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. Code smells
Long method
Duplications
Heavy class
Stupid name
Too many params
Feature envy
Ubercallback
Complex conditions

13. Refactoring cycle
Check test
coverage
Write tests
if needed
Change code
Ensure that
tests pass
Check overall
complexity

14. Find code smells
Check test
coverage
Write tests
if needed
Change code
Ensure that
tests pass
Check overall
complexity

15. Check test coverage
Check test
coverage
Write tests
if needed
Change code
Ensure that
tests pass
Check overall
complexity

16. Write new tests if needed
Check test
coverage
Write tests
if needed
Change code
Ensure that
tests pass
Check overall
complexity

17. reFACTOR
Check test
coverage
Write tests
if needed
Change code
Ensure that
tests pass
Check overall
complexity

18. Ensure that tests pass
Check test
coverage
Write tests
if needed
Change code
Ensure that
tests pass
Check overall
complexity

19. Automate tests!
Check test
coverage
Write tests
if needed
Change code
Ensure that
tests pass
Check overall
complexity
Travis CI
Jenkins CI
Gitlab CI

20. Automate complexity analysis?
Check test
coverage
Write tests
if needed
Change code
Ensure that
tests pass
Check overall
complexity

21. Could complexity analysis be
automated?

22. ?
How can we process code?

23. 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

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))))
Sexp operator

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 body

26. Automated analysis
• Long methods
• Complex class
• Stupid variable name

27. 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

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
Count sexp operators

29. 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

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
Cound weights of Sexp operators

31. 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))))

32. Automated analysis

33. Refactoring
!=
Rehacktoring
@katrinyx

34. It is about perception
We READ code, NOT COMPILE it.

35. After this talk do:
• gem install flog
• gem install flay
• gem install reek
• flog PROJECT_PATH
• flay PROJECT_PATH
• reek PROJECT_PATH

36. Let’s refactor!
Anatoli Makarevich
@makaroni4