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

Confident refactors

Sponsored · Ship Features Fearlessly Turn features on and off without deploys. Used by thousands of Ruby developers. →
Avatar for Mehdi Lahmam B. Mehdi Lahmam B.
June 19, 2017
Technology
160
1

Confident refactors

Avatar for Mehdi Lahmam B.

Mehdi Lahmam B.

June 19, 2017

More Decks by Mehdi Lahmam B.

See All by Mehdi Lahmam B.
Beyond code: Becoming a Product Engineer
Avatar for Mehdi Lahmam B. mehlah
0
67
Possible to measure developer productivity?
Avatar for Mehdi Lahmam B. mehlah
0
75
PG FDW FTW
Avatar for Mehdi Lahmam B. mehlah
0
200
Product culture
Avatar for Mehdi Lahmam B. mehlah
0
100
OpenAPI and AsyncAPI specifications as contracts
Avatar for Mehdi Lahmam B. mehlah
0
710
Technical Debt
Avatar for Mehdi Lahmam B. mehlah
1
330
Data informed growth
Avatar for Mehdi Lahmam B. mehlah
0
280
Serverless Ruby and AWS Lambda
Avatar for Mehdi Lahmam B. mehlah
0
200
Middleware all the things
Avatar for Mehdi Lahmam B. mehlah
2
900

Other Decks in Technology

See All in Technology
[しろおび夏祭り2026] チャットするAIから、作業するAIへ - 使われ方の変化と、その裏側で起きていること
Avatar for kk0n kk0n
0
1.6k
オートロックマンションなのに、各部屋は施錠なし！？ 攻撃者が組織内ネットワークで大暴れする理由 / The Front Door Is Locked, but the Rooms Are Wide Open: Why Attackers Move Freely Inside Enterprise Networks
Avatar for NTT docomo Business nttcom
1
1.6k
社内の7割が使うデータ基盤を、 データチーム2人で回すためにやったこと
Avatar for KOH koh_yoshi
4
980
ボトムアップ文化が強い組織で セキュリティをどう根付かせていくかの現在進行形の話 / Making Security Stick in a Bottom-Up Organization
Avatar for Takashi Yamaguchi yamaguchitk333
0
200
ブラウザ研修 2026
Avatar for Recruit recruitengineers
PRO
4
740
ガバメントクラウドでのランサムウェア対策
Avatar for 高橋広和 techniczna
2
940
Digitization部 紹介資料
Avatar for Sansan, Inc. sansan33
PRO
2
7.7k
個人OSSが、机の上から世界に広がるまでの話
Avatar for Shinya Saita shinyasaita
1
360
SmartHR Engineering Team Deck
Avatar for SmartHR Recruit smarthr
0
260
え？フロントエンドエンジニアの ワイがインフラも！？
Avatar for puku0x puku0x
1
390
SnowflakeCoCoでデータエンジニアリング！
Avatar for numa foursue
0
180
新しい SLO が良い感じにハマっている話
Avatar for kaita z63d
5
2.1k

Featured

See All Featured
SEO in 2025: How to Prepare for the Future of Search
Avatar for Michael King ipullrank
3
3.7k
The MySQL Ecosystem @ GitHub 2015
Avatar for Sam Lambert samlambert
251
13k
Why Your Marketing Sucks and What You Can Do About It - Sophie Logan
Avatar for Sophie Logan marketingsoph
0
360
Applied NLP in the Age of Generative AI
Avatar for Ines Montani inesmontani
PRO
4
2.4k
Ethics towards AI in product and experience design
Avatar for Skipper Chong Warson skipperchong
2
340
The Success of Rails: Ensuring Growth for the Next 100 Years
Avatar for Eileen M. Uchitelle eileencodes
47
8.3k
Organizational Design Perspectives: An Ontology of Organizational Design Elements
Avatar for Dr. Kim W Petersen kimpetersen
PRO
1
790
[Rails World 2023 - Day 1 Closing Keynote] - The Magic of Rails
Avatar for Eileen M. Uchitelle eileencodes
38
2.9k
Lessons Learnt from Crawling 1000+ Websites
Avatar for Charles Meaden charlesmeaden
PRO
1
1.5k
Fight the Zombie Pattern Library - RWD Summit 2016
Avatar for Marcelo Somers marcelosomers
234
17k
Site-Speed That Sticks
Avatar for Harry Roberts csswizardry
13
1.4k
The Spectacular Lies of Maps
Avatar for Per Axbom axbom
PRO
1
890

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