Refactor Like A Boss: A Few Techniques for Everyday Ruby Hacking

Presented by Greg Sterndale. http://promptworks.com

Transcript

1. Refactor Like A Boss a few techniques for everyday Ruby hacking
2. Refactoring The process of changing code without modifying behavior
3. Ungoals of refactoring • Brevity for the sake of brevity • To demonstrate mastery of Ruby or design patterns
4. Goals of refactoring • Improve readability • Improve maintainability • Improve extensibility • Promote an expressive API • Reduce complexity
5. Ruby freebies
6. if 1 > 0 @foo = 'bar' else @foo = 'baz' end ! @foo # => 'bar' DRY Assignment
7. @foo = if 1 > 0 'bar' else 'baz' end ! @foo # => 'bar' DRY Assignment
8. @foo = case 1 when 0..1 'bar' else 'baz' end ! @foo # => 'bar' DRY Assignment
9. @foo = 1 > 0 ? 'bar' : 'qux' ! @foo # => 'bar' Ternary operator
10. def postive?(number) number > 0 ? 'yes' : 'no' end ! positive?(100) # => 'yes' Ternary operator
11. def foo? if @foo true else false end end Bang bang
12. def foo? @foo ? true : false end Bang bang
13. def foo? !!@foo end Bang bang
14. if not @foo @foo = 'bar' end Conditional assignment
15. unless @foo @foo = 'bar' end Conditional assignment
16. @foo = 'bar' unless @foo Conditional assignment
17. @foo ||= 'bar' Conditional assignment
18. Parallel assignment @foo = 'baz' @bar = 'qux' # => "baz" # => "qux"
19. Parallel assignment @foo, @bar = 'baz', 'qux' # => ["baz", "qux"] ! @foo # => "baz"
20. Multiple return def get_with_benchmark(uri) res = nil bench = Benchmark.measure do res = Net::HTTP.get_response(uri) end return res, bench.real end ! @response, @benchmark = get_with_benchmark(@uri) # => [#<Net::HTTPOK 200 OK>, 0.123]
21. def my_safe_method begin do_something_dangerous() true rescue false end end Implied begin
22. def my_safe_method do_something_dangerous() true rescue false end Implied begin
23. def self.likelihood_of_rain Hpricot::XML(weather_xml)/'probability-of-rain' rescue Net::HTTPBadResponse, Net::HTTPHeaderSyntaxError, Net::ProtocolError return false end ! def self.likelihood_of_snow Hpricot::XML(weather_xml)/'probability-of-snow' rescue Net::HTTPBadResponse, Net::HTTPHeaderSyntaxError, Net::ProtocolError return false end Exception lists
24. NET_EXCEPTIONS = [ Net::HTTPBadResponse, Net::HTTPHeaderSyntaxError, Net::ProtocolError ] ! def self.likelihood_of_rain Hpricot::XML(weather_xml)/'probability-of-rain' rescue NET_EXCEPTIONS return false end ! def self.likelihood_of_snow Hpricot::XML(weather_xml)/'probability-of-snow' rescue NET_EXCEPTIONS return false end Exception lists
25. (1..5).map{|number| number.to_s } # => ["1", "2", "3", "4", "5"] Symbol to Proc
26. (1..5).map(&:to_s) # => ["1", "2", "3", "4", "5"] Symbol to Proc
27. def fibonacci_sum sum = 0 [1,1,2,3,5,8,13].each{|int| sum += int } sum end ! fibonacci_sum() # => 33 MapReduce
28. def fibonacci_sum [1,1,2,3,5,8,13].reduce(0){|sum, int| sum + int } end ! fibonacci_sum() # => 33 MapReduce
29. {:foo => 'bar'}.inject({}) do |memo, (key, value)| memo[value] = key memo end ! # => {"bar" => :foo} MapReduce
30. match_data = 'my lil string'.match(/my (\w+) (\w+)/) match_data.captures[0] # => "lil" match_data.captures[1] # => "string" match_data.captures[2] # => nil Regex captures
31. 'my lil string'.match(/my (\w+) (\w+)/) $1 # => "lil" $2 # => "string" $3 # => nil Regex captures
32. 'my lil string' =~ /my (\w+) (\w+)/ $1 # => "lil" $2 # => "string" $3 # => nil Regex captures
33. def Resource.create resource = Resource.new resource.save resource end # => #<Resource:0xffffff> tap
34. def Resource.create Resource.new.tap{|resource| resource.save } end # => #<Resource:0xffffff> tap
35. sprintf("%d as hexadecimal: %04x", 123, 123) # => "123 as hexadecimal: 007b" ! "%d as hexadecimal: %04x" % [123, 123] # => "123 as hexadecimal: 007b" ! "%s string" % ['my'] # => "my string" sprintf
36. def cerealize(val) if val.is_a?(Numeric) || val.is_a?(String) val elsif val.is_a?(Enumerable) val.to_json else val.to_s end end case equality
37. def cerealize(val) case val when Numeric, String val when Enumerable val.to_json else val.to_s end end case equality
38. if command =~ /sudo/ raise 'Danger!' elsif command =~ /^rm / puts 'Are you sure?' else puts 'Run it.' end case equality
39. case command when /sudo/ raise 'Danger!' when /^rm / puts 'Are you sure?' else puts 'Run it.' end case equality
40. Splat Array def shopping_list(ingredients) unless ingredients.is_a?(Array) ingredients = [ingredients] end ingredients.join(", ") end ! shopping_list("eggs") # => "eggs" shopping_list(["eggs", "bacon"]) # => "eggs, bacon"
41. Splat Array def shopping_list(ingredients) [ingredients].flatten.join(", ") end ! shopping_list("eggs") # => "eggs" shopping_list(["eggs", "bacon"]) # => "eggs, bacon" ! !
42. Splat Array def shopping_list(ingredients) [*ingredients].join(", ") end ! shopping_list("eggs") # => "eggs" shopping_list(["eggs", "bacon"]) # => "eggs, bacon" ! !
43. Splat args def shopping_list(*ingredients) ingredients.join(", ") end ! shopping_list("eggs") # => "eggs" shopping_list(["eggs", "bacon"]) # => "eggs, bacon" ! shopping_list("eggs", "bacon") # => "eggs, bacon"
44. Rails freebies
45. if @user.name and !@user.name.empty? puts @user.name else puts "no name" end blank?
46. if @user.name.blank? puts "no name" else puts @user.name end blank?
47. if @user.name.present? puts @user.name else puts "no name" end present?
48. puts @user.name.presence || "no name" presence
49. truncate opening = "A long time ago in a galaxy far, far away" if opening.size > 20 opening[0..16] + "..." end # => "A long time ago i..."
50. truncate opening = "A long time ago in a galaxy far, far away" opening.truncate(20) # => "A long time ago i..." !
51. truncate opening = "A long time ago in a galaxy far, far away" opening.truncate(20, :separator => ' ') # => "A long time ago..." !
52. @existing = User.find_by_email(@new.email) @existing.destroy if @existing try
53. User.find_by_email(@new.email).try(:destroy) try
54. in? if admin_roles.include? @user.role puts "Hi Admin!" end
55. in? if @user.role.in? admin_roles puts "Hi Admin!" end
56. class User ! has_one :account ! def balance self.account.balance end ! def balance=(amount) self.account.balance=(amount) end ! end Delegation
57. class User ! has_one :account ! delegate :balance, :balance=, :to => :account ! end Delegation
58. class Avatar ! def file_size if @file_size return @file_size else result = some_expensive_calculation result += more_expensive_calculation @file_size = result end end ! end Memoization
59. class Avatar ! extend ActiveSupport::Memoizable ! def file_size result = some_expensive_calculation result += more_expensive_calculation end memoize :file_size ! end Memoization
60. ! alias_method :translate_without_log, :translate ! def translate_with_log(*args) result = translate_without_log(*args) Rails.logger.info result result end ! alias_method :translate, :translate_with_log alias_method_chain
61. def translate_with_log(*args) result = translate_without_log(*args) Rails.logger.info result result end ! alias_method_chain :translate, :log alias_method_chain
62. class Resource class < self ! def host=(name) @host = hame end def host @host end ! end end class_attribute
63. class Resource class < self ! attr_accessor :host ! end end class_attribute
64. class Resource ! class_attribute :host ! end class_attribute
65. Hash#symbolize_keys my_hash = { 'foo' => 123 }.symbolize_keys my_hash['foo'] # => nil my_hash[:foo] # => 123
66. Hash#stringify_keys my_hash = { :foo => 123 }.stringify_keys my_hash['foo'] # => 123 my_hash[:foo] # => nil
67. HashWithIndifferentAccess my_hash = { :foo => 123 } my_hash['foo'] # => nil my_hash[:foo] # => 123
68. HashWithIndifferentAccess my_hash = { :foo => 123 }.with_indifferent_access my_hash['foo'] # => 123 my_hash[:foo] # => 123
69. forty_two my_array = [] my_array[41] = "the answer" ! my_array[41] # => "the answer"
70. forty_two my_array = [] my_array[41] = "the answer" ! my_array.forty_two # => "the answer"
71. slideshare github irc
 gsterndale gsterndale sternicus