Confident refactors

Transcript

1. Confident Refactors
   

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2. Mehdi Lahmam
   @mehlah
   

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3. 25kV
   Rails app, started in Feb 2009
   Never rewritten
   23k+ commits from 52 contributors
   

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4. Ruby is a massively
   successful language!
   

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5. Early success
   Making it easy to make new things
   

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6. Later success
   Making it easy to maintain old things
   

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7. Today, let’s refactor
   some legacy code
   

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8. Today, let’s refactor
   some legacy code
   

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9. Refactor - verb
   To change the design of code
   without changing its observable behavior.
   

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10. Refactor - verb
    To change in advance of a new feature
    or bug fix, making the job easier.
    

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11. Today, let’s refactor
    some legacy code
    

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12. Legacy - noun
    Old code.
    

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13. Legacy - noun
    Code without tests.
    

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

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

    to change confidently.
    

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16. Today, let’s refactor
    some legacy code
    

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17. Refactoring is hard
    

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18. Refactoring legacy code
    is very hard
    

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19. Easy to accidentally
    break functionality
    

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20. Legacy refactors
    feels unsafe
    

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21. Legacy refactors
    are hard to sell
    

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22. Business priority
    Cost / risks
    

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23. Business priority
    Cost / risks
    New features
    

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24. Business priority
    Cost / risks
    New features
    Bugs fixes
    

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

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

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27. Business priority
    Cost / risks
    New features
    Bug fixes
    Testing Refactoring
    no selling
    needed
    easy to sell
    can often sell
    very hard to sell
    

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28. Selling refactoring is hard
    ⏲ ⛔
    

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29. Business priority
    Cost / risks
    Refactoring
    

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30. Too much pressure
    ⏳ ⚒
    

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31. Refactors are scary
    
    

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32. What techniques we have?
    PDD - Pray Driven Development
    Fowler’s refactoring book
    Characterization testing
    A/B testing, experiments
    

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33. Refactors as surgeries
    

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34. Refactors as surgeries
    Requires careful planning
    Follow a clear process
    Multiple observations
    Flexible tools
    Things can get bloody
    

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35. 1. Plan
    2. Cut
    3. Record
    4. Validate
    5. Refactor
    6. Verify
    7. Compare
    8. Fallback
    9. Delete
    Clear process
    

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39. Cut
    

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40. Record
    

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41. Validate ✅
    

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42. Refactor
    
    

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43. Verify
    

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44. Compare ⚖
    

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45. Fallback
    

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46. Delete ✂
    

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47. We dit it
    

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48. We dit it
    Time to celebrate hard
    

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