Refactoring. Ruby edition.Anatoli Makarevich

@makaroni4

Who am I?

Our projects look like

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

Refactoring is

but NOT

writing testschanging code

reducing complexity

adding new features

Refactoring != Moving backwards

To grow fast you need to grow right.

What refactoring does?

ComplexityReadabilityMaintainabilityExtensibility

This is scientific!

Martin Fowler, 1999

Your desk books are:

Code Smell

Any symptom in the source code of a program that possibly indicates a deeper

problemKent Beck

Code smells

Long methodDuplicationsHeavy classStupid name

Too many params

Feature envyUbercallback

Complex conditions

Refactoring cycleCheck testcoverage

Write testsif needed

Change code

Ensure thattests pass

Check overallcomplexity

Find code smellsCheck testcoverage

Write testsif needed

Change code

Ensure thattests pass

Check overallcomplexity

Check test coverageCheck testcoverage

Write testsif needed

Change code

Ensure thattests pass

Check overallcomplexity

Write new tests if neededCheck testcoverage

Write testsif needed

Change code

Ensure thattests pass

Check overallcomplexity

reFACTORCheck testcoverage

Write testsif needed

Change code

Ensure thattests pass

Check overallcomplexity

Ensure that tests passCheck testcoverage

Write testsif needed

Change code

Ensure thattests pass

Check overallcomplexity

Automate tests!Check testcoverage

Write testsif needed

Change code

Ensure thattests pass

Check overallcomplexity

Travis CIJenkins CIGitlab CI

Automate complexity analysis?Check testcoverage

Write testsif needed

Change code

Ensure thattests pass

Check overallcomplexity

Could complexity analysis be automated?

?How can we process code?

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

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

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

Automated analysis

• Long methods

• Complex class

• Stupid variable name

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

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

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

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

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))))

Automated analysis

Refactoring!=

Rehacktoring

@katrinyx

It is about perception

We READ code, NOT COMPILE it.

After this talk do:

• gem install flog

• gem install flay

• gem install reek

• flog PROJECT_PATH

• flay PROJECT_PATH

• reek PROJECT_PATH

Let’s refactor!

Anatoli Makarevich@makaroni4