108 Quotes by Robert C. Martin

"When you cannot concentrate and focus sufficiently, the code you write will be wrong. It will have bugs. It will have the wrong structure. It will be opaque and convoluted. It will not solve the customers’ real problems. In short, it will have to be reworked or redone. Working while distracted creates waste."

"It is not enough for code to work. Code that works is often badly broken. Programmers who satisfy themselves with merely working code are behaving unprofessionally. They may fear that they don’t have time to improve the structure and design of their code, but I disagree. Nothing has a more profound and long-term degrading effect upon a development project than bad code."

"Duplication is the primary enemy of a well-designed system. It represents additional work, additional risk, and additional unnecessary complexity."

"The proper use of comments is to compensate for our failure to express ourself in code. Note that I used the word failure. I meant it. Comments are always failures."

"Flag arguments are ugly. Passing a boolean into a function is a truly terrible practice."

"Another problem with service-level decoupling is that it is expensive, both in development time and in system resources. Dealing with service boundaries where none are needed is a waste of effort, memory, and cycles. And, yes, I know that the last two are cheap – but the first is not."

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

"You are reading this book for two reasons. First, you are a programmer. Second, you want to be a better programmer. Good. We need better programmers."

"Dijkstra once said, “Testing shows the presence, not the absence, of bugs.” In other words, a program can be proven incorrect by a test, but it cannot be proven correct. All that tests can do, after sufficient testing effort, is allow us to deem a program to be correct enough for our purposes."

"Every system is built from a domain-specific language designed by the programmers to describe that system. Functions are the verbs of that language, and classes are the nouns."