Refactoring blockers and code smells @jNation 2021
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The document discusses the importance of refactoring in software development, highlighting techniques for code improvement without altering its external behavior. It emphasizes safe refactoring practices, overcoming challenges such as legacy code, and the benefits of incremental changes and collaboration. The content also touches on common code smells and offers strategies for efficient development habits and maintaining code quality.
Refactoring blockers and code smells @jNation 2021
- 1. VictorRentea.ro 21 victor.rentea@gmail.com ♦ ♦ @victorrentea ♦ VictorRentea.ro
- 2. Victor Rentea VictorRentea.ro Recorded Talks, Blog, Video Courses, ... Independent Trainer Founder of Bucharest Software Craftsmanship Community Java Champion ❤️ Simple Design, Refactoring, Unit Testing ❤️
- 3. Technical Training 500 days (200+ online) 2000 devs 8 years 50+ companies Reach out to me: Hibernate Spring Func Prog Java Performance Reactive Prog Design Patterns Pragmatic DDD Clean Code Refactoring Unit Testing TDD any lang @victorrentea Intense More: VictorRentea.ro Workshops: victorrentea.teachable.com
- 4. 24 CODE
- 5. 25 © VictorRentea.ro a training by Refactoring What must we do every single day? What’s that?
- 6. 26 © VictorRentea.ro a training by Simplify existing code without changing its external behavior Refactoring DO NOT BREAK PRODUCTION
- 7. 27 © VictorRentea.ro a training by
- 8. 29 © VictorRentea.ro a training by I'm afraid to refactor because we don't have tests It's impossible to test a 200-lines method! The Vicious Circle of Legacy Code Pair Programming (80% less bugs) Coding Katas! TDD Practice
- 9. 30 © VictorRentea.ro a training by Safe Refactoring Tips Next IDE Refactoring Fails Stress Don't Break Compilation (unless exploring) Automated Refactoring as much as you can Decompose Large Changes into small, safe moves Use Quick-fix to keep your focus on the design (Alt-Enter / ⌥-Enter)
- 10. 31 © VictorRentea.ro a training by Time TIME FRAME SPEED
- 11. 32 © VictorRentea.ro a training by "I don't have time. I'm too busy" Being busy is a form of laziness - Tim Ferriss Habits of Efficient Developers by Daniel Lebrero Stop! and Reflect. Focus on what matters.
- 12. 33 © VictorRentea.ro a training by Improve Your Focus Turn off desktop/mobile notifications Automate Stuff Pomodoro 25/5 No morning inbox Max 30 min meetings Digital Detox Master your IDE ➔ Get your brain to focus Chris Bailey IntelliJ Productivity Tips Victor Rentea
- 13. 35 © VictorRentea.ro a training by Time TIME FRAME SPEED
- 14. 36 © VictorRentea.ro a training by Estimates
- 15. 37 © VictorRentea.ro a training by Emotionally Involved
- 16. 38 © VictorRentea.ro a training by Ever-changing Requirements
- 17. 40 © VictorRentea.ro a training by NO
- 18. 41 © VictorRentea.ro a training by technical functional (complex requirements) iterations (the point of Agile) prototype/POC Estimations Risks
- 19. 42 © VictorRentea.ro a training by Time & Fear ☺
- 20. 43 © VictorRentea.ro a training by The Best way to understand code is to Refactor it
- 21. 44 © VictorRentea.ro a training by You lost it! You got carried away...
- 22. 45 © VictorRentea.ro a training by 3 hours later, you commit: code improvements refactoring I gotta leave Major changes
- 23. 46 © VictorRentea.ro a training by
- 24. 47 © VictorRentea.ro a training by
- 25. 48 © VictorRentea.ro a training by Explore
- 26. 49 © VictorRentea.ro a training by Exploratory Refactoring Discover Timeboxed: eg 15 min. Revert. Ctrl - Missing from our Practice:
- 27. 50 © VictorRentea.ro a training by refactoring idea Long-lived Feature Branch Source Control
- 28. 51 © VictorRentea.ro a training by Merge Conflicts Top annoying things in Dev's life: ➢ Interruptions ➢ Refactoring Tests ➢ Long meetings, and
- 29. 52 © VictorRentea.ro a training by Trunk Based Development (requires maturity & discipline) Git Flow (merge conflicts, redo-refactor) Long Branches Inhibit Refactoring if (easyBoxReturnFeature) { // feature under develop } Feature Toggle + incremental DB migrations Preliminary Refactoring (separate Pull-Request)
- 30. 53 © VictorRentea.ro a training by
- 31. 54 © VictorRentea.ro a training by Micro-commits Break a large change set into: Large + Safe Automated Refactoring Manual Refactoring Adding Behavior + Easier Code Review + Less Bugs - Prior Exploration Needed to identify the steps A Commit Message Notation: https://github.com/RefactoringCombos/ArlosCommitNotation Separate Commits, or Preparatory refactoring PR
- 32. 56 © VictorRentea.ro a training by What Stops Refactoring: Recap Fear ➔ tests, pair programming ➔ practice Time ➔ Proper estimates ➔ Improve Effectiveness Rushing even without time pressure Lack of Consensus ➔ team design brainstorm Huge PR - Rejected ➔ Trust ➔ Micro-Commits Fear of Breaking some Eggs to make the omelet Merge Conflicts ➔ short-lived branches ➔ trunk-based YOLO-driven developer A. Make it fun, play together B. Legacy Experience TM Lack of Skills extract a method ?!! ➔ Learn Code Smells Unknown Code Refactoring = Learning
- 33. VictorRentea.ro 57 Worse Code (hours-days) Initial Chaos Code Quality Time You are here The Deepest, most impactful refactoring starts with making a bigger mess "You have to break some eggs to make an omelet" Wow! I see a deep refactoring eg. join two 100-lines method➔ one 200-lines method
- 34. VictorRentea.ro 58 Worse Code (hours-days) Code Quality Time You are here The Strength to Revert (despite emotional involvement) Ctrl- A day without no Ctrl-Z is a day you didn't learned anything ... and the speed to get to some conclusions fast You need
- 35. VictorRentea.ro 60 Code Smells “If it stinks, change it.” — Grandma Beck, discussing childrearing philosophy
- 36. VictorRentea.ro 61 Large Method God Class Too Many Parameters Data Clumps (String, String, Long) ➔ Address > 20 lines > 200 lines > 4 All numbers are arbitrary. Find your own comfort zone
- 37. 65 © VictorRentea.ro a training by Enrich your Domain Language by Discovering Value Objects Simplify your code Constraints Methods Reuse in larger Entities
- 38. VictorRentea.ro 66 Speculative Generality Middle Man person.getAge() int getAge() { return bio.getAge(); } person.getBio().getAge() Data Classes get/set mania ➔ OOP Feature Envy Function ❤️ the state of an object Primitive Obsession ➔ PhoneNumber, OrderId, enum ➔ 💋 KISS Principle
- 39. VictorRentea.ro 67 Primitive Obsession Map<Long, List<Long>> customerIdToOrderIds redeemCoupon(Long, Long, String)
- 40. 68 © VictorRentea.ro a training by Map<Long, List<Long>> customerIdToOrderIds Map<CustomerId, List<OrderId>> orders redeemCoupon(Long, Long, String) redeemCoupon(CustomerId, CouponId, PhoneNumber) Micro-Types
- 41. VictorRentea.ro 69 Primitive Obsession Make concepts explicit by introducing new small classes Even if it's a single String → PhoneNumber Long → CustomerId → ID type: @Value class CustomerId { Long id; } Escape the
- 42. 70 © VictorRentea.ro a training by Map<Long, List<Long>> customerIdToOrderIds If the only usage of a map is: for (Long customerId : map.keySet()) { List<Long> orderIds = map.get(customerId); ... } Code Smell: Iterating over Map Keys List<CustomerOrderIds> You might be missing an abstraction (class): class CustomerOrderIds { private Long customerId; private List<Long> orderId; ... } (or entries)
- 44. VictorRentea.ro 72 Divergent Changes Duplicated Code Shotgun Surgery m() Is it a bug or a feature? <> DRY SRP Is terrible when changes
- 45. VictorRentea.ro 73 switch repeated switches loops for (e : list) { A(); B(); } list.stream()...A.. list.stream()...B.. vs Polymorphism vs "functional" switch in java17 vs enum with logic/Function refs
- 46. VictorRentea.ro 74 Long-Lived Temporary Field x.setX(1); x.doStuff(); out = x.getY(); Temporal Coupling out = x.doStuff(1); Mutable Data + Multi-Threading = reads from X field and writes to Y field
- 47. VictorRentea.ro 75 Code Smells Sheet Defeating the Evil starts with Naming It
- 48. 76 © VictorRentea.ro a training by Code Smells Sheet Defeating the Evil starts with Naming It https://sourcemaking.com/refactoring/smells Long Method God Class Data Clumps Long Parameter List Primitive Obsession Data Class Feature Envy Middle Man Duplicated Code Shotgun Surgery Divergent Code Repeated Switches Loops Temporary Field Long-Lived Mutable Data Speculative Generality Comments Chapter 3 Many more + Solutions in or: https://sourcemaking.com/refactoring/smells
- 49. VictorRentea.ro blog, best talks, training offer @VictorRentea The End victorrentea.ro/community Join me: Stay into The Light sourcemaking.com/refactoring First Half + Ch. 17 Ch.3 Code Smells For rookies Coding Katas kata-log.rocks/refactoring cleancoders.com refactoring.guru Share your thoughts The Beginning