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lessons-learned-in-software-dev.md

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title lessons learned in software development
date 2017-11-24
captured 2017-11-24 23:39:57 UTC
tags
software-development
heuristics
debugging
teamwork
source GitHub issue #340
aliases
status refined

Context

Henrik Warne's collection of 22 heuristics and rules of thumb accumulated over years of software development, organized into four categories: development, troubleshooting, cooperation, and miscellaneous.

Source: Lessons Learned in Software Development

Development

  1. Start small, then extend. "A complex system that works is invariably found to have evolved from a simple system that worked." (John Gall)
  2. Change one thing at a time. Short iterations make it much easier to find problems. Commit refactoring separately from new features.
  3. Add logging and error handling early. Both are useful from the very beginning. As soon as something goes wrong, you need to see what is happening.
  4. All new lines must be executed at least once. Cheat if necessary: misspell a column name to trigger error handling, invert an if-statement to test rare paths.
  5. Test the parts before the whole. Well-tested parts save time when tracking down integration problems.
  6. Everything takes longer than you think. Hofstadter's Law: "It always takes longer than you expect, even when you take into account Hofstadter's Law."
  7. First understand the existing code. Reading code is as necessary a skill as writing code.
  8. Read and run. Use both methods to understand code. Running code reveals behavior that reading alone cannot.

Troubleshooting

  1. There will always be bugs. Build systems for quick troubleshooting, fixing, and deploying, not for "getting it right the first time."
  2. Solve trouble reports. Every developer should handle customer bugs. It reveals how the system is actually used.
  3. Reproduce the problem. First step always. Then verify the fix makes the problem disappear.
  4. Fix the known errors, then see what's left. Multiple bugs can interact and cause confusing symptoms.
  5. Assume no coincidences. Changed a timer and the system restarts more? Not a coincidence. Investigate.
  6. Correlate with timestamps. Look for even increments. A restart 3000ms after a request suggests a timer triggered it.

Cooperation

  1. Face to face has the highest bandwidth. Solutions are often much better after in-person discussion.
  2. Rubber ducking. Explain the problem to a colleague. You often realize the answer as you talk.
  3. Ask. If someone knowledgeable is available, ask. Minutes of conversation can replace days of code reading.
  4. Share credit. Say "Marcus came up with the idea" instead of "we tried."

Miscellaneous

  1. Try it. Write a little program to test how a language feature works. Fiddling around often reveals bugs.
  2. Sleep on it. Your subconscious works on hard problems overnight.
  3. Change. Don't be afraid to change roles or jobs. It is stimulating.
  4. Keep learning. Different languages, tools, books, courses. Small improvements compound.

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