400+ Thought-Provoking Software Engineering Quotes

Sometimes a short thought can bring amazing ideas. There are some great quotes I’ve been collecting. I use them as inspiration or motto for some articles. You will find the links below. There are only two hard things in Computer Science: cache invalidation and naming things. Phil Karlton What exactly is a name — Part I The Quest Code Smell 49 - Caches Make illegal states unrepresentable. Yaron Minsky The Evil Power of Mutants First make the change easy (warning: this might be hard), then make the easy change. Kent Beck Code Smell 35 - State as Properties Object-oriented programming languages support encapsulation, thereby improving the ability of software to be reused, refined, tested, maintained, and extended. The full benefit of this support can only be realized if encapsulation is maximized during the design process. Rebecca Wirfs-Brock Code Smell 28 - Setters Don’t automate an undisciplined workflow. The computer won’t solve what the customer’s management can’t. Larry Bernstein Science is what we understand well enough to explain to a computer. Art is everything else we do. Donald Knuth Voluminous documentation is part of the problem, not part of the solution. Tom DeMarco Before you use a method in a legacy system, check to see if there are tests for it. If there aren’t, write them. When you do this consistently, you use tests as a medium of communication. Michael Feathers The biggest issue on software teams is making sure everyone understands what everyone else is doing. Martin Fowler A programming language is a tool that has a profound influence on our thinking habits. Edsger Dijkstra Object thinking focuses our attention on the problem space rather than the solution space. David West The essence of XML is this: the problem it solves is not hard, and it does not solve the problem well. Phil Wadler Software is like entropy: It is difficult to grasp, weighs nothing, and obeys the Second Law of Thermodynamics; i.e., it always increases. Norman Augustine The key to performance is elegance, not battalions of special cases. Jon Bentley and Douglas McIlroy We comfort ourselves with the belief that if the customers had just been happy with what they said they needed, the design would have been fine. It’s the customer’s fault for changing the requirements on us. Robert Martin PHP is a minor evil perpetrated and created by incompetent amateurs, whereas Perl is a great and insidious evil, perpetrated by skilled but perverted professionals. Jon Ribbens At any particular point in time, the features provided by our programming languages reflect our understanding of software and programming. R. E. Fairley Programming isn't about what you know; it's about what you can figure out. Chris Pine In general, the longer you wait before fixing a bug, the costlier (in time and money) it is to fix. Joel Spolsky Nothing is harder than working under a tight deadline and still taking the time to clean up as you go. Kent Beck Code Smell 109 - Automatic Properties When I’m studying code, refactoring leads me to higher levels of understanding that I would otherwise miss. Those who dismiss comprehension refactoring as useless fiddling with the code don’t realize they never see the opportunities hidden behind the confusion. Martin Fowler The best way to start fixing a bug is to make it reproducible. After all, if you can’t reproduce it, how will you know if it is ever fixed? Andrew Hunt A computer once beat me at chess, but it was no match for me at kick boxing. Emo Philips Later Equals Never. LeBlanc's Law People think that computer science is the art of geniuses but the actual reality is the opposite, just many people doing things that build on each other, like a wall of mini stones. Donald Knuth Your most unhappy customers are your greatest source of learning. Bill Gates The danger from computers is not that they will eventually get as smart as men, but that we will meanwhile agree to meet them halfway. Bernard Avishai In programming, if someone tells you “you’re overcomplicating it,” they’re either 10 steps behind you or 10 steps ahead of you. Andrew Clark The only truly secure system is one that is powered off, cast in a block of concrete and sealed in a lead-lined room with armed guards. Gene Spafford It's not at all important to get it right the first time. It's vitally important to get it right the last time. Andrew Hunt Sometimes it pays to stay in bed on Monday, rather than spending the rest of the week debugging Monday's code. Dan Salomon Weeks of programming can save you hours of planning. Anonymous It’s OK to figure out murder mysteries, but you shouldn’t need to figure out code. You should be able to read it. Steve McConnell Code Smell 74 - Empty Lines There is an art to knowing where things should be checked and making sure that the program fails fast if you make a mistake. That kind of choosing is part of the art of simplification. Ward Cunningham I've finally learned what 'upward compatible' means. It means we get to keep all our old mistakes. Dennie van Tassel Code Smell 104 - Assert True The software isn’t finished until the last user is dead. Sidney Markowitz An error arises from treating object variables (instance variables) as if they were data attributes and then creating your hierarchy based on shared attributes. Always create hierarchies based on shared behaviors, side. David West Information shared by an object might or might not be part of the structure of that object. That is, the object might compute the information, or it might delegate the request for information to another object. Rebecca Wirfs Brooks The cheapest, fastest and most reliable components of a computer system are those that aren’t there. Gordon Bell You can prove anything by mentioning another computer language. Larry Wall Your obligation is that of active participation. You should not act as knowledge-absorbing sponges, but as whetstones on which we can all sharpen our wits. Edsger W. Dijkstra Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning. Rick Cook Code Smell 84 - Max Min (Javascript) Without requirements or design, programming is the art of adding bugs to an empty text file. Louis Srygley Encapsulate the concept that varies. Erich Gamma Code Smell 103 - Double Encapsulation Good programmers never write what they can steal or borrow. Jeff Atwood It is very hard to predict, especially the future. Niels Bohr Code Smell 54 - Anchor Boats You cannot teach beginners top-down programming, because they don't know which end is up. Tony Hoare Duplication is far cheaper than the wrong abstraction. Sandi Metz Learn not to add too many features right away, and get the core idea built and tested. Leah Culver If it doesn’t work, it doesn’t matter how fast it doesn’t work. Mich Ravera Code Smell 101 - Comparison Against Booleans Writing a class without its contract would be similar to producing an engineering component (electrical circuit, VLSI (Very Large Scale Integration) chip, bridge, engine...) without a spec. No professional engineer would even consider the idea. Bertrand Meyer Telling a programmer there's already a library to do X is like telling a songwriter there's already a song about love. Pete Cordell A cache with a bad policy is another name for a memory leak. Rico Mariani In a purely functional program, the value of a [constant] never changes, and yet, it changes all the time! A paradox! Joel Spolsky Code Smell 02 - Constants and Magic Numbers If you lie to the compiler, it will get its revenge. Henry Spencer Code Smell 62 - Flag Variables When your code depends on an interface, that dependency is usually very minor and unobtrusive. Your code doesn’t have to change unless the interface changes, and interfaces typically change far less often than the code behind them. When you have an interface, you can edit classes that implement that interface or add new classes that implement the interface, all without impacting code that uses the interface. For this reason, it is better to depend on interfaces or abstract classes than it is to depend on concrete classes. When you depend on less volatile things, you minimize the chance that particular changes will trigger massive recompilation. Michael Feathers Code Smell 61 - Coupling to Classes Never spend 6 minutes doing something by hand when you can spend 6 hours failing to automate it. Zhuowei Zhang The value of a prototype is in the education it gives you, not in the code itself. Alan Cooper Code Smell 68 - Getters When someone says, "I want a programming language in which I need only say what I want done," give him a lollipop. Alan J. Perlis Changes in software design will eventually mean "one step forward, two steps back". It is inevitable. Salman Arshad The real hero of programming is the one who writes negative code. Douglas McIlroy Mathematicians stand on each others' shoulders and computer scientists stand on each others' toes. Richard Hamming The code you write makes you a programmer. The code you delete makes you a good one. The code you don't have to write makes you a great one. Mario Fusco Simple things should be simple, complex things should be possible. Alan Kay Code Smell 31 - Accidental Methods on Business Objects Final source code is the real software design. Jack Reeves Code Smell 99 - First Second If you think good architecture is expensive, try bad architecture. Brian Foote and Joseph Yoder The whole point of getting things done is knowing what to leave undone. Oswald Chambers Object-oriented programming increases the value of these metrics by managing this complexity. The most effective tool available for dealing with complexity is abstraction. Many types of abstraction can be used, but encapsulation is the main form of abstraction by which complexity is managed in object-oriented programming. Rebecca Wirfs-Brock Code Smell 21 - Anonymous Functions Abusers Make it correct, make it clear, make it concise, make it fast. In that order. Wes Dyer Indeed, the woes of Software Engineering are not due to lack of tools, or proper management, but largely due to lack of sufficient technical competence. Niklaus Wirth The last good thing written in C was Franz Schubert's Symphony Number 9. Erwin Dieterich There is absolutely no reason to make computers as stupid as people are. Nigel Jacob To me programming is more than an important practical art. It is also a gigantic undertaking in the foundations of knowledge. Grace Hopper The use of COBOL cripples the mind; its teaching should therefore be regarded as a criminal offense. Edsger Dijkstra Optimism is an occupational hazard of programming: feedback is the treatment. Kent Beck Hackers are arrogant geek romantics. They lack the attentive spirit of inquiry. Bruce Sterling Code Smell 44 - Magic Corrections If someone claims to have the perfect programming language, he is either a fool or a salesman or both. Bjarne Stroustrup Thinking is not the ability to manipulate language; it's the ability to manipulate concepts. Leslie Lamport If you can get today’s work done today, but you do it in such a way that you can’t possibly get tomorrow’s work done tomorrow, then you lose. Martin Fowler A computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are, in short, a perfect match. Bill Bryson Programming is not about typing, it's about thinking. Rich Hickey The most likely way for the world to be destroyed, most experts agree, is by accident. That's where we come in; we're computer professionals. We cause accidents. Nathaniel S. Borenstein There’s nothing more permanent than a temporary hack. Kyle Simpson Code Smell 27 - Associative Arrays The trouble with programmers is that you can never tell what a programmer is doing until it’s too late. Seymour Cray The primary disadvantage of Wrap Method is that it can lead to poor names. In the previous example, we renamed the pay method dispatchPay() just because we needed a different name for code in the original method. Michael Feathers Code Smell 59 - Basic Do Functions Learning to code is useful no matter what your career ambitions are. Arianna Huffington It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration. Edsger Dijkstra Code Smell 100 - GoTo Of course bad code can be cleaned up. But it’s very expensive. Robert C. Martin Blaming programmers has been the prevailing approach for a half century of software development: It has not solved the problem yet, so it is time to look in different directions. Boris Beizer 80 percent of my problems are simple logic errors. 80 percent of the remaining problems are pointer errors. The remaining problems are hard. Mark Donner The purpose of software engineering is to control complexity, not to create it. Pamela Zave Code Smell 102 - Arrow Code The purpose of computing is insight, not numbers. Richard Hamming Code Smell 71 - Magic Floats Disguised as Decimals Write shy code — modules that don't reveal anything unnecessary to other modules and that don't rely on other modules' implementations. Dave Thomas Code Smell 60 - Global Classes Software is a gas; it expands to fill its container. Nathan Myhrvold The trick is to fix the problem you have, rather than the problem you want. Bram Cohen Singleton - The root of all evil Software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification. Bertrand Meyer Software and cathedrals are much the same. First we build them, then we pray. Sam Redwine A design that doesn’t take change into account risks major redesign in the future. Erich Gamma Either way you look at it (DRY or laziness), the idea is the same: make your program flexible. When change comes (and it always does), you'll have a much easier time changing with it. Chris Pine Code Smell 83 - Variables Reassignment Duplication is the primary enemy of a well-designed system. Robert Martin Code Smell 66 - Shotgun Surgery Software is a gas; it expands to fill its container. Nathan Myhrvold Code Smell 43 - Concrete Classes Subclassified I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years. Tony Hoare Code Smell 12 - Null One bad programmer can easily create two new jobs a year. David Parnas Every great developer you know got there by solving problems they were unqualified to solve until they actually did it. Patrick McKenzie Simplicity is prerequisite for reliability. Edsger W. Dijkstra Good design adds value faster than it adds cost. Thomas C. Gale Types are essentially assertions about a program. And I think it’s valuable to have things be as absolutely simple as possible, including not even saying what the types are. Dan Ingalls Code Smell 65 - Variables Named after Types Some people are good programmers because they can handle many more details than most people. But there are a lot of disadvantages in selecting programmers for that reason — it can result in programs that no one else can maintain. Butler Lampson Before software can be reusable it first has to be usable. Ralph Johnson Copying skips understanding. Understanding is how you grow. You have to understand why something works or why something is how it is. When you copy it, you miss that. You just repurpose the last layer instead of understanding all the layers underneath. Jason Fried Most software today is very much like an Egyptian pyramid with millions of bricks piled on top of each other, with no structural integrity, but just done by brute force and thousands of slaves. Alan Kay Bugs are bugs. You write code with bugs because you do. If it’s a safe language in the sense of run-time safe, the operating system crashes instead of doing a buffer overflow in a way that’s exploitable. Ken Thompson Code Smell 111 - Modifying Collections While Traversing The Scrum idea of a separated Scrum Master is good for Scrum, but not appropriate for most projects. Good development requires not just talkers but doers. Bertrand Meyer Any sufficiently advanced bug is indistinguishable from a feature. Bruce Brown Premature optimization is the root of all evil Donald Knuth Code Smell 20 - Premature Optimization When in doubt, use brute force. Ken Thompson The main activity of programming is not the origination of new independent programs, but in the integration, modification, and explanation of existing ones. Terry Winograd Any problem in computer science can be solved with another level of indirection. David Wheeler Code Smell 50 - Object Keys Computer science is not about machines, in the same way that astronomy is not about telescopes. There is an essential unity of mathematics and computer science. Michael R. Fellows Code Smell 89 - Math Feature Envy There are two ways to write code: write code so simple there are obviously no bugs in it, or write code so complex that there are no obvious bugs in it. Tony Hoare Code Smell 78 - Callback Hell Let us change our traditional attitude to the construction of programs: Instead of imagining that our main task is to instruct a computer what to do, let us concentrate rather on explaining to human beings what we want a computer to do. Donald E. Knuth Code Smell 95 - Premature Classification Computer scientists have so far worked on developing powerful programming languages that make it possible to solve the technical problems of computation. Little effort has gone toward devising the languages of interaction. Don Norman When the final design seems too simple for the amount of work you've put in, then you know you're done. Brady Clark Developers are drawn to complexity like moths to a flame, frequently with the same result. Neal Ford We have persistant objects, they're called files. Ken Thompson I am not terribly dogmatical about the goto statement. I have the uncomfortable feeling that others are making a religion out of it, as if the conceptual problems of programming could be solved by a single trick, by a simple form of coding discipline! Edsger Dijkstra No amount of elegant programming or technology will solve a problem if it is improperly specified or understood to begin with. Milt Bryce Discovery consists of seeing what everyone else has seen and thinking what no one else has thought. Albert Szent-Gyorgi It should be noted that no ethically-trained software engineer would ever consent to write a DestroyBaghdad procedure. Basic professional ethics would instead require him to write a DestroyCity procedure, to which Baghdad could be given as a parameter. Nathaniel Borenstein So why was it so hard to tell a computer to do something only mildly complex? Well, it wasn't the "mildly complex" part that was giving me problems; it was the "tell a computer" part. Chris Pine There is no code so big, twisted, or complex that maintenance can't make it worse. Gerald M. Weinberg First think about what the ultimate would be. Then take a step away from that, and another, until you get something you can build. Matt Reedy You must have long-range goals to keep you from being frustrated by short-range failures. Charles C. Noble In programming, the hard part isn't solving problems, but deciding what problems to solve. Paul Graham Code Smell 39 - new Date() The key to efficient development is to make interesting new mistakes. Tom Love Walking on water and developing software from a specification are easy if both are frozen. Edward V Berard The Diagram is Not the Model. The model is not the diagram. It is an abstraction, a set of concepts and relationships between them. Eric Evans Code Smell 47 - Diagrams Eighty percent of all input forms ask questions they have no business asking. Mike Garey A primary cause of complexity is that software vendors uncritically adopt almost any feature that users want. Niklaus Wirth No crisis inside a computer is worth humiliating a human. Alan Cooper I love software, because if you can imagine something, you can build it. Ray Ozzie Beauty is more important in computing than anywhere else in technology because software is so complicated. Beauty is the ultimate defense against complexity. D. Gelernter Small minds are concerned with the extraordinary, great minds with the ordinary. Blaise Pascal Sometimes it is the people no one can imagine anything of who do the things no one can imagine. Alan Turing It can be better to copy a little code than to pull in a big library for one function. Dependency hygiene trumps code reuse. Rob Pike I think you should always bear in mind that entropy is not on your side. Elon Musk Computer Science education cannot make anybody an expert programmer any more than studying brushes and pigment can make somebody an expert painter. E. Raymond Beware of programmers who carry screwdrivers. Leonard Brandwein Getting information off the Internet is like taking a drink from a fire hydrant Mitch Kapor Don't get suckered in by the comments, they can be terribly misleading: Debug only the code. Dave Storer Code Smell 75 - Comments Inside a Method C++ is designed to allow you to express ideas, but if you don't have ideas or don't have any clue about how to express them, C++ doesn't offer much help. Bjarne Stroustrup Code Smell 56 - Preprocessors Less than 10% of the code has to do with the ostensible purpose of the system; the rest deals with input-output, data validation, data structure maintenance, and other housekeeping. Mary Shaw Programs, like people, get old. We can’t prevent aging, but we can understand its causes, limit its effects and reverse some of the damage. Mario Fusco The best performance improvement is the transition from the nonworking state to the working state. J. Osterhout People tend to overestimate what can be done in one year and to underestimate what can be done in five or ten years. Joseph Licklider Don't be (too) clever. My point was to discourage overly clever code because "clever code" is hard to write, easy to get wrong, harder to maintain, and often no faster than simpler alternatives because it can be hard to optimize. Bjarne Stroustrup Optimization hinders evolution. Everything should be built top-down, except the first time. Simplicity does not precede complexity, but follows it. Alan Perlis Computer science inverts the normal. In normal science, you're given a world, and your job is to find out the rules. In computer science, you give the computer the rules, and it creates the world. Alan Kay The good news is: Anything is possible on your computer. The bad news is: Nothing is easy. Ted Nelson Bugs lurk in corners and congregate at boundaries. Boris Beizer Take reasonable steps to test, document, and otherwise draw attention to the assumptions made in every module and routine. Daniel Read Simple systems are not feasible because they require infinite testing. Norman Ralph Augustine I’m not a great programmer; I’m just a good programmer with great habits. Kent Beck Conceptual integrity is the most important consideration in system design. Frederick P. Brooks The workers and professionals of the world will soon be divided into two distinct groups. Those who will control computers and those who will be controlled by computers. It would be best for you to be in the former group. Lewis D. Eigen Inside every well-written large program is a well-written small program. C.A.R. Hoare Code Smell 98 - Speling Mistakes I can’t be as confident about computer science as I can about biology. Biology easily has 500 years of exciting problems to work on. It’s at that level. Donald Knuth We must not forget that the wheel is reinvented so often because it is a very good idea; I've learned to worry more about the soundness of ideas that were invented only once. David L. Parnas A data structure is just a stupid programming language. Bill Gosper Code Smell 55 - Object Orgy The Analytical Engine has no pretensions whatever to originate anything. It can do whatever we know how to order it to perform… But it is likely to exert an indirect and reciprocal influence on science itself. Ada Lovelace Every craftsman starts his or her journey with a basic set of good-quality tools. Andrew Hunt Don't worry about design, if you listen to your code a good design will appear...Listen to the technical people. If they are complaining about the difficulty of making changes, then take such complaints seriously and give them time to fix things. Martin Fowler The programmer's primary weapon in the never-ending battle against slow system is to change the intramodular structure. Our first response should be to reorganize the modules' data structures. Frederick P. Brooks Code Smell 92 - Isolated Subclasses Names Luck is the residue of design. Wesley Branch Rickey The most dangerous kind of waste is the waste we do not recognize. Shigeo Shingo Start out with finding the right problem to solve. This is a combination of “what customers are asking for”, “what customers don’t even know they want yet” and “what can be solved with something simple to understand and manage”. Radia Perlman It is far easier to design a class to be thread-safe than to retrofit it for thread safety later. Brian Goetz Code Smell 112 - Testing Private Methods Defect-free software does not exist. Wietse Venema If you want to do interesting software, you have to have a bunch of people do it, because the amount of software that one person can do isn't that interesting. Nathan Myhrvold Just because something is easy to measure doesn't mean it's important. David Heinemeier Hansson That which optimizes one part of the system necessarily undermines the system as a whole. Eric Ries Physics is the universe’s operating system. Steven R Garman Good programming is good writing. John Shore Temporary solutions often become permanent problems. Craig Bruce If we wish to count lines of code, we should not regard them as "lines produced" but as "lines spent". Edsger Dijkstra Behavior is the most important thing about software. It is what users depend on. Users like it when we add behavior (provided it is what they really wanted), but if we change or remove behavior they depend on (introduce bugs), they stop trusting us. Michael Feathers Adapting old programs to fit new machines usually means adapting new machines to behave like old ones. Alan J. Perlis If you can't explain it simply, you don't understand it well enough. Albert Einstein Good engineering is the difference between code running in eight minutes or eight hours. It affects real people in real ways. It's not a "matter of opinion." any more than a bird taking a flight is a "matter of opinion." H. W. Kenton The whole of arithmetic now appeared within the grasp of mechanism. Charles Babbage Technology is dominated by two types of people: those who understand what they do not manage, and those who manage what they do not understand. Archibald Putt I know testers who make good devs. I know devs who make good testers. I know Scrum Masters who make good coffee. David Evans Code should be remarkably expressive to avoid most of the comments. There'll be a few exceptions, but we should see comments as an 'failure of expression' until proven wrong. Robert Martin Don’t document the problem, fix it. Atli Björgvin Oddsson One of the best programming skills you can have is knowing when to walk away for awhile. Oscar Godson The fundamental problem with program maintenance is that fixing a defect has a substantial chance of introducing another. Fred Brooks I think the lack of reusability comes in object-oriented languages, not in functional languages. Because the problem with object-oriented languages is they've got all this implicit environment that they carry around with them. You wanted a banana but what you got was a gorilla holding the banana and the entire jungle. Joe Armstrong Almost without exception, the best products are developed by teams with desire to solve a problem; not a company's need to fulfil a strategy. Jeff Weiner Science is a way of thinking much more than it is a body of knowledge. Carl Sagan The flip side of the coin was that even good programmers and language designers tended to do terrible extensions when they were in the heat of programming, because design is something that is best done slowly and carefully. Alan Kay An error doesn't become a mistake until you refuse to correct it. Orlando Aloysius Battista Complexity is a sign of technical immaturity. Simplicity of use is the real sign of a well design product whether it is an ATM or a Patriot missile. Daniel T. Ling Code Smell 106 - Production Dependent Code In a software project team of 10, there are probably 3 people who produce enough defects to make them net negative producers. Gordon Schulmeyer Simplicity before generality, use before reuse. Kevlin Henney Code Smell 107 - Variables Reuse You start digging in the code. The more you dig, the more stuff you turn up. Eventually you dig yourself into a hole you can’t get out of. To avoid digging your own grave, refactoring must be done systematically. Eric Gamma We live in a world of misconceptions of thinking knowing syntax is at the heart of the problems. A lot of people believe there's a technical solution to every problem and that it would be best for all us to sit in dark rooms working quietly by ourselves. GeePaw Hill GeePaw Hill - Want More Value Faster Take Many More Much Smaller Steps Do not use humans for jobs computers can do better - this is a waste of human energy and creativity, the only real resource on this planet, and demeans the human spirit. J. Paul Morrison Objects are abstractions of processing. Threads are abstractions of schedule. James O. Coplien We know about as much about software quality problems as they knew about the Black Plague in the 1600s. We've seen the victims' agonies and helped burn the corpses. We don't know what causes it; we don't really know if there is only one disease. We just suffer -- and keep pouring our sewage into our water supply. Tom Van Vleck Temporary variables can be a problem. They are only useful within their own routine, and therefore they encourage long, complex routines. Martin Fowler I think test-driven design is great. But you can test all you want and if you don’t know how to approach the problem, you’re not going to get a solution. Peter Norvig Code generation, like drinking alcohol, is good in moderation. Alex Lowe 08 - Lazyness II - Code Wizards No amount of testing can prove a software right, a single test can prove a software wrong. Amir Ghahrai As someone who was basically a software engineer for many years, I became fascinated with how the brain functions and is put together and works in such a different fashion than computers do. Paul Allen The art of debugging is figuring out what you really told your program to do rather than what you thought you told it to do. Andrew Singer Forget this world and all its troubles and if possible its multitudinous Charlatans - everything in short but the Enchantress of Numbers. Ada Lovelace While it is a known fact that programmers never make mistakes, it is still a good idea to humor the users by checking for errors at critical points in your program. Robert D. Schneider Code Smell 97 - Error Messages Without Empathy Absence of evidence is not evidence of absence. Carl Sagan The best error message is the one that never shows up. Thomas Fuchs There have been people that suggest that we should have a back door. But the reality is if you put a back door in, that back door's for everybody - for good guys and bad guys. Tim Cook The designer of a new system must not only be the implementor and the first large-scale user; the designer should also write the first user manual. If I had not participated fully in all these activities, literally hundreds of improvements would never have been made. Donald Knuth First, solve the problem. Then, write the code. John Johnson Be careful to preserve the orthogonality of your system as you introduce third-party toolkits and libraries. Choose your technologies wisely. Andy Hunt It’s better to wait for a productive programmer to become available than it is to wait for the first available programmer to become productive. Steve McConnell A programming language is a system of notation for describing computations. A useful programming language must therefore be suited for both description (i.e., for human writers and readers of programs) and for computation (i.e., for efficient implementation on computers). But human beings and computers are so different that it is difficult to find notational devices that are well suited to the capabilities of both. R. Tennant The main activity of programming is not the origination of new independent programs, but in the integration, modification, and explanation of existing ones. Terry Winograd All models are wrong but some models are useful George Box BASIC is to computer programming as QWERTY is to typing. Seymour Papert Before you say you can’t do something, try it. Sakichi Toyoda Anytime you put a challenge out there, people come up with a creative solution on the software side. Henry Samueli Simplify, don’t complicate – especially processes, procedures and policies. Richard A. Moran When in doubt, leave it out. Joshua Bloch Architecture is the tension between coupling and cohesion. Neal Ford Code Smell 16 - Ripple Effect JavaScript is the only language that I'm aware of that people feel they don't need to learn before they start using it. Douglas Crockford This ‘users are idiots, and are confused by functionality’ mentality of Gnome is a disease. If you think your users are idiots, only idiots will use it. Linus Torvalds Code Smell 105 - Comedian Methods The role of a trainer or consultant is to empower the customer, not to make himself indispensable. Bertrand Meyer Writing software is a very intense, very personal thing. You have to have time to work your way through it, to understand it. Then debug it. Vint Cerf If you automate a mess, you get an automated mess. Rod Michael That's the thing about people who think they hate computers. What they really hate is lousy programmers. Larry Niven When solving problems, dig at the roots instead of just hacking at the leaves. Anthony J. D'Angelo Syntactic sugar causes cancer of the semicolon. Alan J. Perlis The best programmers write only easy programs. Michael A. Jackson There is only one thing more painful than learning from experience, and that is not learning from experience. Archibald McLeish A computer lets you make more mistakes faster than any other invention with the possible exceptions of handguns and Tequila. Mitch Ratcliffe Fail Fast Many people tend to look at programming styles and languages like religions: if you belong to one, you cannot belong to others. But this analogy is another fallacy. Niklaus Wirth Promoting a good developer to management is often a twofold bad move: you'll lose a good developer and get a poor manager. Mario Fusco The sooner you start to code, the longer the program will take. Roy Carlson In a room full of top software designers, if two agree on the same thing, that's a majority. Bill Curtis He who hasn't hacked assembly language as a youth has no heart. He who does as an adult has no brain. John Moore Computer science is like engineering; it is all about getting something to do something, rather than just dealing with abstractions, as in the pre-Smith geology. Richard Feynman Quality is the ally of schedule and cost, not their adversary. If we have to sacrifice quality to meet schedule, it's because we are doing the job wrong from the very beginning. James A. Ward The best reaction to “this is confusing, where are the docs” is to rewrite the feature to make it less confusing, not write more docs. Jeff Atwood There is no single development, in either technology or management technique, which by itself promises even one order-of-magnitude improvement within a decade in productivity, in reliability, in simplicity. Frederick P. Brooks The most important property of a program is whether it accomplishes the intention of its user. C.A.R Hoare Tests are the Programmer’s stone, transmuting fear into boredom. Kent Beck Rules of Optimization: Rule 1: Don't do it. Rule 2 (for experts only): Don't do it yet. Michael A. Jackson Language designers are not intellectuals. They're not as interested in thinking as you might hope. They just want to get a language done and start using it. Dave Moon Writing in C or C++ is like running a chain saw with all the safety guards removed. Bob Gray Most of you are familiar with the virtues of a programmer. There are three, of course: laziness, impatience, and hubris. Larry Wall A good threat is worth a thousand tests. Boris Beizer The world is changing, and I believe that, if I want to stay employed as a programmer, I'm going to have to change with it. Kent Beck Program construction consists of a sequence of refinement steps. Niklaus Wirth Most xml i’ve seen makes me think i’m dyslexic. it also looks constipated, and two health problems in one standard is just too much. Charles Forsyth A program that produces incorrect results twice as fast is infinitely slower. John Osterhout Code Smell 76 - Generic Assertions Programming is just saying “I have a meeting in an hour, so better not start on this yet” to yourself until you die. Alex Engelberg Technology is anything invented after you were born. Alan Kay Most of the effort in the software business goes into the maintenance of code that already exists. Wietse Venema Criticism isn't just disliking things. Arts schools teach the skill & the respect for the work. Computer science schools don't. Kent Beck Whenever possible, steal code. Tom Duff The problem with using C++... is that there's already a strong tendency in the language to require you to know everything before you can do anything. Larry Wall God could create the world in six days because he didn't have to make it compatible with the previous version. Mark Twain The danger of standard process is that people will miss chances to take important shortcuts. T. DeMarco and T. Lister Controlling complexity is the essence of computer programming. Brian W. Kernighan The strength of JavaScript is that you can do anything. The weakness is that you will. Reg Braithwaite Defects are not free. Somebody makes them, and gets paid for making them. W Deming By relieving the brain of all unnecessary work, a good notation sets it free to concentrate on more advanced problems, and in effect increases the mental power of the race. Before the introduction of the Arabic notation, multiplication was difficult, and division even of integers called into play the highest mathematical faculties. Our modern power of easy reckoning with decimal fractions is the almost miraculous result of the gradual discovery of a perfect notation. Alfred North Whitehead Programmers regard themselves as artists. As such they consider keeping accurate records of their handwork on par with washing ashtray. Otis Port The heart of software is its ability to solve domain-related problems for its user. All other features, vital though they may be, support this basic purpose. Eric Evans Incorrect documentation is often worse than no documentation. Bertrand Meyer Referential transparency is a very desirable property: it implies that functions consistently yield the same results given the same input, irrespective of where and when they are invoked. Edward Garson Code Smell 93 - Send me Anything If debugging is the process of removing software bugs, then programming must be the process of putting them in. Edsger Dijkstra Code Smell 36 - Switch case elseif else if statements We must not blame programmers for their bugs. They belong to them only until the code is merged to the repository. After that, all bugs are ours! Yegor Bugayenko It is easier to change the specification to fit the program than vice versa. Alan Perlis Documentation is the castor oil of programming Gerald M. Weinberg What would happen if you allowed a bug to slip through a module, and it cost your company $10,000? The nonprofessional would shrug his shoulders, say “stuff happens,” and start writing the next module. The professional would write the company a check for $10,000! Bob Martin Any man can make mistakes, but only an idiot persists in his error. Marcus Cicero One difference between a smart programmer and a professional programmer is that the professional understands that clarity is king. Professionals use their powers for good and write code that others can understand. Robert C. Martin Code Smell 79 - TheResult Programming is not a zero-sum game. Teaching something to a fellow programmer doesn’t take it away from you. John Carmack More good code has been written in languages denounced as “bad” than in languages proclaimed “wonderful” — much more. Bjarne Stroustrup There are two ways of constructing a software design. One way is to make it so simple that there are obviously no deficiencies. And the other way is to make it so complicated that there are no obvious deficiencies. C. A. R. Hoare The computers do what you tell them to do, not what you want them to do. Alexander Atanasov If you have too many special cases, you are doing it wrong. Craig Zerouni If you think you are worth what you know, you are very wrong. Your knowledge today does not have much value beyond a couple of years. Your value is what you can learn and how easily you can adapt to the changes this profession brings so often. Jose M. Aguilar Innovation distinguishes between a leader and a follower. Steve Jobs A programming language is for thinking about programs, not for expressing programs you've already thought of. It should be a pencil, not a pen. Paul Graham If programmers got paid to remove code from software instead of writing new code, software would be a whole lot better. Nicholas Negroponte The most disastrous thing that you can ever learn is your first programming language. Alan Kay The problem is, in software design, often the consequences of your decisions don't become apparent for years. Kent Beck Each pattern describes a problem which occurs over and over again in our environment, and then describes the core of the solution to that problem, in such a way that you can use this solution a million times over, without ever doing it the same way twice. Christopher Alexander If you're actually doing TDD, you're throwing away tests all the time, as your understanding of what the code is changes. Kerri Miller One of the best things to come out of the home computer revolution could be the general and widespread understanding of how severely limited logic really is. Frank Herbert I think my software is going to become so ubiquitous, so essential, that if it stops working, there will be riots. Michael J. Saylor Simplicity does not precede complexity, but follows it Alan Perlis In essence, engineering is doing what you want with what you have. J. Carmack I hired finishers because I’m a good starter and a poor finisher. Alan Kay A program is never less than 90% complete, and never more than 95% complete. Terry Baker The definition I use for a pattern is an idea that has been useful in one practical context and will probably be useful in others. Martin Fowler With good program architecture debugging is a breeze, because bugs will be where they should be. David May If you are choosing a JavaScript library purely based on popularity, I think you deserve what you get. Tom Dale A programmable mind embraces mental agility, to practice “de-learning” and “relearning” all the time. Pearl Zhu Don't wait until you have a bug to step through your code. Steve Maguire The most disastrous thing that you can ever learn is your first programming language. Alan Kay Today, most software exists, not to solve a problem, but to interface with other software. I Angell On almost anything someone does in the computer business, you can go back in the literature and prove someone had done it earlier. Ken Olsen Computers are good at following instructions, but not at reading your mind. Donald Knuth Code Smell 87 - Inconsistent Parameters Sorting I'm not saying we purposely introduced bugs or anything, but this is kind of a natural result of any complexities of software... that you can't fully test it. Will Wright The wonderful thing about dynamic typing is it lets you express anything that is computable. And type systems don’t. Once you have a type system, you don’t even know what interesting programs are there. Gilad Bracha A bad system will beat a good person every time. Edwards Deming Most of the biggest problems in software are problems of misconception. Rich Hickey The problem with driving development with small scale tests (I call them “unit tests”, but they don’t match the accepted definition of unit tests very well) is that you run the risk of implementing what you think a user wants, but having it turn out to be not what they wanted at all. Kent Beck Don't Gather Requirements, Dig for Them Andrew Hunt There is the desire of a consumer society to have no learning curves. This tends to result in very dumbed-down products that are easy to get started on, but are generally worthless and/or debilitating. Alan Kay Computer science is a restless infant and its progress depends as much on shifts in point of view as on the orderly development of our current concepts. Alan Perlis Companies should make their own enterprise systems as often as network security companies should manufacture their own aspirin. Phil Simon Write shy code — modules that don't reveal anything unnecessary to other modules and that don't rely on other modules' implementations. Dave Thomas Programming is usually taught by examples. Niklaus Wirth A complex system that works is invariably found to have evolved from a simple system that worked. John Gall Sun Microsystems had the right people to make Java into a first-class language, and I believe it was the Sun marketing people who rushed the thing out before it should have gotten out. Alan Kay A well installed microcode bug will be almost impossible to detect. Ken Thompson Playfully doing something difficult, whether useful or not, that is hacking. Richard M. Stallman There are only two kinds of languages: the ones people complain about and the ones nobody uses. Bjarne Stroustrup The cost of adding a feature isn’t just the time it takes to code it. The cost also includes the addition of an obstacle to future expansion. The trick is to pick the features that don’t fight each other. John Carmack Code Smell 110 - Switches With Defaults Science is what we understand well enough to explain to a computer, Art is all the rest Donald Knuth Programming without an overall architecture or design in mind is like exploring a cave with only a flashlight: You don't know where you've been, you don't know where you're going, and you don't know quite where you are. Danny Thorpe For us, the real goal is to make it so that the software ecosystem is as healthy as possible. James Gosling When you actually sit down to write some code, you learn things that you didn’t get from thinking about them in modeling terms…there is a feedback process there that you can only really get at from executing some things and seeing what works. Martin Fowler The problem with quick and dirty, is that the dirty remains long after the quick has been forgotten Steve C. McConnell If you put fences around people, you get sheep. GIve people the room they need. William L. McKnight Whether you draw diagrams that generate code or you type at a browser, you are coding. Kent Beck If you make a general statement, a programmer says, 'Yes, but...' while a designer says, 'Yes, and...' André Bensoussan Blame the implementation, not the technique. Tim Kadlec Get out of the way of your developers or lose them to someone who will. Adrian Cockcroft Memory is like an orgasm. It's a lot better if you don't have to fake it. Seymour Cray The most important single aspect of software development is to be clear about what you are trying to build. Bjarne Stroustrup If you're a technical lead, you need to be coding. Martin Fowler Einstein repeatedly argued that there must be simplified explanations of nature, because God is not capricious or arbitrary. No such faith comforts the software engineer. Fred Brooks No Silver Bullet Quality is never an accident; it is always the result of intelligent effort. John Ruskin Software eventually and necessarily gained the same respect as any other discipline. Margaret H. Hamilton If it takes more than a sentence to explain what you are doing, it’s almost always a sign that what you are doing is too complicated. Sam Altman Code Smell 85 - And Functions One of the things I've been trying to do is look for simpler or rules underpinning good or bad design. I think one of the most valuable rules is avoiding duplication. "Once and only once" is the Extreme Programming phrase. Martin Fowler Subclasses shouldn’t always share all characteristics of their parent class but will do so with inheritance. This can make a program’s design less flexible. It also introduces the possibility of calling methods on subclasses that don’t make sense or that cause errors because the methods don’t apply to the subclass. Steve Klabnik Code Smell 37 - Protected Attributes The greatest obstacle to discovery is not ignorance, but the illusion of knowledge. Daniel Boorstin The most disastrous thing that you can ever learn is your first programming language. Alan Kay In 2031, lawyers will be commonly a part of most development teams. Grady Booch Everything will ultimately fail. Hardware is fallible, so we add redundancy. This allows us to survive individuals hardware failures, but increases the likelihood of having at least one failure at any given time. Michael Nygard Programmers are as emotional and irrational as normal people. Douglas Crockford There is nothing so useless as doing efficiently that which should not be done at all. Peter Drucker It is easier to write an incorrect program than understand a correct one Alan J. Perlis It's easy to cry "bug" when the truth is that you've got a complex system and sometimes it takes a while to get all the components to co-exist peacefully. D. Vargas A language that doesn’t affect the way you think about programming, is not worth knowing. Alan Perlis You can mass-produce hardware; you cannot mass-produce software; you cannot mass-produce the human mind. Michio Kaku Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization’s communication structure. Melvin Conway Optimism is an occupational hazard of programming: feedback is the treatment. Kent Beck Good programmers use their brains, but good guidelines save us having to think out every case. Francis Glassborow Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live. John Woods Code Smell 91 - Test Asserts without Description Successful software always gets changed. Fred Brooks If we want users to like our software, we should design it to behave like a likeable person. Alan Cooper The lesson is: Even if you know exactly what is going on in your system, measure performance, don't speculate. You'll learn something, and nine times out of ten, it won't be that you were right! Ron Jeffries 07 - Benefits Of Going Beyond The Make-It-Work Phase - Francisco Climent God made the natural numbers; all else is the work of man. Leopold Kronecker Code Smell 108 - Float Assertions Languages that try to disallow idiocy become themselves idiotic. Rob Pike A heuristic we follow is that whenever we feel the need to comment something, we write a method instead. Martin Fowler We are still in the infancy of naming what is really happening on software development projects. Alistair Cockburn Thinking about my experience of modifying code, I see that I spend much more time reading the existing code than I do writing new code. If I want to make my code cheap, therefore, I should make it easy to read. Kent Beck Code Smell 96 - My Objects In software design, it's all about making a guess, trying it, and then learning from the experience. Stewart Butterfield Static typing is to reliable programming what a spelling checker is to a good writer. Peter Van Roy If you have a procedure with ten parameters, you probably missed some. Alan Perlis Redundant comments are just places to collect lies and misinformation. Robert Martin My belief is still, if you get the data structures and their invariants right, most of the code will kind of write itself. Peter Deustch When you are stuck in a traffic jam with a Porsche, all you do is burn more gas in idle. Scalability is about building wider roads, not about building faster cars. Steve Swartz Watch the little things; a small leak will sink a great ship. Benjamin Franklin Good code is its own best documentation. Steve McConnell If you have to spend effort looking at a fragment of code and figuring out what it’s doing, then you should extract it into a function and name the function after the what. Martin Fowler Code Smell 05 - Comment Abusers Remember, code is your house, and you have to live in it. Michael C. Feathers No one hates software more than software developers. Jeff Atwood Skilled and motivated programmers can overcome inadequate processes, but perfect processes can never compensate for inadequate programmers or poor software managers. Dick Fairley A good enough first version will take longer to produce with $170K than it would have with $0K. Jason Fried I'm a victim of Developaralysis: the crippling sense that the software industry is evolving so fast that no one person can possibly keep up. Jon Evans Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it. Alan Perlis Code Smell 94 - Too Many imports No matter how slow you are writing clean code, you will always be slower if you make a mess. Robert Martin Code Smell 64 - Inappropriate Intimacy The nice thing about standards is that there are so many to choose from. Andrew S. Tannenbaum Code Smell 48 - Code Without Standards Playing with pointers is like playing with fire. Fire is perhaps the most important tool known to man. Carefully used, fire brings enormous benefits; but when fire gets out of control, disaster strikes. J Barnes The objective of cleaning is not just to clean, but to feel happiness living within that environment. Marie Kondo When I write software, I know that it will fail, either due to my own mistake, or due to some other cause. Wietse Venema It’s harder to read code than to write it. Joel Spolsky Code Smell 51 - Double Negatives Complexity kills. It sucks the life out of developers, it makes products difficult to plan, build and test, it introduces security challenges, and it causes end-user and administrator frustration. Ray Ozzie Clearly, programming courses should teach methods of design and construction, and the selected examples should be such that a gradual development can be nicely demonstrated. Niklaus Wirth Twenty percent of all input forms filled out by people contain bad data. Dennis Ritchie Code Smell 113 - Data Naming That's why I write, because life never works except in retrospect. You can't control life, at least you can control your version. Chuck Palahniuk Code Smell 57 - Versioned Functions If you get tired of writing for loops, take a break and continue later. David Walker Code Smell 53 - Explicit Iteration The most beautiful code, the most beautiful functions, and the most beautiful programs are sometimes not there at all. Jon Bentley Code Smell 77 - Timestamps The proper use of comments is to compensate for our failure to express ourselves in code. Robert C. Martin It is not the language that makes programs appear simple. It is the programmer that make the language appear simple. Robert Martin Scientists build to learn; Engineers learn to build. Fred Brooks Don't Live with Broken Windows Andy Hunt Programmers don't burn out on hard work, they burn out on change-with-the-wind directives and not 'shipping'. Mark Berry We have to stop optimizing for programmers and start optimizing for users. Jeff Atwood Code Smell 88 - Lazy Initialization It is hard to write even the smallest piece of code correctly. Joshua Bloch The optimum committee has no members. Norman Ralph Augustine I do not fear computers. I fear lack of them. Isaac Asimov An organization that treats its programmers as morons will soon have programmers that are willing and able to act like morons only. Bjarne Stroustrup If you have three pet dogs, give them names. If you have 10,000 head of cattle, don't bother. Nowadays, the idea of giving a name to every file on your computer is ridiculous. David Gelernter Code Smell 45 - Not Polymorphic The computer programmer is a creator of universes for which he alone is the lawgiver. No playwright, no stage director, no emperor, however powerful, has exercised such absolute authority to arrange a stage or field of battle. Joseph Weizenbaum Design patterns should not be applied indiscriminately. Often they achieve flexibility and variability by introducing additional levels of indirection. A design pattern should only be applied when the flexibility it affords is actually needed. Erich Gamma Agile methods derive much of their agility by relying on the tacit knowledge embodied in the team, rather than writing the knowledge down in plans. Barry Boehm A program which perfectly meets a lousy specification is a lousy program. Cem Kaner Error handling is important, but if it obscures logic, it’s wrong. Robert Martin Code Smell 72 - Return Codes When debugging, novices insert corrective code; experts remove defective code. Richard Pattis Code Smell 73 - Exceptions for Expected Cases A good programmer is someone who always looks both ways before crossing a one-way street. Doug Linder Alzheimer's Law of Programming: Looking at code you wrote more than two weeks ago is like looking at code you are seeing for the first time. Dan Hurvitz The cleaner and nicer the program, the faster it's going to run. And if it doesn't, it'll be easy to make it fast. Joshua Bloch Writing software as if we are the only person that ever has to comprehend it is one of the biggest mistakes and false assumptions that can be made. Karolina Szczur Code Smell 80 - Nested Try Catch Standards are always out of date. That’s what makes them standards. Alan Bennett The best smells are something that's easy to spot and most of time lead you to really interesting problems. Data classes (classes with all data and no behavior) are good examples of this. You look at them and ask yourself what behavior should be in this class. Martin Fowler The most unsuccessful three years in the education of cost estimators appears to be fifth-grade arithmetic. Norman R. Augustine Complexity has nothing to do with intelligence, simplicity does. Larry Bossidy If the code and the comments disagree, then both are probably wrong. Norm Schryer Those who can imagine anything, can create the impossible Alan Turing I think it is inevitable that people program poorly. Training will not substantially help matters. We have to learn to live with it. Alan Perlis My computer's so fast it finishes an infinite loop in 5 minutes. Chisel Wright I object to doing things that computers can do. Olin Shivers The amateur software engineer is always in search of magic. Grady Booch Code Smell 52 - Fragile Tests Truth can only be found in one place: the code. Robert C. Martin The benefits of a truly effective new technology are foregone when, in the rush to try out the next shiny whiz-bang tool, we abandon the current one. Scott Guthrie A language that doesn’t have everything is actually easier to program in than some that do." ~ Dennis M. Ritchie It's not at all important to get it right the first time. It's vitally important to get it right the last time. Andrew Hunt and David Thomas Prolific developers don’t always write a lot of code, instead they solve a lot of problems. The two things are not the same. J. Chambers Programs are meant to be read by humans and only incidentally for computers to execute. Donald Knuth A programming language is low level when its programs require attention to the irrelevant. Alan J. Perlis This will surprise some of your readers, but my primary interest is not with computer security. I am primarily interested in writing software that works as intended. Wietse Venema You will fall to ruin because you believe that exceptions to the rule make new rules. Pierce Brown Code Smell 26 - Exceptions Polluting Every time you write a comment, you should grimace and feel the failure of your ability of expression Robert Martin Simplicity is the soul of efficiency. Austin Freeman Code Smell 29 - Settings - Configs Inheritance is surely a good answer but who knows the questions? Michel Gauthier Programming can be fun, so can cryptography; however they should not be combined. Kreitzberg & Shneiderman Code Smell 06 - Too Clever Programmer So much complexity in software comes from trying to make one thing do two things. Ryan Singer Code Smell 34 - Too Many Attributes Deleted code is debugged code. Jeff Sickel Any fool can write code that a computer can understand. Good programmers write code that humans can understand. Martin Fowler The ratio of time spent reading (code) versus writing is well over 10 to 1 ... (therefore) making it easy to read makes it easier to write. Robert Martin Just as it is a good practice to make all fields private unless they need greater visibility, it is a good practice to make all fields final unless they need to be mutable. Brian Goetz Rather than apply minutes of suspect reasoning, we can just ask the computer by making the change and running the tests. Kent Beck Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away. Antoine de Saint Exupéry Any code of your own that you haven’t looked at for six or more months might as well have been written by someone else. Eagleson’s Law Automated testing is a safety net that protects the program from its programmers. Yegor Bugayenko One day my daughter came in, looked over my shoulder at some Perl 4 code, and said, "What is that, swearing?" Larry Wall It´s more about good enough than it is about right or wrong. James Bach The methodologies and best practices used to develop software can be applied successfully to any challenge in life. Walter O'Brien No one in the brief history of computing has ever written a piece of perfect software. It's unlikely that you'll be the first. Andy Hunt Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it. Brian Kernighan If you say “I told you so”, you are the one who has failed. Because you knew, but did not manage to stop the train wreck. Robert Martin Some people, when confronted with a problem, think “I know, I’ll use regular expressions.” Now they have two problems. Jamie Zawinski The best way to get accurate information on Stack Overflow is to post something wrong and wait for corrections. Matthew Austern Don’t comment bad code — rewrite it. Brian Kernighan 15 - What exactly is a name — Part II Rehab Code is like humor. When you have to explain it, it’s bad. Cory House Code Smell 81 - Result A long descriptive name is better than a short enigmatic name. A long descriptive name is better than a long descriptive comment. Robert Martin Code Smell 33 - Abbreviations Talk is cheap. Show me the code. Linus Torvalds The language in which we express our ideas has a strong influence on our thought processes. Don Knuth Smart data structures and dumb code works a lot better than the other way around. Eric Raymond Legacy code is code without tests. Michael Feathers 13 - How to Decouple a Legacy System Regardless of your plans, production is the ultimate testing environment. J T Wall Somebody will say they have a program that’s verified and it’s only verified because it met its specification according to some verifier. But the verifier might have bugs in it. The specifications might have bugs in them Donald Knuth The first 90 percent of the code accounts for the first 90 percent of the development time. The remaining 10 percent of the code accounts for the other 90 percent of the development time Tom Cargill One man's crappy software is another man's full time job. Jessica Gaston Code Smell 42 - Warnings Strict Mode Off We're entering a new world in which data may be more important than software. Tim O'Reilly The pesticide paradox. Every method you use to prevent or find bugs leaves a residue of subtler bugs against which those methods are ineffective. Boris Beizer Code Smell 30 - Mocking Business I try to think mostly in terms of preconditions, and checking things in the constructor and the beginning of a function. Brad Fitzpatrick "Don't fix it if it ain't broke" presupposed that you can't improve something that works reasonably well already. If the world's inventors had believed this, we'd still be driving Model A Fords and using outhouses. H. W. Kenton Good software, like wine, takes time. Joel Spolsky Pasting code from the internet into production code is like chewing gum found in the street. Mike Johnson Discovering the unexpected is more important than confirming the known. George E. P. Box Pay attention to zeros. If there is a zero, someone will divide by it. Cem Kaner Beta testing is a symptom of weak testing practices and poor communication with customers Kent Beck Beware of bugs in the above code; I have only proved it correct, not tried it. Donald Knuth 29 - Stop Calling them ‘Bugs’ The key to building a great product is building a great team first. To me, great teams aren’t bound by roles, but they’re driven by moving forward. Alan Page Simplicity, carried to the extreme, becomes elegance. Jon Franklin With tests, we can change the behavior of our code quickly and verifiably. Without them, we really don’t know if our code is getting better or worse.” Michael Feathers 20 - How to Squeeze Test Driven Development on Legacy Systems Don't patch bad code - rewrite it. P. J. Plauger Correctness is clearly the prime quality. If a system does not do what it is supposed to do, then everything else about it matters little. Bertrand Meyer Code Smell 86 - Mutable Const Arrays A Perl program is correct if it gets the job done before your boss fires you. Larry Wall Code Smell 41 - Regular Expression Abusers As the Tests get more Specific, the Code gets more Generic. Robert Martin Software testing is not only ensuring absence of bugs but also ensuring presence of value. Amit Kalantri Quality is free, but only to those who are willing to pay heavily for it. DeMarco and Lister Developer testing is an important step towards accountability. It gives developers a way to demonstrate the quality of the software they produce. Kent Beck It’s hard enough to find an error in your code when you’re looking for it; its even harder when you’ve assumed your code is error-free. Steve McConnell On the seventh day, God said, "Ship it! We'll release patches later." Josh Flachsbart Make it hard to ignore error conditions. Don't bury error codes in return values. Steve Maguire One of the most valuable things about TDD is that it lets us concentrate on one thing at a time. We are either writing code or refactoring; we are never doing both at once. Michael Feathers You haven't mastered a tool until you understand when it should not be used. Kelsey Hightower Reducing a product's definition to a list of features and functions ignores the real opportunity - orchestrating technological capability to serve human needs and goals. Alan Cooper Beyond basic mathematical aptitude, the difference between good programmers and great programmers is verbal ability. Marissa Mayer Code Smell 90 - Implementative Callback Events We argue that design practices which take a data-driven approach fail to maximize encapsulation because they focus too quickly on the implementation of objects. We propose an alternative object-oriented design method which takes a responsibility-driven approach. Rebecca Wirf Brooks Code Smell 63 - Feature Envy .. one of the main causes of the fall of the Roman Empire was that, lacking zero, they had no way to indicate successful termination of their C programs. Robert Firth Software never was perfect and won’t get perfect. But is that a license to create garbage? The missing ingredient is our reluctance to quantify quality. Boris Beizer Nothing makes a system more flexible than a suite of tests. Robert Martin Code Smell 82 - Tests Violating Encapsulation Programming is similar to a game of golf. The point is not getting the ball in the hole but how many strokes it takes. Harlan D. Mills If you’re afraid to change something it is clearly poorly designed. Martin Fowler As a rule, software systems do not work well until they have been used, and have failed repeatedly, in real applications. David Parnas There are two ways to write error-free programs; only the third one works. Alan J. Perlis Whenever I have to think to understand what the code is doing, I ask myself if I can refactor the code to make that understanding more immediately apparent. Martin Fowler Code Smell 67 - Middle Man A true professional does not waste the time and money of other people by handing over software that is not reasonably free of obvious bugs; that has not undergone minimal unit testing; that does not meet the specifications and requirements; that is gold-plated with unnecessary features; or that looks like junk. Daniel Read Let there be no doubt that object-oriented design is fundamentally different than traditional structured design approaches: it requires different ways of thinking about decomposition, and it produces software architectures that are largely outside the realm of the structured design culture. Grady Booch I invented the term ‘object oriented’, and C++ was not what I had in mind. Alan Kay Part of the objective of this series of articles is to generate spaces for debate and discussion on software design. Original Thread on Twitter