In order to be a Pragmatic Programmer, we’re challenging you to think about what you’re doing while you’re doing it. This isn’t a one-time audit of current practices—it’s an ongoing critical appraisal of every Prepared exclusively for Zach xx P REFACE decision you make, every day, and on every development. Never run on auto-pilot. Constantly be thinking, critiquing your work in real time. The old IBM corporate motto, THINK!, is the Pragmatic Programmer’s mantra. If this sounds like hard work to you, then you’re exhibiting the realistic characteristic. This is going to take up some of your valuable time—time that is probably already under tremendous pressure. The reward is a more active involvement with a job you love, a feeling of mastery over an increasing range of subjects, and pleasure in a feeling of continuous improvement. Over the long term, your time investment will be repaid as you and your team become more efﬁcient, write code that’s easier to maintain, and spend less time in meetings. Individual Pragmatists, Large Teams Some people feel that there is no room for individuality on large teams or complex projects. “Software construction is an engineering disci- pline,” they say, “that breaks down if individual team members make decisions for themselves.” We disagree. The construction of software should be an engineering discipline. How- ever, this doesn’t preclude individual craftsmanship. Think about the large cathedrals built in Europe during the Middle Ages. Each took thousands of person-years of effort, spread over many decades. Lessons learned were passed down to the next set of builders, who advanced the state of structural engineering with their accomplishments. But the carpenters, stonecutters, carvers, and glass workers were all craftspeo- ple, interpreting the engineering requirements to produce a whole that transcended the purely mechanical side of the construction. It was their belief in their individual contributions that sustained the projects: We who cut mere stones must always be envisioning cathedrals. — Quarry worker’s creed Within the overall structure of a project there is always room for in- dividuality and craftsmanship. This is particularly true given the cur- rent state of software engineering. One hundred years from now, our engineering may seem as archaic as the techniques used by medieval Prepared exclusively for Zach P REFACE xxi cathedral builders seem to today’s civil engineers, while our craftsman- ship will still be honored. It’s a Continuous Process A tourist visiting England’s Eton College asked the gardener how he got the lawns so perfect. “That’s easy,” he replied, “You just brush off the dew every morning, mow them every other day, and roll them once a week.” “Is that all?” asked the tourist. “Absolutely,” replied the gardener. “Do that for 500 years and you’ll have a nice lawn, too.” Great lawns need small amounts of daily care, and so do great pro- grammers. Management consultants like to drop the word kaizen in conversations. “Kaizen” is a Japanese term that captures the concept of continuously making many small improvements. It was considered to be one of the main reasons for the dramatic gains in productivity and quality in Japanese manufacturing and was widely copied throughout the world. Kaizen applies to individuals, too. Every day, work to reﬁne the skills you have and to add new tools to your repertoire. Unlike the Eton lawns, you’ll start seeing results in a matter of days. Over the years, you’ll be amazed at how your experience has blossomed and your skills have grown. How the Book Is Organized This book is written as a collection of short sections. Each section is self-contained, and addresses a particular topic. You’ll ﬁnd numerous cross references, which help put each topic in context. Feel free to read the sections in any order—this isn’t a book you need to read front-to- back. Occasionally you’ll come across a box labeled Tip nn (such as Tip 1, “Care About Your Craft” on page xix). As well as emphasizing points in the text, we feel the tips have a life of their own—we live by them daily. You’ll ﬁnd a summary of all the tips on a pull-out card inside the back cover. Prepared exclusively for Zach xxii P REFACE Appendix A contains a set of resources: the book’s bibliography, a list of URLs to Web resources, and a list of recommended periodicals, books, and professional organizations. Throughout the book you’ll ﬁnd refer- ences to the bibliography and to the list of URLs—such as [KP99] and [URL 18], respectively. We’ve included exercises and challenges where appropriate. Exercises normally have relatively straightforward answers, while the challenges are more open-ended. To give you an idea of our thinking, we’ve in- cluded our answers to the exercises in Appendix B, but very few have a single correct solution. The challenges might form the basis of group discussions or essay work in advanced programming courses. What’s in a Name? “When I use a word,” Humpty Dumpty said, in rather a scornful tone, “it means just what I choose it to mean—neither more nor less.” Lewis Carroll, Through the Looking-Glass Scattered throughout the book you’ll ﬁnd various bits of jargon—either perfectly good English words that have been corrupted to mean some- thing technical, or horrendous made-up words that have been assigned meanings by computer scientists with a grudge against the language. The ﬁrst time we use each of these jargon words, we try to deﬁne it, or at least give a hint to its meaning. However, we’re sure that some have fallen through the cracks, and others, such as object and rela- tional database, are in common enough usage that adding a deﬁnition would be boring. If you do come across a term you haven’t seen be- fore, please don’t just skip over it. Take time to look it up, perhaps on the Web, or maybe in a computer science textbook. And, if you get a chance, drop us an e-mail and complain, so we can add a deﬁnition to the next edition. Having said all this, we decided to get revenge against the computer sci- entists. Sometimes, there are perfectly good jargon words for concepts, words that we’ve decided to ignore. Why? Because the existing jargon is normally restricted to a particular problem domain, or to a partic- ular phase of development. However, one of the basic philosophies of this book is that most of the techniques we’re recommending are uni- versal: modularity applies to code, designs, documentation, and team Prepared exclusively for Zach P REFACE xxiii organization, for instance. When we wanted to use the conventional jargon word in a broader context, it got confusing—we couldn’t seem to overcome the baggage the original term brought with it. When this happened, we contributed to the decline of the language by inventing our own terms. Source Code and Other Resources Most of the code shown in this book is extracted from compilable source ﬁles, available for download from our Web site: www.pragmaticprogrammer.com There you’ll also ﬁnd links to resources we ﬁnd useful, along with updates to the book and news of other Pragmatic Programmer devel- opments. Send Us Feedback We’d appreciate hearing from you. Comments, suggestions, errors in the text, and problems in the examples are all welcome. E-mail us at [email protected] Acknowledgments When we started writing this book, we had no idea how much of a team effort it would end up being. Addison-Wesley has been brilliant, taking a couple of wet-behind-the- ears hackers and walking us through the whole book-production pro- cess, from idea to camera-ready copy. Many thanks to John Wait and Meera Ravindiran for their initial support, Mike Hendrickson, our enthusiastic editor (and a mean cover designer!), Lorraine Ferrier and John Fuller for their help with production, and the indefatigable Julie DeBaggis for keeping us all together. Then there were the reviewers: Greg Andress, Mark Cheers, Chris Clee- land, Alistair Cockburn, Ward Cunningham, Martin Fowler, Thanh T. Giang, Robert L. Glass, Scott Henninger, Michael Hunter, Brian Prepared exclusively for Zach xxiv P REFACE Kirby, John Lakos, Pete McBreen, Carey P. Morris, Jared Richardson, Kevin Ruland, Eric Starr, Eric Vought, Chris Van Wyk, and Deborra Zukowski. Without their careful comments and valuable insights, this book would be less readable, less accurate, and twice as long. Thank you all for your time and wisdom. The second printing of this book beneﬁted greatly from the eagle eyes of our readers. Many thanks to Brian Blank, Paul Boal, Tom Ekberg, Brent Fulgham, Louis Paul Hebert, Henk-Jan Olde Loohuis, Alan Lund, Gareth McCaughan, Yoshiki Shibata, and Volker Wurst, both for ﬁnd- ing the mistakes and for having the grace to point them out gently. Over the years, we have worked with a large number of progressive clients, where we gained and reﬁned the experience we write about here. Recently, we’ve been fortunate to work with Peter Gehrke on sev- eral large projects. His support and enthusiasm for our techniques are much appreciated. This book was produced using LATEX, pic, Perl, dvips, ghostview, ispell, GNU make, CVS, Emacs, XEmacs, EGCS, GCC, Java, iContract, and SmallEiffel, using the Bash and zsh shells under Linux. The stagger- ing thing is that all of this tremendous software is freely available. We owe a huge “thank you” to the thousands of Pragmatic Programmers worldwide who have contributed these and other works to us all. We’d particularly like to thank Reto Kramer for his help with iContract. Last, but in no way least, we owe a huge debt to our families. Not only have they put up with late night typing, huge telephone bills, and our permanent air of distraction, but they’ve had the grace to read what we’ve written, time after time. Thank you for letting us dream. Andy Hunt Dave Thomas Prepared exclusively for Zach Chapter 1 A Pragmatic Philosophy What distinguishes Pragmatic Programmers? We feel it’s an attitude, a style, a philosophy of approaching problems and their solutions. They think beyond the immediate problem, always trying to place it in its larger context, always trying to be aware of the bigger picture. After all, without this larger context, how can you be pragmatic? How can you make intelligent compromises and informed decisions? Another key to their success is that they take responsibility for every- thing they do, which we discuss in The Cat Ate My Source Code. Being responsible, Pragmatic Programmers won’t sit idly by and watch their projects fall apart through neglect. In Software Entropy, we tell you how to keep your projects pristine. Most people ﬁnd change difﬁcult to accept, sometimes for good reasons, sometimes because of plain old inertia. In Stone Soup and Boiled Frogs, we look at a strategy for instigating change and (in the interests of balance) present the cautionary tale of an amphibian that ignored the dangers of gradual change. One of the beneﬁts of understanding the context in which you work is that it becomes easier to know just how good your software has to be. Sometimes near-perfection is the only option, but often there are trade-offs involved. We explore this in Good-Enough Software. Of course, you need to have a broad base of knowledge and experience to pull all of this off. Learning is a continuous and ongoing process. In Your Knowledge Portfolio, we discuss some strategies for keeping the momentum up. 1 Prepared exclusively for Zach 2 C HAPTER 1 A P RAGMATIC P HILOSOPHY Finally, none of us works in a vacuum. We all spend a large amount of time interacting with others. Communicate! lists ways we can do this better. Pragmatic programming stems from a philosophy of pragmatic think- ing. This chapter sets the basis for that philosophy. 1 The Cat Ate My Source Code The greatest of all weaknesses is the fear of appearing weak. J. B. Bossuet, Politics from Holy Writ, 1709 One of the cornerstones of the pragmatic philosophy is the idea of tak- ing responsibility for yourself and your actions in terms of your career advancement, your project, and your day-to-day work. A Pragmatic Pro- grammer takes charge of his or her own career, and isn’t afraid to admit ignorance or error. It’s not the most pleasant aspect of programming, to be sure, but it will happen—even on the best of projects. Despite thorough testing, good documentation, and solid automation, things go wrong. Deliveries are late. Unforeseen technical problems come up. These things happen, and we try to deal with them as professionally as we can. This means being honest and direct. We can be proud of our abilities, but we must be honest about our shortcomings—our igno- rance as well as our mistakes. Take Responsibility Responsibility is something you actively agree to. You make a commit- ment to ensure that something is done right, but you don’t necessarily have direct control over every aspect of it. In addition to doing your own personal best, you must analyze the situation for risks that are beyond your control. You have the right not to take on a responsibility for an impossible situation, or one in which the risks are too great. You’ll have to make the call based on your own ethics and judgment. When you do accept the responsibility for an outcome, you should ex- pect to be held accountable for it. When you make a mistake (as we all do) or an error in judgment, admit it honestly and try to offer options. Prepared exclusively for Zach T HE C AT A TE M Y S OURCE C ODE 3 Don’t blame someone or something else, or make up an excuse. Don’t blame all the problems on a vendor, a programming language, manage- ment, or your coworkers. Any and all of these may play a role, but it is up to you to provide solutions, not excuses. If there was a risk that the vendor wouldn’t come through for you, then you should have had a contingency plan. If the disk crashes—taking all of your source code with it—and you don’t have a backup, it’s your fault. Telling your boss “the cat ate my source code” just won’t cut it. TIP 3 Provide Options, Don’t Make Lame Excuses Before you approach anyone to tell them why something can’t be done, is late, or is broken, stop and listen to yourself. Talk to the rubber duck on your monitor, or the cat. Does your excuse sound reasonable, or stupid? How’s it going to sound to your boss? Run through the conversation in your mind. What is the other person likely to say? Will they ask, “Have you tried this ” or “Didn’t you con- sider that?” How will you respond? Before you go and tell them the bad news, is there anything else you can try? Sometimes, you just know what they are going to say, so save them the trouble. Instead of excuses, provide options. Don’t say it can’t be done; explain what can be done to salvage the situation. Does code have to be thrown out? Educate them on the value of refactoring (see Refactoring, page 184). Do you need to spend time prototyping to determine the best way to proceed (see Prototypes and Post-it Notes, page 53)? Do you need to introduce better testing (see Code That’s Easy to Test, page 189, and Ruthless Testing, page 237) or automation (see Ubiquitous Automation, page 230) to prevent it from happening again? Perhaps you need ad- ditional resources. Don’t be afraid to ask, or to admit that you need help. Try to ﬂush out the lame excuses before voicing them aloud. If you must, tell your cat ﬁrst. After all, if little Tiddles is going to take the blame.... Prepared exclusively for Zach 4 C HAPTER 1 A P RAGMATIC P HILOSOPHY Related sections include: Prototypes and Post-it Notes, page 53 Refactoring, page 184 Code That’s Easy to Test, page 189 Ubiquitous Automation, page 230 Ruthless Testing, page 237 Challenges How do you react when someone—such as a bank teller, an auto mechanic, or a clerk—comes to you with a lame excuse? What do you think of them and their company as a result? 2 Software Entropy While software development is immune from almost all physical laws, entropy hits us hard. Entropy is a term from physics that refers to the amount of “disorder” in a system. Unfortunately, the laws of thermo- dynamics guarantee that the entropy in the universe tends toward a maximum. When disorder increases in software, programmers call it “software rot.” There are many factors that can contribute to software rot. The most important one seems to be the psychology, or culture, at work on a project. Even if you are a team of one, your project’s psychology can be a very delicate thing. Despite the best laid plans and the best peo- ple, a project can still experience ruin and decay during its lifetime. Yet there are other projects that, despite enormous difﬁculties and con- stant setbacks, successfully ﬁght nature’s tendency toward disorder and manage to come out pretty well. What makes the difference? In inner cities, some buildings are beautiful and clean, while others are rotting hulks. Why? Researchers in the ﬁeld of crime and urban decay discovered a fascinating trigger mechanism, one that very quickly turns a clean, intact, inhabited building into a smashed and abandoned derelict [WK82]. Prepared exclusively for Zach S OFTWARE E NTROPY 5 A broken window. One broken window, left unrepaired for any substantial length of time, instills in the inhabitants of the building a sense of abandonment—a sense that the powers that be don’t care about the building. So another window gets broken. People start littering. Grafﬁti appears. Serious structural damage begins. In a relatively short space of time, the build- ing becomes damaged beyond the owner’s desire to ﬁx it, and the sense of abandonment becomes reality. The “Broken Window Theory” has inspired police departments in New York and other major cities to crack down on the small stuff in order to keep out the big stuff. It works: keeping on top of broken windows, grafﬁti, and other small infractions has reduced the serious crime level. TIP 4 Don’t Live with Broken Windows Don’t leave “broken windows” (bad designs, wrong decisions, or poor code) unrepaired. Fix each one as soon as it is discovered. If there is insufﬁcient time to ﬁx it properly, then board it up. Perhaps you can comment out the offending code, or display a "Not Implemented" mes- sage, or substitute dummy data instead. Take some action to prevent further damage and to show that you’re on top of the situation. We’ve seen clean, functional systems deteriorate pretty quickly once windows start breaking. There are other factors that can contribute to software rot, and we’ll touch on some of them elsewhere, but neglect accelerates the rot faster than any other factor. You may be thinking that no one has the time to go around cleaning up all the broken glass of a project. If you continue to think like that, then you’d better plan on getting a dumpster, or moving to another neighborhood. Don’t let entropy win. Putting Out Fires By contrast, there’s the story of an obscenely rich acquaintance of Andy’s. His house was immaculate, beautiful, loaded with priceless antiques, objets d’art, and so on. One day, a tapestry that was hang- ing a little too close to his living room ﬁreplace caught on ﬁre. The ﬁre Prepared exclusively for Zach 6 C HAPTER 1 A P RAGMATIC P HILOSOPHY department rushed in to save the day—and his house. But before they dragged their big, dirty hoses into the house, they stopped—with the ﬁre raging—to roll out a mat between the front door and the source of the ﬁre. They didn’t want to mess up the carpet. A pretty extreme case, to be sure, but that’s the way it must be with software. One broken window—a badly designed piece of code, a poor management decision that the team must live with for the duration of the project—is all it takes to start the decline. If you ﬁnd yourself working on a project with quite a few broken windows, it’s all too easy to slip into the mindset of “All the rest of this code is crap, I’ll just follow suit.” It doesn’t matter if the project has been ﬁne up to this point. In the original experiment leading to the “Broken Window Theory,” an abandoned car sat for a week untouched. But once a single window was broken, the car was stripped and turned upside down within hours. By the same token, if you ﬁnd yourself on a team and a project where the code is pristinely beautiful—cleanly written, well designed, and elegant—you will likely take extra special care not to mess it up, just like the ﬁreﬁghters. Even if there’s a ﬁre raging (deadline, release date, trade show demo, etc.), you don’t want to be the ﬁrst one to make a mess. Related sections include: Stone Soup and Boiled Frogs, page 7 Refactoring, page 184 Pragmatic Teams, page 224 Challenges Help strengthen your team by surveying your computing “neighborhood.” Choose two or three “broken windows” and discuss with your colleagues what the problems are and what could be done to ﬁx them. Can you tell when a window ﬁrst gets broken? What is your reaction? If it was the result of someone else’s decision, or a management edict, what can you do about it? Prepared exclusively for Zach S TONE S OUP AND B OILED F ROGS 7 3 Stone Soup and Boiled Frogs The three soldiers returning home from war were hungry. When they saw the village ahead their spirits lifted—they were sure the villagers would give them a meal. But when they got there, they found the doors locked and the windows closed. After many years of war, the villagers were short of food, and hoarded what they had. Undeterred, the soldiers boiled a pot of water and carefully placed three stones into it. The amazed villagers came out to watch. “This is stone soup,” the soldiers explained. “Is that all you put in it?” asked the villagers. “Absolutely—although some say it tastes even better with a few carrots.” A villager ran off, returning in no time with a basket of carrots from his hoard. A couple of minutes later, the villagers again asked “Is that it?” “Well,” said the soldiers, “a couple of potatoes give it body.” Off ran another villager. Over the next hour, the soldiers listed more ingredients that would enhance the soup: beef, leeks, salt, and herbs. Each time a different villager would run off to raid their personal stores. Eventually they had produced a large pot of steaming soup. The soldiers removed the stones, and they sat down with the entire village to enjoy the ﬁrst square meal any of them had eaten in months. There are a couple of morals in the stone soup story. The villagers are tricked by the soldiers, who use the villagers’ curiosity to get food from them. But more importantly, the soldiers act as a catalyst, bringing the village together so they can jointly produce something that they couldn’t have done by themselves—a synergistic result. Eventually ev- eryone wins. Every now and then, you might want to emulate the soldiers. You may be in a situation where you know exactly what needs doing and how to do it. The entire system just appears before your eyes—you know it’s right. But ask permission to tackle the whole thing and you’ll be met with delays and blank stares. People will form committees, bud- gets will need approval, and things will get complicated. Everyone will guard their own resources. Sometimes this is called “start-up fatigue.” Prepared exclusively for Zach 8 C HAPTER 1 A P RAGMATIC P HILOSOPHY It’s time to bring out the stones. Work out what you can reasonably ask for. Develop it well. Once you’ve got it, show people, and let them marvel. Then say “of course, it would be better if we added.” Pretend it’s not important. Sit back and wait for them to start asking you to add the functionality you originally wanted. People ﬁnd it easier to join an ongoing success. Show them a glimpse of the future and you’ll get them to rally around.1 TIP 5 Be a Catalyst for Change The Villagers’ Side On the other hand, the stone soup story is also about gentle and grad- ual deception. It’s about focusing too tightly. The villagers think about the stones and forget about the rest of the world. We all fall for it, every day. Things just creep up on us. We’ve all seen the symptoms. Projects slowly and inexorably get totally out of hand. Most software disasters start out too small to notice, and most project overruns happen a day at a time. Systems drift from their speciﬁcations feature by feature, while patch after patch gets added to a piece of code until there’s nothing of the original left. It’s often the accumulation of small things that breaks morale and teams. TIP 6 Remember the Big Picture We’ve never tried this—honest. But they say that if you take a frog and drop it into boiling water, it will jump straight back out again. However, if you place the frog in a pan of cold water, then gradually heat it, the frog won’t notice the slow increase in temperature and will stay put until cooked. 1. While doing this, you may be comforted by the line attributed to Rear Admiral Dr. Grace Hopper: “It’s easier to ask forgiveness than it is to get permission.” Prepared exclusively for Zach G OOD -E NOUGH S OFTWARE 9 Note that the frog’s problem is different from the broken windows issue discussed in Section 2. In the Broken Window Theory, people lose the will to ﬁght entropy because they perceive that no one else cares. The frog just doesn’t notice the change. Don’t be like the frog. Keep an eye on the big picture. Constantly review what’s happening around you, not just what you personally are doing. Related sections include: Software Entropy, page 4 Programming by Coincidence, page 172 Refactoring, page 184 The Requirements Pit, page 202 Pragmatic Teams, page 224 Challenges While reviewing a draft of this book, John Lakos raised the following is- sue: The soldiers progressively deceive the villagers, but the change they catalyze does them all good. However, by progressively deceiving the frog, you’re doing it harm. Can you determine whether you’re making stone soup or frog soup when you try to catalyze change? Is the decision subjec- tive or objective? 4 Good-Enough Software Striving to better, oft we mar what’s well. King Lear 1.4 There’s an old(ish) joke about a U.S. company that places an order for 100,000 integrated circuits with a Japanese manufacturer. Part of the speciﬁcation was the defect rate: one chip in 10,000. A few weeks later the order arrived: one large box containing thousands of ICs, and a small one containing just ten. Attached to the small box was a label that read: “These are the faulty ones.” Prepared exclusively for Zach 10 C HAPTER 1 A P RAGMATIC P HILOSOPHY If only we really had this kind of control over quality. But the real world just won’t let us produce much that’s truly perfect, particularly not bug-free software. Time, technology, and temperament all conspire against us. However, this doesn’t have to be frustrating. As Ed Yourdon described in an article in IEEE Software [You95], you can discipline yourself to write software that’s good enough—good enough for your users, for fu- ture maintainers, for your own peace of mind. You’ll ﬁnd that you are more productive and your users are happier. And you may well ﬁnd that your programs are actually better for their shorter incubation. Before we go any further, we need to qualify what we’re about to say. The phrase “good enough” does not imply sloppy or poorly produced code. All systems must meet their users’ requirements to be success- ful. We are simply advocating that users be given an opportunity to participate in the process of deciding when what you’ve produced is good enough. Involve Your Users in the Trade-Off Normally you’re writing software for other people. Often you’ll remem- ber to get requirements from them.2 But how often do you ask them how good they want their software to be? Sometimes there’ll be no choice. If you’re working on pacemakers, the space shuttle, or a low- level library that will be widely disseminated, the requirements will be more stringent and your options more limited. However, if you’re working on a brand new product, you’ll have different constraints. The marketing people will have promises to keep, the eventual end users may have made plans based on a delivery schedule, and your company will certainly have cash-ﬂow constraints. It would be unprofessional to ignore these users’ requirements simply to add new features to the pro- gram, or to polish up the code just one more time. We’re not advocating panic: it is equally unprofessional to promise impossible time scales and to cut basic engineering corners to meet a deadline. 2. That was supposed to be a joke! Prepared exclusively for Zach G OOD -E NOUGH S OFTWARE 11 The scope and quality of the system you produce should be speciﬁed as part of that system’s requirements. TIP 7 Make Quality a Requirements Issue Often you’ll be in situations where trade-offs are involved. Surprisingly, many users would rather use software with some rough edges today than wait a year for the multimedia version. Many IT departments with tight budgets would agree. Great software today is often preferable to perfect software tomorrow. If you give your users something to play with early, their feedback will often lead you to a better eventual solution (see Tracer Bullets, page 48). Know When to Stop In some ways, programming is like painting. You start with a blank canvas and certain basic raw materials. You use a combination of sci- ence, art, and craft to determine what to do with them. You sketch out an overall shape, paint the underlying environment, then ﬁll in the details. You constantly step back with a critical eye to view what you’ve done. Every now and then you’ll throw a canvas away and start again. But artists will tell you that all the hard work is ruined if you don’t know when to stop. If you add layer upon layer, detail over detail, the painting becomes lost in the paint. Don’t spoil a perfectly good program by overembellishment and over- reﬁnement. Move on, and let your code stand in its own right for a while. It may not be perfect. Don’t worry: it could never be perfect. (In Chapter 6, page 171, we’ll discuss philosophies for developing code in an imperfect world.) Related sections include: Tracer Bullets, page 48 The Requirements Pit, page 202 Pragmatic Teams, page 224 Great Expectations, page 255 Prepared exclusively for Zach 12 C HAPTER 1 A P RAGMATIC P HILOSOPHY Challenges Look at the manufacturers of the software tools and operating systems that you use. Can you ﬁnd any evidence that these companies are comfortable shipping software they know is not perfect? As a user, would you rather (1) wait for them to get all the bugs out, (2) have complex software and accept some bugs, or (3) opt for simpler software with fewer defects? Consider the effect of modularization on the delivery of software. Will it take more or less time to get a monolithic block of software to the required quality compared with a system designed in modules? Can you ﬁnd com- mercial examples? 5 Your Knowledge Portfolio An investment in knowledge always pays the best interest. Benjamin Franklin Ah, good old Ben Franklin—never at a loss for a pithy homily. Why, if we could just be early to bed and early to rise, we’d be great programmers— right? The early bird might get the worm, but what happens to the early worm? In this case, though, Ben really hit the nail on the head. Your knowledge and experience are your most important professional assets. Unfortunately, they’re expiring assets.3 Your knowledge becomes out of date as new techniques, languages, and environments are developed. Changing market forces may render your experience obsolete or irrele- vant. Given the speed at which Web-years ﬂy by, this can happen pretty quickly. As the value of your knowledge declines, so does your value to your company or client. We want to prevent this from ever happening. 3. An expiring asset is something whose value diminishes over time. Examples include a warehouse full of bananas and a ticket to a ball game. Prepared exclusively for Zach Y OUR K NOWLEDGE P OR TFOLIO 13 Your Knowledge Portfolio We like to think of all the facts programmers know about computing, the application domains they work in, and all their experience as their Knowledge Portfolios. Managing a knowledge portfolio is very similar to managing a ﬁnancial portfolio: 1. Serious investors invest regularly—as a habit. 2. Diversiﬁcation is the key to long-term success. 3. Smart investors balance their portfolios between conservative and high-risk, high-reward investments. 4. Investors try to buy low and sell high for maximum return. 5. Portfolios should be reviewed and rebalanced periodically. To be successful in your career, you must manage your knowledge port- folio using these same guidelines. Building Your Portfolio Invest regularly. Just as in ﬁnancial investing, you must invest in your knowledge portfolio regularly. Even if it’s just a small amount, the habit itself is as important as the sums. A few sample goals are listed in the next section. Diversify. The more different things you know, the more valuable you are. As a baseline, you need to know the ins and outs of the particular technology you are working with currently. But don’t stop there. The face of computing changes rapidly—hot technology today may well be close to useless (or at least not in demand) to- morrow. The more technologies you are comfortable with, the better you will be able to adjust to change. Manage risk. Technology exists along a spectrum from risky, potentially high-reward to low-risk, low-reward standards. It’s not a good idea to invest all of your money in high-risk stocks that might collapse suddenly, nor should you invest all of it conserva- tively and miss out on possible opportunities. Don’t put all your technical eggs in one basket. Prepared exclusively for Zach 14 C HAPTER 1 A P RAGMATIC P HILOSOPHY Buy low, sell high. Learning an emerging technology before it be- comes popular can be just as hard as ﬁnding an undervalued stock, but the payoff can be just as rewarding. Learning Java when it ﬁrst came out may have been risky, but it paid off handsomely for the early adopters who are now at the top of that ﬁeld. Review and rebalance. This is a very dynamic industry. That hot technology you started investigating last month might be stone cold by now. Maybe you need to brush up on that database technology that you haven’t used in a while. Or perhaps you could be bet- ter positioned for that new job opening if you tried out that other language.... Of all these guidelines, the most important one is the simplest to do: TIP 8 Invest Regularly in Your Knowledge Portfolio Goals Now that you have some guidelines on what and when to add to your knowledge portfolio, what’s the best way to go about acquiring intellec- tual capital with which to fund your portfolio? Here are a few sugges- tions. Learn at least one new language every year. Different languages solve the same problems in different ways. By learning several dif- ferent approaches, you can help broaden your thinking and avoid getting stuck in a rut. Additionally, learning many languages is far easier now, thanks to the wealth of freely available software on the Internet (see page 267). Read a technical book each quarter. Bookstores are full of techni- cal books on interesting topics related to your current project. Once you’re in the habit, read a book a month. After you’ve mastered the technologies you’re currently using, branch out and study some that don’t relate to your project. Read nontechnical books, too. It is important to remember that computers are used by people—people whose needs you are trying to satisfy. Don’t forget the human side of the equation. Prepared exclusively for Zach Y OUR K NOWLEDGE P OR TFOLIO 15 Take classes. Look for interesting courses at your local commu- nity college or university, or perhaps at the next trade show that comes to town. Participate in local user groups. Don’t just go and listen, but actively participate. Isolation can be deadly to your career; ﬁnd out what people are working on outside of your company. Experiment with different environments. If you’ve worked only in Windows, play with Unix at home (the freely available Linux is per- fect for this). If you’ve used only makefiles and an editor, try an IDE, and vice versa. Stay current. Subscribe to trade magazines and other journals (see page 262 for recommendations). Choose some that cover tech- nology different from that of your current project. Get wired. Want to know the ins and outs of a new language or other technology? Newsgroups are a great way to ﬁnd out what experiences other people are having with it, the particular jargon they use, and so on. Surf the Web for papers, commercial sites, and any other sources of information you can ﬁnd. It’s important to continue investing. Once you feel comfortable with some new language or bit of technology, move on. Learn another one. It doesn’t matter whether you ever use any of these technologies on a project, or even whether you put them on your resume. The process of learning will expand your thinking, opening you to new possibilities and new ways of doing things. The cross-pollination of ideas is important; try to apply the lessons you’ve learned to your current project. Even if your project doesn’t use that technology, perhaps you can borrow some ideas. Get familiar with object orientation, for instance, and you’ll write plain C programs differently. Opportunities for Learning So you’re reading voraciously, you’re on top of all the latest breaking developments in your ﬁeld (not an easy thing to do), and somebody asks you a question. You don’t have the faintest idea what the answer is, and freely admit as much. Prepared exclusively for Zach 16 C HAPTER 1 A P RAGMATIC P HILOSOPHY Don’t let it stop there. Take it as a personal challenge to ﬁnd the answer. Ask a guru. (If you don’t have a guru in your ofﬁce, you should be able to ﬁnd one on the Internet: see the box on on the facing page.) Search the Web. Go to the library.4 If you can’t ﬁnd the answer yourself, ﬁnd out who can. Don’t let it rest. Talking to other people will help build your personal network, and you may surprise yourself by ﬁnding solutions to other, unrelated problems along the way. And that old portfolio just keeps getting bigger.... All of this reading and researching takes time, and time is already in short supply. So you need to plan ahead. Always have something to read in an otherwise dead moment. Time spent waiting for doctors and dentists can be a great opportunity to catch up on your reading—but be sure to bring your own magazine with you, or you might ﬁnd yourself thumbing through a dog-eared 1973 article about Papua New Guinea. Critical Thinking The last important point is to think critically about what you read and hear. You need to ensure that the knowledge in your portfolio is accurate and unswayed by either vendor or media hype. Beware of the zealots who insist that their dogma provides the only answer—it may or may not be applicable to you and your project. Never underestimate the power of commercialism. Just because a Web search engine lists a hit ﬁrst doesn’t mean that it’s the best match; the content provider can pay to get top billing. Just because a bookstore features a book prominently doesn’t mean it’s a good book, or even popular; they may have been paid to place it there. TIP 9 Critically Analyze What You Read and Hear Unfortunately, there are very few simple answers anymore. But with your extensive portfolio, and by applying some critical analysis to the 4. In this era of the Web, many people seem to have forgotten about real live libraries ﬁlled with research material and staff. Prepared exclusively for Zach Y OUR K NOWLEDGE P OR TFOLIO 17 Care and Cultivation of Gurus With the global adoption of the Internet, gurus suddenly are as close as your Enter key. So, how do you ﬁnd one, and how do you get one to talk with you? We ﬁnd there are some simple tricks. Know exactly what you want to ask, and be as speciﬁc as you can be. Frame your question carefully and politely. Remember that you’re asking a favor; don’t seem to be demanding an answer. Once you’ve framed your question, stop and look again for the answer. Pick out some keywords and search the Web. Look for appropriate FAQs (lists of frequently asked questions with an- swers). Decide if you want to ask publicly or privately. Usenet news- groups are wonderful meeting places for experts on just about any topic, but some people are wary of these groups’ public nature. Alternatively, you can always e-mail your guru directly. Either way, use a meaningful subject line. (“Need Help!!!” doesn’t cut it.) Sit back and be patient. People are busy, and it may take days to get a speciﬁc answer. Finally, please be sure to thank anyone who responds to you. And if you see people asking questions you can answer, play your part and participate. torrent of technical publications you will read, you can understand the complex answers. Challenges Start learning a new language this week. Always programmed in C++? Try Smalltalk [URL 13] or Squeak [URL 14]. Doing Java? Try Eiffel [URL 10] or TOM [URL 15]. See page 267 for sources of other free compilers and environments. Start reading a new book (but ﬁnish this one ﬁrst!). If you are doing very detailed implementation and coding, read a book on design and architec- ture. If you are doing high-level design, read a book on coding techniques. Prepared exclusively for Zach 18 C HAPTER 1 A P RAGMATIC P HILOSOPHY Get out and talk technology with people who aren’t involved in your cur- rent project, or who don’t work for the same company. Network in your company cafeteria, or maybe seek out fellow enthusiasts at a local user’s group meeting. 6 Communicate! I believe that it is better to be looked over than it is to be overlooked. Mae West, Belle of the Nineties, 1934 Maybe we can learn a lesson from Ms. West. It’s not just what you’ve got, but also how you package it. Having the best ideas, the ﬁnest code, or the most pragmatic thinking is ultimately sterile unless you can com- municate with other people. A good idea is an orphan without effective communication. As developers, we have to communicate on many levels. We spend hours in meetings, listening and talking. We work with end users, trying to understand their needs. We write code, which communicates our intentions to a machine and documents our thinking for future generations of developers. We write proposals and memos requesting and justifying resources, reporting our status, and suggesting new approaches. And we work daily within our teams to advocate our ideas, modify existing practices, and suggest new ones. A large part of our day is spent communicating, so we need to do it well. We’ve put together a list of ideas that we ﬁnd useful. Know What You Want to Say Probably the most difﬁcult part of the more formal styles of commu- nication used in business is working out exactly what it is you want to say. Fiction writers plot out their books in detail before they start, but people writing technical documents are often happy to sit down at a keyboard, enter “1. Introduction,” and start typing whatever comes into their heads next. Plan what you want to say. Write an outline. Then ask yourself, “Does this get across whatever I’m trying to say?” Reﬁne it until it does. Prepared exclusively for Zach C OMMUNICATE ! 19 This approach is not just applicable to writing documents. When you’re faced with an important meeting or a phone call with a major client, jot down the ideas you want to communicate, and plan a couple of strategies for getting them across. Know Your Audience You’re communicating only if you’re conveying information. To do that, you need to understand the needs, interests, and capabilities of your audience. We’ve all sat in meetings where a development geek glazes over the eyes of the vice president of marketing with a long monologue on the merits of some arcane technology. This isn’t communicating: it’s just talking, and it’s annoying.5 Form a strong mental picture of your audience. The acrostic WISDOM, shown in Figure 1.1 on the following page, may help. Say you want to suggest a Web-based system to allow your end users to submit bug reports. You can present this system in many differ- ent ways, depending on your audience. End users will appreciate that they can submit bug reports 24 hours a day without waiting on the phone. Your marketing department will be able to use this fact to boost sales. Managers in the support department will have two reasons to be happy: fewer staff will be needed, and problem reporting will be automated. Finally, developers may enjoy getting experience with Web- based client-server technologies and a new database engine. By making the appropriate pitch to each group, you’ll get them all excited about your project. Choose Your Moment It’s six o’clock on Friday afternoon, following a week when the auditors have been in. Your boss’s youngest is in the hospital, it’s pouring rain outside, and the commute home is guaranteed to be a nightmare. This probably isn’t a good time to ask her for a memory upgrade for your PC. As part of understanding what your audience needs to hear, you need to work out what their priorities are. Catch a manager who’s just been given a hard time by her boss because some source code got lost, and 5. The word annoy comes from the Old French enui, which also means “to bore.” Prepared exclusively for Zach 20 C HAPTER 1 A P RAGMATIC P HILOSOPHY Figure 1.1. The WISDOM acrostic—understanding an audience What do you want them to learn? What is their interest in what you’ve got to say? How sophisticated are they? How much detail do they want? Whom do you want to own the information? How can you motivate them to listen to you? you’ll have a more receptive listener to your ideas on source code repos- itories. Make what you’re saying relevant in time, as well as in content. Sometimes all it takes is the simple question “Is this a good time to talk about...?” Choose a Style Adjust the style of your delivery to suit your audience. Some people want a formal “just the facts” brieﬁng. Others like a long, wide-ranging chat before getting down to business. When it comes to written docu- ments, some like to receive large bound reports, while others expect a simple memo or e-mail. If in doubt, ask. Remember, however, that you are half of the communication transac- tion. If someone says they need a paragraph describing something and you can’t see any way of doing it in less than several pages, tell them so. Remember, that kind of feedback is a form of communication, too. Make It Look Good Your ideas are important. They deserve a good-looking vehicle to convey them to your audience. Too many developers (and their managers) concentrate solely on con- tent when producing written documents. We think this is a mistake. Any chef will tell you that you can slave in the kitchen for hours only to ruin your efforts with poor presentation. There is no excuse today for producing poor-looking printed docu- ments. Modern word processors (along with layout systems such as LATEX and troff) can produce stunning output. You need to learn just a few basic commands. If your word processor supports style sheets, use Prepared exclusively for Zach C OMMUNICATE ! 21 them. (Your company may already have deﬁned style sheets that you can use.) Learn how to set page headers and footers. Look at the sam- ple documents included with your package to get ideas on style and layout. Check the spelling, ﬁrst automatically and then by hand. After awl, their are spelling miss steaks that the chequer can knot ketch. Involve Your Audience We often ﬁnd that the documents we produce end up being less im- portant than the process we go through to produce them. If possible, involve your readers with early drafts of your document. Get their feed- back, and pick their brains. You’ll build a good working relationship, and you’ll probably produce a better document in the process. Be a Listener There’s one technique that you must use if you want people to listen to you: listen to them. Even if this is a situation where you have all the information, even if this is a formal meeting with you standing in front of 20 suits—if you don’t listen to them, they won’t listen to you. Encourage people to talk by asking questions, or have them summarize what you tell them. Turn the meeting into a dialog, and you’ll make your point more effectively. Who knows, you might even learn some- thing. Get Back to People If you ask someone a question, you feel they’re impolite if they don’t respond. But how often do you fail to get back to people when they send you an e-mail or a memo asking for information or requesting some action? In the rush of everyday life, it’s easy to forget. Always respond to e-mails and voice mails, even if the response is simply “I’ll get back to you later.” Keeping people informed makes them far more forgiving of the occasional slip, and makes them feel that you haven’t forgotten them. TIP 10 It’s Both What You Say and the Way You Say It Unless you work in a vacuum, you need to be able to communicate. The more effective that communication, the more inﬂuential you become. Prepared exclusively for Zach 22 C HAPTER 1 A P RAGMATIC P HILOSOPHY E-Mail Communication Everything we’ve said about communicating in writing applies equally to electronic mail. E-mail has evolved to the point where it is a main- stay of intra- and intercorporate communications. E-mail is used to discuss contracts, to settle disputes, and as evidence in court. But for some reason, people who would never send out a shabby paper document are happy to ﬂing nasty-looking e-mail around the world. Our e-mail tips are simple: Proofread before you hit SEND. Check the spelling. Keep the format simple. Some people read e-mail using propor- tional fonts, so the ASCII art pictures you laboriously created will look to them like hen-scratchings. Use rich-text or HTML formatted mail only if you know that all your recipients can read it. Plain text is universal. Try to keep quoting to a minimum. No one likes to receive back their own 100-line e-mail with “I agree” tacked on. If you’re quoting other people’s e-mail, be sure to attribute it, and quote it inline (rather than as an attachment). Don’t ﬂame unless you want it to come back and haunt you later. Check your list of recipients before sending. A recent Wall Street Journal article described an employee who took to distributing criticisms of his boss over departmental e-mail, without realizing that his boss was included on the distribution list. Archive and organize your e-mail—both the important stuff you receive and the mail you send. As various Microsoft and Netscape employees discovered during the 1999 Department of Justice investigation, e-mail is forever. Try to give the same attention and care to e-mail as you would to any written memo or report. Prepared exclusively for Zach C OMMUNICATE ! 23 Summary Know what you want to say. Know your audience. Choose your moment. Choose a style. Make it look good. Involve your audience. Be a listener. Get back to people. Related sections include: Prototypes and Post-it Notes, page 53 Pragmatic Teams, page 224 Challenges There are several good books that contain sections on communications within development teams [Bro95, McC95, DL99]. Make it a point to try to read all three over the next 18 months. In addition, the book Dinosaur Brains [Ber96] discusses the emotional baggage we all bring to the work environment. The next time you have to give a presentation, or write a memo advocating some position, try working through the WISDOM acrostic on page 20 before you start. See if it helps you understand how to position what you say. If appropriate, talk to your audience afterward and see how accurate your assessment of their needs was. Prepared exclusively for Zach This page intentionally left blank Prepared exclusively for Zach Chapter 2 A Pragmatic Approach There are certain tips and tricks that apply at all levels of software development, ideas that are almost axiomatic, and processes that are virtually universal. However, these approaches are rarely documented as such; you’ll mostly ﬁnd them written down as odd sentences in dis- cussions of design, project management, or coding. In this chapter we’ll bring these ideas and processes together. The ﬁrst two sections, The Evils of Duplication and Orthogonality, are closely related. The ﬁrst warns you not to duplicate knowledge throughout your systems, the second not to split any one piece of knowledge across multiple system components. As the pace of change increases, it becomes harder and harder to keep our applications relevant. In Reversibility, we’ll look at some techniques that help insulate your projects from their changing environment. The next two sections are also related. In Tracer Bullets, we talk about a style of development that allows you to gather requirements, test designs, and implement code at the same time. If this

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