Refactoring Ruby

Short talk about refactoring and Ruby code complexity analysis.

1. Refactoring. Ruby edition. Anatoli Makarevich @makaroni4
2. Who am I?
3. Our projects look like
4. In next 15 minutes we will • spice up our knowledge about refactoring • look at some common smells • get acquainted with automated code analysis • become ready to refactor
5. Refactoring is but NOT writing tests changing code reducing complexity adding new features
6. Refactoring != Moving backwards
7. To grow fast you need to grow right.
8. What refactoring does? Complexity Readability Maintainability Extensibility
9. This is scientific! Martin Fowler, 1999
10. Your desk books are:
11. Code Smell Any symptom in the source code of a program that possibly indicates a deeper problem Kent Beck
12. Let’s smell it!
13. Code smells Long method Duplications Heavy class Stupid name Too many params Feature envy Ubercallback Complex conditions
14. Refactoring cycle Check test coverage Write tests if needed Change code Ensure that tests pass Check overall complexity
15. Find code smells Check test coverage Write tests if needed Change code Ensure that tests pass Check overall complexity
16. Check test coverage Check test coverage Write tests if needed Change code Ensure that tests pass Check overall complexity
17. Write new tests if needed Check test coverage Write tests if needed Change code Ensure that tests pass Check overall complexity
18. reFACTOR Check test coverage Write tests if needed Change code Ensure that tests pass Check overall complexity
19. Ensure that tests pass Check test coverage Write tests if needed Change code Ensure that tests pass Check overall complexity
20. Automate tests! Check test coverage Write tests if needed Change code Ensure that tests pass Check overall complexity Travis CI Jenkins CI Gitlab CI
21. Automate complexity analysis? Check test coverage Write tests if needed Change code Ensure that tests pass Check overall complexity
22. Could complexity analysis be automated?
23. ? How can we process code?
24. s(:class, :Sexp, s(:const, :Array), s(:defn, :sexp_type, s(:args), s(:call, nil, :first)), s(:defn, :sexp_body, s(:args), s(:call, nil, :[], s(:lit, 1..-1)))) S-expressions
25. s(:class, :Sexp, s(:const, :Array), s(:defn, :sexp_type, s(:args), s(:call, nil, :first)), s(:defn, :sexp_body, s(:args), s(:call, nil, :[], s(:lit, 1..-1)))) Sexp operator
26. s(:class, :Sexp, s(:const, :Array), s(:defn, :sexp_type, s(:args), s(:call, nil, :first)), s(:defn, :sexp_body, s(:args), s(:call, nil, :[], s(:lit, 1..-1)))) Sexp body
27. Automated analysis • Long methods • Complex class • Stupid variable name
28. Long method s(:class, :Sexp, s(:const, :Array), s(:defn, :sexp_type, s(:args), s(:call, nil, :first)), s(:defn, :sexp_body, s(:args), s(:call, nil, :[], s(:lit, 1..-1)))) Find method Sexp :defn
29. Long method s(:class, :Sexp, s(:const, :Array), s(:defn, :sexp_type, s(:args), s(:call, nil, :first)), s(:defn, :sexp_body, s(:args), s(:call, nil, :[], s(:lit, 1..-1)))) Find method Sexp :defn Count sexp operators
30. Complex class s(:class, :Sexp, s(:const, :Array), s(:defn, :sexp_type, s(:args), s(:call, nil, :first)), s(:defn, :sexp_body, s(:args), s(:call, nil, :[], s(:lit, 1..-1)))) Find method Sexp :class
31. Complex class s(:class, :Sexp, s(:const, :Array), s(:defn, :sexp_type, s(:args), s(:call, nil, :first)), s(:defn, :sexp_body, s(:args), s(:call, nil, :[], s(:lit, 1..-1)))) Find method Sexp :class Cound weights of Sexp operators
32. Stupid variable name s(:class, :HomerSimpson, s(:const, :BlahBlahBlah), s(:defn, :donuts, s(:args), s(:call, nil, :fist)), s(:defn, :beersnstuff, s(:args), s(:call, nil, :[], s(:lit, 1..-1))))
33. Automated analysis
34. Refactoring != Rehacktoring @katrinyx
35. It is about perception We READ code, NOT COMPILE it.
36. After this talk do: • gem install flog • gem install flay • gem install reek • flog PROJECT_PATH • flay PROJECT_PATH • reek PROJECT_PATH
37. Let’s refactor! Anatoli Makarevich @makaroni4