The Art of Ruby: The spiritual successor to the Origamist's Ruby Learn how to write beautiful code and how programming is a form of art.

1. Matthew Mongeau
halogenandtoast
goose@thoughtbot.com

3. The Art of Ruby

4. A programmer who subconsciously
views himself as an artist will enjoy
what he does and will do it better.
Donald Knuth

5. What is Art?

6. /ärt/
the expression or application of
human creative skill and
imagination, typically in a visual
form such as painting or
sculpture, producing works to be
appreciated primarily for their
beauty or emotional power.

7. /ärt/
the expression or application of
human creative skill and
imagination, typically in a visual
form such as painting or
sculpture, producing works to be
appreciated primarily for their
beauty or emotional power.

8. What is Art

9. What is Art
It’s beautiful.

10. What is Art
It’s beautiful.
It’s creative.

11. What is Art
It’s beautiful.
It’s creative.
It’s expressive.

12. What is Programming

13. The art of
writing code.

14. Code is Art

15. Code is Art
It’s beautiful.

16. Code is Art
It’s beautiful.
It’s creative.

17. Code is Art
It’s beautiful.
It’s creative.
It’s expressive.

18. Writing beautiful Code

19. Simplicity

20. Code should be clear

21. def play
puts "Welcome to the guessing game."
3.times do
guess = get_guess
if won? guess
@won = true
puts "You win!"
break
else
puts "Wrong!"
end
end
if !@won
puts "You lost. The actual number is #{@actual_number}."
end
end

22. def play
puts "Welcome to the guessing game."
3.times do
guess = get_guess
if won? guess
@won = true
puts "You win!"
break
else
puts "Wrong!"
end
end
if !@won
puts "You lost. The actual number is #{@actual_number}."
end
end

23. Extract
Method
Pattern
def play
puts "Welcome to the guessing game."
play_rounds
print_results
end

24. Single Level
of Abstraction
Principle
def play
print_header
play_rounds
print_results
end

25. Complexity

26. Balance

27. def play_rounds
round_count.times do
if correct_guess? get_guess
@won = true
break
else
puts "Wrong!"
end
end
end

28. def play_rounds
@won = round_count.times.detect { play_round }
end
def play_round
if correct_guess? get_guess
true
else
puts "Wrong!"
end
end

29. def play_rounds
@won = round_count.times.detect { play_round }
end
def play_round
if correct_guess? get_guess
true
else
puts "Wrong!" # this returns nil which is falsey
end
end

30. Constraints

31. The more constraints one imposes,
the more one frees one's self.
Igor Stravinsky

32. Code Constraints

33. Code Constraints
5 line methods

34. Code Constraints
5 line methods
100 line classes

35. Code Constraints
5 line methods
100 line classes
No classes in public methods

36. def play
puts "Welcome to the guessing game."
3.times do
guess = get_guess
if won? guess
@won = true
puts "You win!"
break
else
puts "Wrong!"
end
end
if !@won
puts "You lost. The actual number is #{@actual_number}."
end
end

37. def play
print_header
play_rounds
print_results
end

38. def play_rounds
round_count.times do
if correct_guess? get_guess
@won = true
break
else
puts "Wrong!"
end
end
end

39. def play_rounds
@won = round_count.times.detect { play_round }
end
def play_round
if correct_guess? get_guess
true
else
puts "Wrong!"
end
end

40. def play_rounds
@won = round_count.times.detect { play_round }
end
def play_round
if correct_guess? get_guess
true
else
puts "Wrong!" # this is still bothering me
end
end

41. Breaking the Rules

42. Pablo
Learn the rules like a
pro, so you can break
them like an artist.
Picasso

43. def play_round
if correct_guess? get_guess
true
else
puts "Wrong!"
end
end

44. def play_round
if correct_guess? get_guess
puts "Correct"
true
else
puts "Wrong!"
false
end
end

45. def play_round
if correct_guess? get_guess
correct_guess
else
incorrect_guess
end
end
def incorrect_guess
puts "Wrong!"
false
end
def correct_guess
puts "Correct"
false
end

46. def play_round
if correct_guess? get_guess
correct_guess
else
incorrect_guess
end
end
def incorrect_guess
puts "Wrong!"
false
end
def correct_guess
puts "Correct"
false
end

47. class Guess
def initialize actual_number
@actual_number = actual_number
@guess = get_guess
end
Extract
Class
Pattern
def status
if correct?
"Correct"
else
"Incorrect"
end
end
def correct?
guess == actual_number
end
private
attr_reader :guess, :actual_number
def get_guess
print "What is your guess: "
gets.to_i
end
end

48. Extract
Class
Pattern
def play_round
guess = Guess.new(actual_number)
puts guess.display_status
guess.correct?
end

49. 1
Extract Method

50. 1 2
Extract Method
Extract Class

51. 1 2 3
Extract Method
Extract Class
Extract Gem
or App

52. You Win

53. Performance

54. If you’re willing to restrict the
flexibility of your approach, you can
almost always do something better.
John Carmack

58. module Alchemist
module Conversion
def method_missing unit_name, *args, &block
exponent, unit_name = Alchemist.parse_prefix(unit_name)
if Alchemist.has_measurement?(unit_name)
Alchemist.measurement self, unit_name, exponent
else
super( unit_name, *args, &block )
end
end
end
end
class Numeric
include Alchemist::Conversion
end

59. module Alchemist
module Conversion
def method_missing unit_name, *args, &block
exponent, unit_name = Alchemist.parse_prefix(unit_name)
if Alchemist.has_measurement?(unit_name)
Alchemist.measurement self, unit_name, exponent
else
super( unit_name, *args, &block )
end
end
end
end
class Numeric
include Alchemist::Conversion
end

60. def self.parse_prefix(unit)
matches = unit.to_s.match(prefix_matcher)
prefix, parsed_unit = matches.captures
if prefix && si_units.include?(parsed_unit)
value = prefixed_value_for(prefix.to_sym, parsed_unit)
[value, parsed_unit.to_sym]
else
[1, unit]
end
end

61. def self.parse_prefix(unit)
matches = unit.to_s.match(prefix_matcher)
prefix, parsed_unit = matches.captures
if prefix && si_units.include?(parsed_unit)
value = prefixed_value_for(prefix.to_sym, parsed_unit)
[value, parsed_unit.to_sym]
else
[1, unit]
end
end

62. def self.parse_prefix(unit)
matches = unit.to_s.match(prefix_matcher)
prefix, parsed_unit = matches.captures
if prefix && si_units.include?(parsed_unit)
value = prefixed_value_for(prefix.to_sym, parsed_unit)
[value, parsed_unit.to_sym]
else
[1, unit]
end
end

63. def self.prefix_matcher
keys = unit_prefixes.keys.map(&:to_s).
sort{ |a,b| b.length <=> a.length }
%r{^(#{keys.join('|')})?(.+)}
end

64. [:googol, :yotta, :Y, :zetta, :Z,
:exa, :E, :peta, :P, :tera, :T,
:giga, :G, :mega, :M, :kilo, :k,
:hecto, :h, :deca, :da, :deci, :d,
:centi, :c, :milli, :m, :micro, :u,
:nano, :n, :pico, :p, :femto, :f,
:atto, :a, :zepto, :z, :yocto, :y,
:kibi, :Ki, :mebi, :Mi, :gibi, :Gi,
:tebi, :Ti, :pebi, :Pi, :exbi, :Ei,
:zebi, :Zi, :yobi, :Yi]

65. /^(googol|yotta|femto|zetta|zepto|micro|
milli|centi|hecto|yocto|exbi|giga|tebi|
mega|pebi|kilo|atto|tera|kibi|deca|yobi|
deci|pico|nano|gibi|zebi|mebi|peta|exa|Ki|
Mi|Gi|Zi|da|Ei|Ti|Pi|Yi|z|a|y|f|p|n|m|c|d|
h|k|M|G|T|P|E|Z|Y|u)?(.+)/

66. Some people, when confronted
with a problem, think "I know, I'll
use regular expressions." Now
they have two problems.
Jamie Zawinski

67. I thought
"I know, I'll use regular expressions."

68. I now had two problems

69. but

70. def self.prefix_matcher
@prefix_matcher ||= begin
prefix_keys = unit_prefixes.keys.map(&:to_s).
sort{ |a,b| b.length <=> a.length }
%r{^(#{prefix_keys.join('|')})?(.+)}
end
end

72. 2.0

73. 1.9

74. Constraints
Keep existing interface

75. Constraints
Keep existing interface
No method_missing

76. Constraints
Keep existing interface
No method_missing
Increase performance

77. module Alchemist
def self.setup category = nil
if category
load_category category
else
load_all_categories
end
end
private
def self.load_all_categories
library.load_all_categories
end
def self.load_category category
library.load_category category
end
end

78. module Alchemist
class ModuleBuilder
def initialize category
@category = category
end
def build
Module.new.tap do |category_module|
category_module.class_eval %(def self.inspect()
"#<Module(#{category})>" end)
category_module.class_eval category_methods
end
end

79. private
attr_reader :category
def library
Alchemist.library
end
def category_methods
unit_names.map do |name|
%(define_method("#{name}") { Alchemist.measure self, :#{name} }) +
"n" + prefixed_methods(name)
end.join("n")
end
def unit_names
library.unit_names(category)
end
def prefixes_with_value(name)
if library.si_units.include?(name.to_s)
library.unit_prefixes
else
[]
end
end
def prefixed_methods(name)
prefixes_with_value(name).map do |prefix, value|
%(define_method("#{prefix}#{name}") { Alchemist.measure self, :#{name}, #{value} })
end.join("n")
end

80. module Alchemist
class ModuleBuilder
def initialize category
@category = category
end
def build
Module.new.tap do |category_module|
category_module.class_eval %(def self.inspect()
"#<Module(#{category})>" end)
category_module.class_eval category_methods
end
end

81. module Alchemist
class ModuleBuilder
def initialize category
@category = category
end
def build
build_module do |category_module|
define_inspect_method(category_module)
define_unit_methods(category_module)
end
end

83. [success_kid.jpg]

84. #include <ruby.h>
#include <string.h>
the c-level
VALUE cParenParser;
VALUE paren_parser_parse(VALUE self, VALUE str) {
const char *c_str = RSTRING_PTR(str);
char *temp = (char *)malloc(sizeof(char) * RSTRING_LEN(str) + 1);
int temp_pos = 1;
int c_str_pos = 0;
temp[0] = c_str[0];
while(c_str[c_str_pos++] != '0') {
if(temp_pos > 0 && temp[temp_pos-1] == ')' && c_str[c_str_pos] == '(') {
temp_pos--;
} else {
temp[temp_pos++] = c_str[c_str_pos];

85. How to be an artist

86. Have a toolbox

87. Be inspired by others

88. Surround yourself with
talented artists

89. Surround yourself with
talented artists

90. Use well known
techniques

91. Use well known
techniques

92. Measure improvement

95. PULLREVIEW

97. Have feelings

98. Know when to break
the rules

99. Have fun.

100. Prime
learn.thoughtbot.com/prime

101. THISISMETIS.COM

102. ?