Confident refactors

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
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