Writing small classes is hard. You know you should, but how? It's so much easier to write a large class. In this talk we'll build up a set of small classes starting from nothing using a set of directed refactorings applied as we build, all while keeping our tests green. We'll identify abstractions yearning to be free of their big class cages. In the process we'll also see how basic patterns such as composition, delegation and dependency inversion emerge from using small objects.

1. Enable Labs @mark_menard
#smallcode
Small Code
Mark Menard
RailsConf 2014!
April 24, 2014
@mark_menard !
Enable Labs
Refactoring to Small Code 16x9 - April 24, 2014

2. Enable Labs @mark_menard
#smallcode
‘The great thing about writing
shitty code that “just works,”
is that it is too risky and too
expensive to change, so it
lives forever.’!
!
!
-Reginald Braithwaite @raganwald
Refactoring to Small Code 16x9 - April 24, 2014

3. Enable Labs @mark_menard
#smallcode
What do I mean by small?
Refactoring to Small Code 16x9 - April 24, 2014

4. Enable Labs @mark_menard
#smallcode
It’s not
about total
line count.
Refactoring to Small Code 16x9 - April 24, 2014

5. Enable Labs @mark_menard
#smallcode
It’s not about
method
count.
Refactoring to Small Code 16x9 - April 24, 2014

6. Enable Labs @mark_menard
#smallcode
It’s not
about class
count.
Refactoring to Small Code 16x9 - April 24, 2014

7. Enable Labs @mark_menard
#smallcode
It’s About
Small methods! Small classes
Refactoring to Small Code 16x9 - April 24, 2014

8. Enable Labs @mark_menard
#smallcode
Why should we strive for small code?
Refactoring to Small Code 16x9 - April 24, 2014

9. Enable Labs @mark_menard
#smallcode
We don’t know what the future will bring.
Refactoring to Small Code 16x9 - April 24, 2014

10. Enable Labs @mark_menard
#smallcode
Raise the level of abstraction.
Refactoring to Small Code 16x9 - April 24, 2014

11. Enable Labs @mark_menard
#smallcode
Create composable objects.
Refactoring to Small Code 16x9 - April 24, 2014

12. Enable Labs @mark_menard
#smallcode
Enable Future Change
Refactoring to Small Code 16x9 - April 24, 2014

13. Enable Labs @mark_menard
#smallcode
The goal: Small units of
understandable code that
are amenable to change.
Refactoring to Small Code 16x9 - April 24, 2014

14. Enable Labs @mark_menard
#smallcode
Our Primary Tools
• Extract Method!
• Move Method!
• Extract Class
Refactoring to Small Code 16x9 - April 24, 2014

15. Enable Labs @mark_menard
#smallcode
Let’s Look at Some Code
Refactoring to Small Code 16x9 - April 24, 2014

16. Enable Labs @mark_menard
#smallcode
# some_ruby_program -v
Refactoring to Small Code 16x9 - April 24, 2014

17. Enable Labs @mark_menard
#smallcode
options = CommandLineOptions.new(ARGV) do
option :c
option :v
option :e
end
Refactoring to Small Code 16x9 - April 24, 2014

18. Enable Labs @mark_menard
#smallcode
if options.has(:c)
# Do something
end
!
if options.has(:v)
# Do something else
end
!
if options.has(:e)
# Do the other thing
end
Refactoring to Small Code 16x9 - April 24, 2014

19. Enable Labs @mark_menard
#smallcode# some_ruby_program -v
!
options = CommandLineOptions.new(ARGV) do
option :c
option :v
option :e
end
!
if options.has(:c)
# Do something
end
!
if options.has(:v)
# Do something else
end
!
if options.has(:e)
# Do the other thing
end
Refactoring to Small Code 16x9 - April 24, 2014

20. Enable Labs @mark_menard
#smallcode
describe CommandLineOptions do
!
describe 'options' do
!
let(:parser) { CommandLineOptions.new { option :c } }
!
it "are true if present" do …
!
it "are false if absent" do …
end
end
Refactoring to Small Code 16x9 - April 24, 2014

21. Enable Labs @mark_menard
#smallcode
CommandLineOptions
options
are true if present
are false if absent
!
Finished in 0.00206 seconds
2 examples, 2 failures
Refactoring to Small Code 16x9 - April 24, 2014

22. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = []
@argv = argv
instance_eval &block
end
!
def has (option_flag)
options.include?(option_flag) && argv.include?("-#{option_flag}")
end
!
def option (option_flag)
options << option_flag
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

23. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = []
@argv = argv
instance_eval &block
end
!
def has (option_flag)
options.include?(option_flag) && argv.include?("-#{option_flag}")
end
!
def option (option_flag)
options << option_flag
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

24. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = []
@argv = argv
instance_eval &block
end
!
def has (option_flag)
options.include?(option_flag) && argv.include?("-#{option_flag}")
end
!
def option (option_flag)
options << option_flag
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

25. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = []
@argv = argv
instance_eval &block
end
!
def has (option_flag)
options.include?(option_flag) && argv.include?("-#{option_flag}")
end
!
def option (option_flag)
options << option_flag
end
!
end
options = CommandLineOptions.new(ARGV) do
option :c
option :v
option :e
end
Refactoring to Small Code 16x9 - April 24, 2014

26. Enable Labs @mark_menard
#smallcode
CommandLineOptions
options
are true if present
are false if absent
!
Finished in 0.00206 seconds
2 examples, 0 failures
Refactoring to Small Code 16x9 - April 24, 2014

27. Enable Labs @mark_menard
#smallcode
Done!
Refactoring to Small Code 16x9 - April 24, 2014

28. Enable Labs @mark_menard
#smallcode
% some_ruby_program -v -sfoo
Refactoring to Small Code 16x9 - April 24, 2014

29. Enable Labs @mark_menard
#smallcode
options = CommandLineOptions.new(ARGV) do
option :v
option :s, :string
end
Refactoring to Small Code 16x9 - April 24, 2014

30. Enable Labs @mark_menard
#smallcode
if options.valid?
if options.value(:v)
# Do something
end
!
if (s_option = options.value(:s))
# Do something
end
end
Refactoring to Small Code 16x9 - April 24, 2014

31. Enable Labs @mark_menard
#smallcode
if options.valid?
if options.value(:v)
# Do something
end
!
if (s_option = options.value(:s))
# Do something
end
end
Refactoring to Small Code 16x9 - April 24, 2014

32. Enable Labs @mark_menard
#smallcode
if options.valid?
if options.value(:v)
# Do something
end
!
if (s_option = options.value(:s))
# Do something
end
end
Refactoring to Small Code 16x9 - April 24, 2014

33. Enable Labs @mark_menard
#smallcode
# some_ruby_program -v -sfoo
!
options = CommandLineOptions.new(ARGV) do
option :v
option :s, :string
end
!
if options.valid?
if options.value(:v)
# Do something
end
!
if (s_option = options.value(:s))
# Do something
end
end
Refactoring to Small Code 16x9 - April 24, 2014

34. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = {}
@argv = argv
instance_eval &block
end
!
def option (option_flag, option_type = :boolean)
options[option_flag] = option_type
end
!
def valid?
options.each do |option_flag, option_type|
raw_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return false if option_type == :string && raw_value && raw_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

35. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
def initialize (argv = [], &block)
@options = {}
@argv = argv
instance_eval &block
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

36. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return false if option_type == :string &&
raw_value && raw_value.length < 3
end
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

37. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
!
def value (option_flag)
raw_option_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

38. Enable Labs @mark_menard
#smallcode
CommandLineOptions
boolean options
are true if present
are false if absent
string options
must have content
are valid if there is content
are valid if not in argv
can return the value
return nil if not in argv
!
Finished in 0.00401 seconds
7 examples, 0 failures
Refactoring to Small Code 16x9 - April 24, 2014

39. Enable Labs @mark_menard
#smallcode
Methods
Refactoring to Small Code 16x9 - April 24, 2014

40. Enable Labs @mark_menard
#smallcode
The first rule of methods:
Refactoring to Small Code 16x9 - April 24, 2014

41. Enable Labs @mark_menard
#smallcode
Do one thing. Do it well. Do only that thing.
Refactoring to Small Code 16x9 - April 24, 2014

42. Enable Labs @mark_menard
#smallcode
One level of abstraction per method.
Refactoring to Small Code 16x9 - April 24, 2014

43. Enable Labs @mark_menard
#smallcode
Use Descriptive Names
Refactoring to Small Code 16x9 - April 24, 2014

44. Enable Labs @mark_menard
#smallcode
The fewer arguments the better.
Refactoring to Small Code 16x9 - April 24, 2014

45. Enable Labs @mark_menard
#smallcode
Separate Queries from Commands
Refactoring to Small Code 16x9 - April 24, 2014

46. Enable Labs @mark_menard
#smallcode
Don’t RepeatYourself
Refactoring to Small Code 16x9 - April 24, 2014

47. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return false if option_type == :string && raw_value && raw_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

48. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return false if option_type == :string && raw_value && raw_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

49. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return false if option_type == :string && raw_value && raw_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

50. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return false if option_type == :string && raw_value && raw_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

51. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return false if option_type == :string && raw_value && raw_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

52. Enable Labs @mark_menard
#smallcode
Extract Method Refactoring
def print_invoice_for_amount (amount)
print_header
puts "Name: #{@name}"
puts "Amount: #{amount}"
end
Refactoring to Small Code 16x9 - April 24, 2014

53. Enable Labs @mark_menard
#smallcode
Extract Method Refactoring
def print_invoice_for_amount (amount)
print_header
puts "Name: #{@name}"
puts "Amount: #{amount}"
end
High level of abstraction
Refactoring to Small Code 16x9 - April 24, 2014

54. Enable Labs @mark_menard
#smallcode
Extract Method Refactoring
def print_invoice_for_amount (amount)
print_header
puts "Name: #{@name}"
puts "Amount: #{amount}"
end
Low level of abstraction
Refactoring to Small Code 16x9 - April 24, 2014

55. Enable Labs @mark_menard
#smallcode
Extract Method Refactoring
def print_invoice_for_amount (amount)
print_header
puts "Name: #{@name}"
puts "Amount: #{amount}"
end
def print_invoice_for_amount (amount)
print_header
print_details (amount)
end
!
def print_details (amount)
puts "Name: #{@name}"
puts "Amount: #{amount}"
end
Move this to here
Refactoring to Small Code 16x9 - April 24, 2014

56. Enable Labs @mark_menard
#smallcode
Extract Method Refactoring
def print_invoice_for_amount (amount)
print_header
puts "Name: #{@name}"
puts "Amount: #{amount}"
end
def print_invoice_for_amount (amount)
print_header
print_details (amount)
end
!
def print_details (amount)
puts "Name: #{@name}"
puts "Amount: #{amount}"
end
Same level of abstraction
Move this to here
Refactoring to Small Code 16x9 - April 24, 2014

57. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return false if option_type == :string && raw_value && raw_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

58. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return false if option_type == :string && raw_value && raw_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = argv.find { |arg| arg =~ /^-#{option_flag}/ }
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

59. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if option_type == :string && raw_option_value && raw_option_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
def raw_value_for_option (option_flag)
argv.find { |arg| arg =~ /^-#{option_flag}/ }
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

60. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if option_type == :string && raw_option_value && raw_option_value.length < 3
end
end
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
end
!
def raw_value_for_option (option_flag)
argv.find { |arg| arg =~ /^-#{option_flag}/ }
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

61. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if option_type == :string && !string_option_valid?(raw_option_value)
end
end
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return extract_content(raw_option_value) if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

62. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if option_type == :string && !string_option_valid?(raw_option_value)
end
end
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return extract_content(raw_option_value) if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

63. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if option_type == :string && !string_option_valid?(raw_option_value)
end
end
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return extract_content(raw_option_value) if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

64. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if option_type == :string && !string_option_valid?(raw_option_value)
end
end
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return extract_content(raw_option_value) if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

65. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if option_type == :string && !string_option_valid?(raw_option_value)
end
end
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return extract_content(raw_option_value) if option_type == :string
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

66. Enable Labs @mark_menard
#smallcode
# some_ruby_program -v -efoo -i100
!
options = CommandLineOptions.new(ARGV) do
option :v
option :e, :string
option :i, :integer
end
!
verbose = options.value(:v)
expression = options.value(:e)
iteration_count = options.value(:i) || 1
Refactoring to Small Code 16x9 - April 24, 2014

67. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = {}
@argv = argv
instance_eval &block
end
!
def option (option_flag, option_type = :boolean)
options[option_flag] = option_type
end
!
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if (option_type == :string || option_type == :integer) &&
raw_option_value && raw_option_value.length < 3
return false if option_type == :integer && raw_option_value &&
!(Integer(raw_option_value[2..-1]) rescue false)
end
end
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
return (Integer(raw_option_value[2..-1])) if option_type == :integer
end
!
private def raw_value_for_option (option_flag)
argv.find { |arg| arg =~ /^-#{option_flag}/ }
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

68. Enable Labs @mark_menard
#smallcodeCommandLineOptions
boolean options
are true if present
are false if absent
string options
must have content
are valid if there is content
are valid if not in argv
can return the value
return nil if not in argv
integer options
must have content
are valid if there is content and it's an integer
are invalid if the content is not an integer
are valid if not in argv
can return the value
return nil if not in argv
!
Finished in 0.00338 seconds
13 examples, 0 failures
Refactoring to Small Code 16x9 - April 24, 2014

69. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if (option_type == :string || option_type == :integer) &&
raw_option_value && raw_option_value.length < 3
return false if option_type == :integer && raw_option_value &&
!(Integer(raw_option_value[2..-1]) rescue false)
end
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

70. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if (option_type == :string || option_type == :integer) &&
raw_option_value && raw_option_value.length < 3
return false if option_type == :integer && raw_option_value &&
!(Integer(raw_option_value[2..-1]) rescue false)
end
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

71. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
!
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
return false if (option_type == :string || option_type == :integer) &&
raw_option_value && raw_option_value.length < 3
return false if option_type == :integer && raw_option_value &&
!(Integer(raw_option_value[2..-1]) rescue false)
end
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

72. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
return (Integer(raw_option_value[2..-1])) if option_type == :integer
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

73. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
return (Integer(raw_option_value[2..-1])) if option_type == :integer
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

74. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
return (Integer(raw_option_value[2..-1])) if option_type == :integer
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

75. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
…
!
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
return false if raw_option_value && raw_option_value.length < 3
when :integer
return false if raw_option_value && raw_option_value.length < 3
return false if raw_option_value &&
!(Integer(raw_option_value[2..-1]) rescue false)
end
end
end
!
…
end
Refactoring to Small Code 16x9 - April 24, 2014

76. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
…
!
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
raw_option_value[2..-1]
when :integer
(Integer(raw_option_value[2..-1]))
when :boolean
return true if option_type == :boolean && raw_option_value
end
end
!
…
end
Refactoring to Small Code 16x9 - April 24, 2014

77. Enable Labs @mark_menard
#smallcode
How do we write small classes?
Refactoring to Small Code 16x9 - April 24, 2014

78. Enable Labs @mark_menard
#smallcode
What are the characteristics of a small class?
Refactoring to Small Code 16x9 - April 24, 2014

79. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = {}
@argv = argv
instance_eval &block
end
!
def valid?
options.all?(&:valid)
end
!
def value (option_flag)
options[option_flag].value
end
!
private
def option (option_flag, option_type = :boolean)
options[option_flag] = build_option(option_flag, option_type)
end
!
def build_option
# Need to write this.
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

80. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = {}
@argv = argv
instance_eval &block
end
!
def valid?
options.all?(&:valid)
end
!
def value (option_flag)
options[option_flag].value
end
!
private
def option (option_flag, option_type = :boolean)
options[option_flag] = build_option(option_flag, option_type)
end
!
def build_option
# Need to write this.
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

81. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.all?(&:valid?)
end
!
def value (option_flag)
options[option_flag].value
end
!
def build_option
# Need to write this.
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

82. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.all?(&:valid?)
end
!
def value (option_flag)
options[option_flag].value
end
!
def build_option
# Need to write this.
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

83. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.all?(&:valid?)
end
!
def value (option_flag)
options[option_flag].value
end
!
def build_option
# Need to write this.
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

84. Enable Labs @mark_menard
#smallcodeclass CommandLineOptions
!
…
!
def valid?
options.all?(&:valid?)
end
!
def value (option_flag)
options[option_flag].value
end
!
def build_option
# Need to write this.
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

85. Enable Labs @mark_menard
#smallcode
Dependencies
Refactoring to Small Code 16x9 - April 24, 2014

86. Enable Labs @mark_menard
#smallcode
Dependencies
Command
Line Options ?*
Refactoring to Small Code 16x9 - April 24, 2014

87. Enable Labs @mark_menard
#smallcode
Depend on Abstractions
Refactoring to Small Code 16x9 - April 24, 2014

88. Enable Labs @mark_menard
#smallcode
Command
Line Options
String Option
Integer
Option
Boolean
Option
valid?
value
Option*
Depend on Abstractions
Refactoring to Small Code 16x9 - April 24, 2014

89. Enable Labs @mark_menard
#smallcode
Command
Line Options
String Option
Integer
Option
Boolean
Option
valid?
value
Option*
This is my duck type!
Depend on Abstractions
Refactoring to Small Code 16x9 - April 24, 2014

90. Enable Labs @mark_menard
#smallcode
Command
Line Options
String Option
Integer
Option
Boolean
Option
valid?
value
Option*
This is my duck type!
These are my concrete types.
Depend on Abstractions
Refactoring to Small Code 16x9 - April 24, 2014

91. Enable Labs @mark_menard
#smallcode
Command
Line Options
String Option
Integer
Option
Boolean
Option
valid?
value
Option*
These are my concrete types.
Depend on this!
Depend on Abstractions
Refactoring to Small Code 16x9 - April 24, 2014

92. Enable Labs @mark_menard
#smallcode
Command
Line Options
String Option
Integer
Option
Boolean
Option
valid?
value
Option*
Depend on this!
Don’t depend on these!
Depend on Abstractions
Refactoring to Small Code 16x9 - April 24, 2014

93. Enable Labs @mark_menard
#smallcode
private def option (option_flag, option_type = :boolean)
options[option_flag] = case (option_type)
when :boolean
return BooleanOption.new(option_flag, nil)
when :string
return StringOption.new(option_flag, nil)
when :integer
return IntegerOption.new(option_flag, nil)
end
end
Refactoring to Small Code 16x9 - April 24, 2014

94. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
…
!
def build_option (option_flag, option_type)
“#{option_type}_option".camelize.constantize.new(
option_flag, raw_value_for_option(option_flag)
)
end
!
…
!
end
Refactoring to Small Code 16x9 - April 24, 2014

95. Enable Labs @mark_menard
#smallcodeclass Option
!
attr_reader :flag, :raw_value
!
def initialize (flag, raw_value)
@flag = flag
@raw_value = raw_value
end
!
def valid?
end
!
def value
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

96. Enable Labs @mark_menard
#smallcodeclass BooleanOption < Option
!
def valid?
true
end
!
def value
raw_value
end
end
class Option
!
attr_reader :flag, :raw_value
!
def initialize (flag, raw_value)
@flag = flag
@raw_value = raw_value
end
!
def valid?
end
!
def value
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

97. Enable Labs @mark_menard
#smallcodeclass StringOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
class IntegerOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
Refactoring to Small Code 16x9 - April 24, 2014

98. Enable Labs @mark_menard
#smallcodedef valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
!
!
when :integer
!
!
!
end
end
end
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
return false if raw_option_value &&
raw_option_value.length < 3
when :integer
return false if raw_option_value
&& raw_option_value.length < 3
return false if raw_option_value &&
!(Integer(raw_option_value[2..-1]) rescue false)
end
end
end
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
!
when :integer
!
when :boolean
!
end
end
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
raw_option_value[2..-1]
when :integer
(Integer(raw_option_value[2..-1]))
when :boolean
return true if option_type == :boolean && raw_option_value
end
end
class StringOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
!
!
!
end
!
def value
!
!
end
end
Refactoring to Small Code 16x9 - April 24, 2014

99. Enable Labs @mark_menard
#smallcodedef valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
!
!
when :integer
!
!
!
end
end
end
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
!
when :integer
!
when :boolean
!
end
end
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
raw_option_value[2..-1]
when :integer
(Integer(raw_option_value[2..-1]))
when :boolean
return true if option_type == :boolean && raw_option_value
end
end
class StringOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
!
!
!
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
!
!
end
end
Refactoring to Small Code 16x9 - April 24, 2014

100. Enable Labs @mark_menard
#smallcodedef valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
!
!
when :integer
!
!
!
end
end
end
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
!
when :integer
!
when :boolean
!
end
end
class StringOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
!
!
!
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
return nil unless raw_value
raw_value[2..-1]
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
return nil unless raw_value
Integer(raw_value[2..-1])
end
end
Refactoring to Small Code 16x9 - April 24, 2014

101. Enable Labs @mark_menard
#smallcodedef valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
!
!
when :integer
!
!
!
end
end
end
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
!
when :integer
!
when :boolean
!
end
end
class StringOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
!
!
!
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
return nil unless raw_value
raw_value[2..-1]
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
return nil unless raw_value
Integer(raw_value[2..-1])
end
end
Refactoring to Small Code 16x9 - April 24, 2014

102. Enable Labs @mark_menard
#smallcodedef valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
!
!
when :integer
!
!
!
end
end
end
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
!
when :integer
!
when :boolean
!
end
end
class StringOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
!
!
!
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
return nil unless raw_value
raw_value[2..-1]
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
return nil unless raw_value
Integer(raw_value[2..-1])
end
end
Refactoring to Small Code 16x9 - April 24, 2014

103. Enable Labs @mark_menard
#smallcode
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
!
when :integer
!
when :boolean
!
end
end
class StringOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
!
!
!
end
!
def value
!
!
end
end
def valid?
options.all?(&:valid?)
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
return nil unless raw_value
raw_value[2..-1]
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
return nil unless raw_value
Integer(raw_value[2..-1])
end
end
Refactoring to Small Code 16x9 - April 24, 2014

104. Enable Labs @mark_menard
#smallcode
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
!
return case(option_type)
when :string
!
when :integer
!
when :boolean
!
end
end
class StringOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
!
!
!
end
!
def value
!
!
end
end
def valid?
options.all?(&:valid?)
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
return nil unless raw_value
raw_value[2..-1]
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
return nil unless raw_value
Integer(raw_value[2..-1])
end
end
Refactoring to Small Code 16x9 - April 24, 2014

105. Enable Labs @mark_menard
#smallcode
def value (option_flag)
options[option_flag].value
end
class StringOption < Option
!
def valid?
!
!
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
!
!
!
end
!
def value
!
!
end
end
def valid?
options.all?(&:valid?)
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
!
!
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
!
!
end
end
class StringOption < Option
!
def valid?
return true unless raw_value
raw_value && raw_value.length > 2
end
!
def value
return nil unless raw_value
raw_value[2..-1]
end
end
!
class IntegerOption < Option
!
def valid?
return true unless raw_value
(raw_value && raw_value.length > 2) &&
(Integer(raw_value[2..-1]) rescue false)
end
!
def value
return nil unless raw_value
Integer(raw_value[2..-1])
end
end
Refactoring to Small Code 16x9 - April 24, 2014

106. Enable Labs @mark_menard
#smallcode
Option classes
Option
stores it's flag
stores it's raw value
BooleanOption
is true if the raw value is present
is false if the raw value is nil
is valid
StringOption
invalid when there is no content
is valid if there is content
is valid if raw value is nil
can return the value
value is nil if raw value is nil
IntegerOption
is invalid without content
is invalid if the content is not an integer
is valid if there is content and it's an integer
is valid if raw value is nil
can return the value
returns nil if raw value is nil
!
Finished in 0.00495 seconds
22 examples, 0 failures, 6 pending
Refactoring to Small Code 16x9 - April 24, 2014

107. Enable Labs @mark_menard
#smallcode
How do we isolate abstractions?
Separate the “what”
from the “how”.
Refactoring to Small Code 16x9 - April 24, 2014

108. Enable Labs @mark_menard
#smallcode
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
return false if raw_option_value && raw_option_value.length < 3
when :integer
return false if raw_option_value && raw_option_value.length < 3
return false if raw_option_value && !(Integer(raw_option_value[2..-1]) rescue false)
end
end
end
Refactoring to Small Code 16x9 - April 24, 2014

109. Enable Labs @mark_menard
#smallcode
def valid?
options.values.all?(&:valid?)
end
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
return false if raw_option_value && raw_option_value.length < 3
when :integer
return false if raw_option_value && raw_option_value.length < 3
return false if raw_option_value && !(Integer(raw_option_value[2..-1]) rescue false)
end
end
end
Refactoring to Small Code 16x9 - April 24, 2014

110. Enable Labs @mark_menard
#smallcode
def valid?
options.values.all?(&:valid?)
end
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
return false if raw_option_value && raw_option_value.length < 3
when :integer
return false if raw_option_value && raw_option_value.length < 3
return false if raw_option_value && !(Integer(raw_option_value[2..-1]) rescue false)
end
end
end
This all about HOW!
Refactoring to Small Code 16x9 - April 24, 2014

111. Enable Labs @mark_menard
#smallcode
def valid?
options.values.all?(&:valid?)
end
def valid?
options.each do |option_flag, option_type|
raw_option_value = raw_value_for_option(option_flag)
!
case(option_type)
when :string
return false if raw_option_value && raw_option_value.length < 3
when :integer
return false if raw_option_value && raw_option_value.length < 3
return false if raw_option_value && !(Integer(raw_option_value[2..-1]) rescue false)
end
end
end
This all about HOW!
This is WHAT I want done.
Refactoring to Small Code 16x9 - April 24, 2014

112. Enable Labs @mark_menard
#smallcode
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
return (Integer(raw_option_value[2..-1])) if option_type == :integer
end
Refactoring to Small Code 16x9 - April 24, 2014

113. Enable Labs @mark_menard
#smallcode
def value (option_flag)
options[option_flag].value
end
def value (option_flag)
raw_option_value = raw_value_for_option(option_flag)
return nil unless raw_option_value
option_type = options[option_flag]
return true if option_type == :boolean && raw_option_value
return raw_option_value[2..-1] if option_type == :string
return (Integer(raw_option_value[2..-1])) if option_type == :integer
end
Refactoring to Small Code 16x9 - April 24, 2014

114. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = {}
@argv = argv
instance_eval &block
end
!
def valid?
options.values.all?(&:valid?)
end
!
def value (option_flag)
options[option_flag].value
end
!
private
!
def option (option_flag, option_type = :boolean)
options[option_flag] = build_option(option_flag, option_type)
end
!
def build_option (option_flag, option_type)
"#{option_type}_option".camelize.constantize.new(option_flag, raw_value_for_option(option_flag))
end
!
def raw_value_for_option (option_flag)
argv.find { |arg| arg =~ /^-#{option_flag}/ }
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

115. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = {}
@argv = argv
instance_eval &block
end
!
def valid?
options.values.all?(&:valid?)
end
!
def value (option_flag)
options[option_flag].value
end
!
private
!
def option (option_flag, option_type = :boolean)
options[option_flag] = build_option(option_flag, option_type)
end
!
def build_option (option_flag, option_type)
"#{option_type}_option".camelize.constantize.new(option_flag, raw_value_for_option(option_flag))
end
!
def raw_value_for_option (option_flag)
argv.find { |arg| arg =~ /^-#{option_flag}/ }
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

116. Enable Labs @mark_menard
#smallcode
class CommandLineOptions
!
attr_accessor :argv
attr_reader :options
!
def initialize (argv = [], &block)
@options = {}
@argv = argv
instance_eval &block
end
!
def valid?
options.values.all?(&:valid?)
end
!
def value (option_flag)
options[option_flag].value
end
!
private
!
def option (option_flag, option_type = :boolean)
options[option_flag] = build_option(option_flag, option_type)
end
!
def build_option (option_flag, option_type)
"#{option_type}_option".camelize.constantize.new(option_flag, raw_value_for_option(option_flag))
end
!
def raw_value_for_option (option_flag)
argv.find { |arg| arg =~ /^-#{option_flag}/ }
end
!
end
Refactoring to Small Code 16x9 - April 24, 2014

117. Enable Labs @mark_menard
#smallcode
!
def valid?
options.values.all?(&:valid?)
end
!
def value (option_flag)
options[option_flag].value
end
Refactoring to Small Code 16x9 - April 24, 2014

118. Enable Labs @mark_menard
#smallcode
CommandLineOptions
builds an option object for each defined option
is valid if all options are valid
is invalid if any option is invalid
option object conventions
uses a StringOption for string options
uses a BooleanOption for boolean options
uses an IntegerOption for integer options
Refactoring to Small Code 16x9 - April 24, 2014

119. Enable Labs @mark_menard
#smallcode
Then
Refactoring to Small Code 16x9 - April 24, 2014

120. Enable Labs @mark_menard
#smallcode
some_ruby_program -v -efoo -i100 -afoo,bar,baz
Refactoring to Small Code 16x9 - April 24, 2014

121. Enable Labs @mark_menard
#smallcode
describe "array options" do
it "can return the value as an array" do
options = CommandLineOptions.new([ "-afoo,bar,baz" ]) { option :a, :array }
expect(options.value(:a)).to eq(["foo", "bar", "baz"])
end
end
Refactoring to Small Code 16x9 - April 24, 2014

122. Enable Labs @mark_menard
#smallcode
describe "array options" do
it "can return the value as an array" do
options = CommandLineOptions.new([ "-afoo,bar,baz" ]) { option :a, :array }
expect(options.value(:a)).to eq(["foo", "bar", "baz"])
end
end
class ArrayOption < OptionWithContent
def value
return nil if option_unset?
extract_value_from_raw_value.split(",")
end
end
Refactoring to Small Code 16x9 - April 24, 2014

123. Enable Labs @mark_menard
#smallcodeCommandLineOptions
boolean options
are true if present
are false if absent
string options
must have content
is valid when there is content
can return the value
return nil if not in argv
integer options
must have content
must be an integer
can return the value as an integer
returns nil if not in argv
array options
can return the value as an array
!
OptionWithContent
has a flag
is valid when it has no raw value
is valid when it has a value
can return it's value when present
returns nil if the flag has no raw value
Refactoring to Small Code 16x9 - April 24, 2014

124. Enable Labs @mark_menard
#smallcode
Now We’re Done!!
Let them implement their own
option classes. It’s easy.
Refactoring to Small Code 16x9 - April 24, 2014

125. Enable Labs @mark_menard
#smallcode
http://www.enablelabs.com/
info@enablelabs.com
866-895-8189
@mark_menard
Mark Menard Enable Labs
GitHub: MarkMenard
Refactoring to Small Code 16x9 - April 24, 2014

126. Enable Labs @mark_menard
#smallcode
Credits
• Syntax highlighting: pbpaste | highlight --syntax=rb --style=edit-xcode --out-format=rtf | pbcopy!
• Command line option example inspiration Uncle Bob.
Refactoring to Small Code 16x9 - April 24, 2014