Software Engineering Great Quotes

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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.

Software Design

There are only two hard things in Computer Science: cache invalidation and naming things.

Phil Karlton

Make illegal states unrepresentable.

Yaron Minsky

First make the change easy (warning: this might be hard), then make the easy change.

Kent Beck

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

Science is what we understand well enough to explain to a computer. Art is everything else we do.

Donald Knuth

The biggest issue on software teams is making sure everyone understands what everyone else is doing.

Martin Fowler

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

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

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

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

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.


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

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

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

Without requirements or design, programming is the art of adding bugs to an empty text file.

Louis Srygley

A data structure is just a stupid programming language.

Bill Gosper

Good programmers never write what they can steal or borrow.

Jeff Atwood

It is very hard to predict, especially the future.

Niels Bohr

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

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

If you lie to the compiler, it will get its revenge.

Henry Spencer

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

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

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

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

Final source code is the real software design.

Jack Reeves

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

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

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

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

There’s nothing more permanent than a temporary hack.

Kyle Simpson

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

Learning to code is useful no matter what your career ambitions are.

Arianna Huffington

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

The purpose of computing is insight, not numbers.

Richard Hamming

Write shy code — modules that don't reveal anything unnecessary to other modules and that don't rely on other modules' implementations.

Dave Thomas

The trick is to fix the problem you have, rather than the problem you want.

Bram Cohen

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

Software is a gas; it expands to fill its container.

Nathan Myhrvold

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

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

Simplicity is prerequisite for reliability.

Edsger W. Dijkstra

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

Before software can be reusable it first has to be usable.

Ralph Johnson

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

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

Premature optimization is the root of all evil

Donald Knuth

When in doubt, use brute force.

Ken Thompson

Any problem in computer science can be solved with another level of indirection.

David Wheeler

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

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

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

Developers are drawn to complexity like moths to a flame, frequently with the same result.

Neal Ford

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

In programming, the hard part isn't solving problems, but deciding what problems to solve.

Paul Graham

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

Computer Science education cannot make anybody an expert programmer any more than studying brushes and pigment can make somebody an expert painter.

E. Raymond

Don't get suckered in by the comments, they can be terribly misleading: Debug only the code.

Dave Storer

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

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

I’m not a great programmer; I’m just a good programmer with great habits.

Kent Beck

Inside every well-written large program is a well-written small program.

C.A.R. Hoare

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

A data structure is just a stupid programming language.

Bill Gosper

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

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

Architecture is the tension between coupling and cohesion.

Neal Ford

The role of a trainer or consultant is to empower the customer, not to make himself indispensable.

Bertrand Meyer

A computer lets you make more mistakes faster than any other invention with the possible exceptions of handguns and Tequila.

Mitch Ratcliffe

shahadat-rahman-gnyA8vd3Otc-unsplash.jpg Photo by Shahadat Rahman on Unsplash

Programming Languages

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

He who hasn't hacked assembly language as a youth has no heart. He who does as an adult has no brain.

John Moore

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

If debugging is the process of removing software bugs, then programming must be the process of putting them in.

Edsger Dijkstra

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

In essence, engineering is doing what you want with what you have.

J. Carmack

Computers are good at following instructions, but not at reading your mind.

Donald Knuth

Write shy code — modules that don't reveal anything unnecessary to other modules and that don't rely on other modules' implementations.

Dave Thomas

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

There are only two kinds of languages: the ones people complain about and the ones nobody uses.

Bjarne Stroustrup

you-x-ventures-vbxyFxlgpjM-unsplash.jpg Photo by You X Ventures on Unsplash

Planning / Management

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

The most important single aspect of software development is to be clear about what you are trying to build.

Bjarne Stroustrup

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

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

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

The greatest obstacle to discovery is not ignorance, but the illusion of knowledge.

Daniel Boorstin

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

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

bench-accounting-nvzvOPQW0gc-unsplash.jpg Photo by Bench Accounting on Unsplash

Clean Code

Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.

John Woods

Successful software always gets changed.

Fred Brooks

A heuristic we follow is that whenever we feel the need to comment something, we write a method instead.

Martin Fowler

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

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

No matter how slow you are writing clean code, you will always be slower if you make a mess.

Robert Martin

The nice thing about standards is that there are so many to choose from.

Andrew S. Tannenbaum

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

It’s harder to read code than to write it.

Joel Spolsky

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

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

If you get tired of writing for loops, take a break and continue later.

David Walker

The most beautiful code, the most beautiful functions, and the most beautiful programs are sometimes not there at all.

Jon Bentley

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

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

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

Error handling is important, but if it obscures logic, it’s wrong.

Robert Martin

When debugging, novices insert corrective code; experts remove defective code.

Richard Pattis

A good programmer is someone who always looks both ways before crossing a one-way street.

Doug Linder

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

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

Complexity has nothing to do with intelligence, simplicity does.

Larry Bossidy

The amateur software engineer is always in search of magic.

Grady Booch

Truth can only be found in one place: the code.

Robert C. Martin

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

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

Programming can be fun, so can cryptography; however they should not be combined.

Kreitzberg & Shneiderman

So much complexity in software comes from trying to make one thing do two things.

Ryan Singer

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

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

One day my daughter came in, looked over my shoulder at some Perl 4 code, and said, "What is that, swearing?"

Larry Wall

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

Don’t comment bad code — rewrite it.

Brian Kernighan

Code is like humor. When you have to explain it, it’s bad.

Cory House

A long descriptive name is better than a short enigmatic name. A long descriptive name is better than a long descriptive comment.

Robert Martin

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


Photo by Raquel Martínez on Unsplash

Software Quality

Legacy code is code without tests.

Michael Feathers

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

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

I try to think mostly in terms of preconditions, and checking things in the constructor and the beginning of a function.

Brad Fitzpatrick

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

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

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

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

A Perl program is correct if it gets the job done before your boss fires you.

Larry Wall

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

Nothing makes a system more flexible than a suite of tests.

Robert Martin

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


Photo by Kelvyn Ornettte Sol Marte on Unsplash


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


Photo by National Cancer Institute on Unsplash

Object Oriented

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.

We look forward to comments and suggestions on this article.

Original Thread on Twitter

Comments (1)

Oliver Earl's photo

Great list! Martin, Kernighan, and Brooks were especially major inspirations that I read a lot of.

You can't beat Linus' blunt wisdom though.