Writing clean and maintainable code
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Writing code is easy but writing maintainable code is almost impossible. During this talk I will discuss some of the principles of coding that relates to WordPress but goes beyond that.
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Writing clean and maintainable code
- 1. WRITING CLEAN AND MAINTAINABLE CODE WordCamp Norway 2015
- 2. Marko Heijnen • Lead developer of GlotPress • Core contributor for WordPress • Working for 1&1 as their WordPress specialist • Fan of new technologies
- 3. Quick note This talk is not only for developers. Knowing how code should look like is important to judge it’s quality.
- 4. Bad code can bring your company down
- 5. Clean code Some parts of this presentation are from the book “Clean Code” from Robert C. Martin aka Uncle Bob
- 6. So what is clean code?
- 7. – Bjarne Stroustrup, inventor of C++ “I like my code be elegant and efficient” “Clean code does one thing well” Elegance
- 8. – Grady Booch, author of Object Oriented Analysis and Design With Applications “Clean code is simple and direct” “Clean code reads like well-written prose” Simple, direct, readable
- 9. – Dave Thomas, founder of OTI “Clean code can be read” “Clean code should be literate” Literate
- 10. – Michael Feathers, author of Working Effectively with Legacy Code “Clean code always looks like it was written by someone who cares” Care
- 11. – Ron Jeffries, author of Extreme Programming Installed “No duplication, one thing, expressiveness, tiny abstractions.” Small, expressive, simple
- 12. – Ward Cunningham, inventor of Wiki, Fit, coinventor of eXtreme Programming. Motive force behind Design Patterns “You know you are working on clean code when each routing you reads turns out to be pretty much what you expected.” What you expected
- 14. Variables, functions and methods
- 15. Meaningful names • Intention-Revealing Names • English Readability -> is_user_logged_in() • Avoid disinformation • Use pronounceable names
- 16. Meaningful names • Classes should have a noun or noun phrase names but should not be a verb • Method names should have verb or verb phrase names • Use descriptive names
- 17. The code • Should be very small! < 150 characters per line and < 20 lines • Do one thing and do that right • Limit it to one level of abstraction • Reading code from top to bottom • The ideal number of arguments for a function is zero
- 18. The code • Don’t use flag arguments • passing a boolean into a function • Pass objects as a function argument to reduce the arguments • Have no side effect, does what is expected • Don’t repeat yourself • Only return data once
- 19. What does it not mean
- 20. Having set requirements like PHP 5.4 > It happens when the functionality is required
- 21. Using namespaces Important for projects with a lot of dependencies
- 22. The use of autoloaders It could enhances startup time but it’s not the place to do so
- 23. Most of WordPress code base but every release it does get better
- 24. What does this mean for WordPress?
- 25. What does this mean for WordPress? • Follow the WordPress coding standards • A shared code base is an important aspect for clean code • Have it prefix with something that is unique
- 26. What are the violations in WordPress • A lot of global variables • Functions/Methods should never echo • Returning WP_Error instead of exceptions • WP_DB
- 27. Last but not least Test Driven Development: Unit Tests
- 28. The three laws of Test Driven Development • First law You may not write production code until you have written a failing unit test • Second law You may not write more of a unit test than is sufficient to fail, and not compiling is failing • Third law You may not write more production code than is sufficient to pass the currently failing test
- 29. Unit tests is the best documentation of your code It shows how you intended your code to be used
- 30. Keep test clean with the same standards as your production code.
- 31. Readability is key Maybe even more important then your production code
- 32. A single unit test should contain • Single concept per test • One assert per test is a good guideline • Five other rules: F.I.R.S.T • Fast • Independent • Repeatable • Self-Validating • Timely
- 33. Clean code & me
- 34. Clean code & me • I never studied Computer Science • I do care about quality and structure • I refuse to do quick wins or hacks • Work together with others to become better • Applying unit tests on existing projects • A lot of refactoring and WTF moments
- 35. WP_Image_Editor
- 36. What I have learned from working together with a Java developer
- 37. What I have learned from working together with a Java developer • Start applying all the things I discussed • Using OOP more then just wrapping functions in a class • Using a Wrapper / Decorator pattern • Think more in advance how things should work • And also think what could change
- 38. An hour discussion about hooks in WordPress
- 40. Thank you for listening Questions? @markoheijnen markoheijnen.com