Upgrade to Pro — share decks privately, control downloads, hide ads and more …

Confident refactors

Avatar for Mehdi Lahmam B. Mehdi Lahmam B.
June 19, 2017
Technology
1
120

Confident refactors

Avatar for Mehdi Lahmam B.

Mehdi Lahmam B.

June 19, 2017
Tweet

More Decks by Mehdi Lahmam B.

See All by Mehdi Lahmam B.
Possible to measure developer productivity?
Avatar for Mehdi Lahmam B. mehlah
0
43
PG FDW FTW
Avatar for Mehdi Lahmam B. mehlah
0
160
Product culture
Avatar for Mehdi Lahmam B. mehlah
0
65
OpenAPI and AsyncAPI specifications as contracts
Avatar for Mehdi Lahmam B. mehlah
0
650
Technical Debt
Avatar for Mehdi Lahmam B. mehlah
1
280
Data informed growth
Avatar for Mehdi Lahmam B. mehlah
0
230
Serverless Ruby and AWS Lambda
Avatar for Mehdi Lahmam B. mehlah
0
160
Middleware all the things
Avatar for Mehdi Lahmam B. mehlah
2
850
If only I knew this shit in college
Avatar for Mehdi Lahmam B. mehlah
0
210

Other Decks in Technology

See All in Technology
Function Body Macros で、SwiftUI の View に Accessibility Identifier を自動付与する/Function Body Macros: Autogenerate accessibility identifiers for SwiftUI Views
Avatar for Yuki Miida miichan
2
180
20250913_JAWS_sysad_kobe
Avatar for Takuya Yonezawa takuyay0ne
2
180
5年目から始める Vue3 サイト改善 #frontendo
Avatar for Kihara, Takuya tacck
PRO
3
220
250905 大吉祥寺.pm 2025 前夜祭 「プログラミングに出会って20年、『今』が1番楽しい」
Avatar for Masaya Kudo msykd
PRO
1
820
フルカイテン株式会社 エンジニア向け採用資料
Avatar for FULL KAITEN fullkaiten
0
8.7k
企業の生成AIガバナンスにおけるエージェントとセキュリティ
Avatar for LINEヤフーTech (LY Corporation Tech) lycorptech_jp
PRO
2
160
生成AI時代のデータ基盤設計〜ペースレイヤリングで実現する高速開発と持続性〜 / Levtech Meetup_Session_2
Avatar for Sansan R&D sansan_randd
1
150
KotlinConf 2025_イベントレポート
Avatar for ソニー株式会社 sony
1
130
ZOZOマッチのアーキテクチャと技術構成
Avatar for ZOZO Developers zozotech
PRO
3
1.5k
研究開発と製品開発、両利きのロボティクス
Avatar for Yutaka Kondo youtalk
1
520
BPaaSにおける人と協働する前提のAIエージェント-AWS登壇資料
Avatar for KentaroFujii kentarofujii
0
140
AIエージェント開発用SDKとローカルLLMをLINE Botと組み合わせてみた / LINEを使ったLT大会 #14
Avatar for you（@youtoy） you
PRO
0
110

Featured

See All Featured
The Pragmatic Product Professional
Avatar for Laura Van Doore lauravandoore
36
6.9k
Rails Girls Zürich Keynote
Avatar for Gregor Martynus gr2m
95
14k
Build The Right Thing And Hit Your Dates
Avatar for Maggie C. maggiecrowley
37
2.9k
The Language of Interfaces
Avatar for Des Traynor destraynor
161
25k
How to Ace a Technical Interview
Avatar for Jacob Kaplan-Moss jacobian
279
23k
Agile that works and the tools we love
Avatar for Rasmus Luckow-Nielsen rasmusluckow
330
21k
Save Time (by Creating Custom Rails Generators)
Avatar for Garrett Dimon garrettdimon
PRO
32
1.5k
jQuery: Nuts, Bolts and Bling
Avatar for Doug Neiner dougneiner
64
7.9k
Refactoring Trust on Your Teams (GOTO; Chicago 2020)
Avatar for Rebecca Miller-Webster rmw
34
3.1k
Designing Dashboards & Data Visualisations in Web Apps
Avatar for Des Traynor destraynor
231
53k
Scaling GitHub
Avatar for Zach Holman holman
463
140k
CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again
Avatar for Sam Stephenson sstephenson
162
15k

Transcript

  1. Confident Refactors

  2. Mehdi Lahmam @mehlah

  3. 25kV Rails app, started in Feb 2009 Never rewritten 23k+

    commits from 52 contributors

  4. Ruby is a massively successful language!

  5. Early success Making it easy to make new things

  6. Later success Making it easy to maintain old things

  7. Today, let’s refactor some legacy code

  8. Today, let’s refactor some legacy code

  9. Refactor - verb To change the design of code without

    changing its observable behavior.

  10. Refactor - verb To change in advance of a new

    feature or bug fix, making the job easier.

  11. Today, let’s refactor some legacy code

  12. Legacy - noun Old code.

  13. Legacy - noun Code without tests.

  14. Legacy - noun Code that we don’t like.

  15. Legacy - noun Code we don’t understand well enough
 to

    change confidently.

  16. Today, let’s refactor some legacy code

  17. Refactoring is hard

  18. Refactoring legacy code is very hard

  19. Easy to accidentally break functionality

  20. Legacy refactors feels unsafe

  21. Legacy refactors are hard to sell

  22. Business priority Cost / risks

  23. Business priority Cost / risks New features

  24. Business priority Cost / risks New features Bugs fixes

  25. Business priority Cost / risks New features Bugs fixes Testing

  26. Business priority Cost / risks New features Bug fixes Testing

    Refactoring

  27. Business priority Cost / risks New features Bug fixes Testing

    Refactoring no selling needed easy to sell can often sell very hard to sell

  28. Selling refactoring is hard ⏲ ⛔

  29. Business priority Cost / risks Refactoring

  30. Too much pressure ⏳ ⚒

  31. Refactors are scary

  32. What techniques we have? PDD - Pray Driven Development Fowler’s

    refactoring book Characterization testing A/B testing, experiments

  33. Refactors as surgeries

  34. Refactors as surgeries Requires careful planning Follow a clear process

    Multiple observations Flexible tools Things can get bloody

  35. 1. Plan 2. Cut 3. Record 4. Validate 5. Refactor

    6. Verify 7. Compare 8. Fallback 9. Delete Clear process
  36. None
  37. None
  38. None

  39. Cut

  40. Record

  41. Validate ✅

  42. Refactor <Insert magic here />

  43. Verify

  44. Compare ⚖

  45. Fallback

  46. Delete ✂

  47. We dit it

  48. We dit it Time to celebrate hard