Ruby introduction for newbies

Transcript

1. RUBY Hemant & Sidu Saturday 16 June 12

2. RUBY LANGUAGE Ruby is a object oriented programming language deeply

   inspired by Smalltalk, Lisp & Perl. It is also a dynamic but strongly typed language. Saturday 16 June 12

3. ABOUT DYNAMIC LANGUAGES Dynamically Typed. Dynamic Language. Saturday 16 June

   12

4. STRONGLY TYPED Javascript 1 + "Hello" => "1Hello" Ruby 1

   + "Hello" => TypeError class Fixnum def +(other); "#{self}#{other}"; end end Saturday 16 June 12

5. Javascript collect_milk([cow, hen,python]) Ruby collect_milk([cow, hen,python]) Saturday 16 June 12

6. CLASSES & OBJECTS Everything in Ruby is a object methods

   classes lambdas integers Saturday 16 June 12

7. CLASSES class Car def initialize @name = "Ferrari" end def

   say_name puts @name end end ferrari = Car.new() ferrari.say_name Saturday 16 June 12

8. CLASSES class Car def initialize @name = "Ferrari" end def

   say_name puts @name end end ferrari = Car.new() ferrari.say_name Output: Ferrari Saturday 16 June 12

9. MODULES A Module is a collection of methods and constants.

   Instance methods appear as methods in a class when the module is included. Saturday 16 June 12

10. MODULES module AnimalBehaviour def eat puts "Eating now" end end

    class Dog include AnimalBehaviour end tommy = Dog.new() tommy.eat() Saturday 16 June 12

11. MODULES module AnimalBehaviour def eat puts "Eating now" end end

    class Dog include AnimalBehaviour end tommy = Dog.new() tommy.eat() Output : Eating now Saturday 16 June 12

12. CLASS HIERARCHY Saturday 16 June 12

13. Saturday 16 June 12

14. class Car def initialize @name = "Ferrari" end end Saturday

    16 June 12

15. Car class Car def initialize @name = "Ferrari" end end

    Saturday 16 June 12

16. Car Object class Car def initialize @name = "Ferrari" end

    end Saturday 16 June 12

17. Car Object class Car def initialize @name = "Ferrari" end

    end Saturday 16 June 12

18. Car Object BasicObject class Car def initialize @name = "Ferrari"

    end end Saturday 16 June 12

19. Car Object BasicObject class Car def initialize @name = "Ferrari"

    end end Saturday 16 June 12

20. Car Object BasicObject ferrari = Car.new class Car def initialize

    @name = "Ferrari" end end Saturday 16 June 12

21. Car Object BasicObject ferrari = Car.new class Car def initialize

    @name = "Ferrari" end end Saturday 16 June 12

22. Class Car Object BasicObject ferrari = Car.new class Car def

    initialize @name = "Ferrari" end end Saturday 16 June 12

23. Class Car Object BasicObject ferrari = Car.new class Car def

    initialize @name = "Ferrari" end end Saturday 16 June 12

24. Class Module Car Object BasicObject ferrari = Car.new class Car

    def initialize @name = "Ferrari" end end Saturday 16 June 12

25. Class Module Car Object BasicObject ferrari = Car.new class Car

    def initialize @name = "Ferrari" end end Saturday 16 June 12

26. Class Module Object Car Object BasicObject ferrari = Car.new class

    Car def initialize @name = "Ferrari" end end Saturday 16 June 12

27. Class Module Object Car Object BasicObject ferrari = Car.new class

    Car def initialize @name = "Ferrari" end end Saturday 16 June 12

28. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new

    class Car def initialize @name = "Ferrari" end end Saturday 16 June 12

29. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new

    class Car def initialize @name = "Ferrari" end end Saturday 16 June 12

30. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new

    class Car def initialize @name = "Ferrari" end end Saturday 16 June 12

31. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new

    class Car def initialize @name = "Ferrari" end end Saturday 16 June 12

32. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new

    class Car def initialize @name = "Ferrari" end end Saturday 16 June 12

33. RECAP Saturday 16 June 12

34. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Saturday 16 June 12

35. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Class Saturday 16 June 12

36. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Class Module Saturday 16 June 12

37. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Class Module Object Saturday 16 June 12

38. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12

39. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12

40. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12

41. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12

42. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12

43. RECAP module AnimalBehaviour def eat puts "Eating now" end end

    class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12

44. OBJECT VS BASICOBJECT class Object < BasicObject include Kernel end

    Saturday 16 June 12

45. VARIABLES module GameWorld class Planet def initialize(name) @name = name

    end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def position @position end end end alien = GameWorld::Alien.make_alien() Saturday 16 June 12

46. module GameWorld class Planet def initialize(name) @name = name end

    def name @name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def position @position end end end alien = GameWorld::Alien.make_alien() Saturday 16 June 12

47. module GameWorld class Planet def initialize(name) @name = name end

    def name @name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def position @position end end end alien = GameWorld::Alien.make_alien() earth = Planet.new("Earth") earth.name Saturday 16 June 12

48. module GameWorld class Planet def initialize(name) @name = name end

    def name @name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def position @position end end end alien = GameWorld::Alien.make_alien() earth = Planet.new("Earth") earth.name Output : Earth Saturday 16 June 12

49. module GameWorld class Planet def initialize(name) @name = name end

    end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.alien_count @alien_count end def position @position end end end alien = GameWorld::Alien.make_alien() Saturday 16 June 12

50. module GameWorld class Planet def initialize(name) @name = name end

    end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.alien_count @alien_count end def position @position end end end alien = GameWorld::Alien.make_alien() Alien.alien_count Saturday 16 June 12

51. module GameWorld class Planet def initialize(name) @name = name end

    end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.alien_count @alien_count end def position @position end end end alien = GameWorld::Alien.make_alien() Alien.alien_count Output : 1 Saturday 16 June 12

52. module GameWorld class Planet def initialize(name) @name = name end

    end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.planet @@planet end def position @position end end end alien = GameWorld::Alien.make_alien() Saturday 16 June 12

53. module GameWorld class Planet def initialize(name) @name = name end

    end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.planet @@planet end def position @position end end end alien = GameWorld::Alien.make_alien() Alien.planet Saturday 16 June 12

54. module GameWorld class Planet def initialize(name) @name = name end

    end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.planet @@planet end def position @position end end end alien = GameWorld::Alien.make_alien() Alien.planet Output : Planet(“Mars”) Saturday 16 June 12

55. http://www.ruby-doc.org/core-1.9.3/BasicObject.html Ruby 1.8 does not have BasicObject Metaclass Saturday 16

    June 12

56. DUCK TYPING Saturday 16 June 12

57. DUCK TYPING class Cow def milkit; end end class Goat

    def milkit; end end Saturday 16 June 12

58. DUCK TYPING def collect_milk(animal) if animal.respond_to?(:milkit) animal.milkit else raise InvalidArgument.new("Cant

    milk #{animal.inspect}") end end class Cow def milkit; end end class Goat def milkit; end end Saturday 16 June 12

59. Embrace Duck typing Saturday 16 June 12

60. def collect_milk(animal) if animal.is_a?(Cow) animal.milkit end end Saturday 16 June

    12

61. Saturday 16 June 12

62. def collect_milk(animal) if animal.respond_to?(:milkit) animal.milkit else raise InvalidArgument.new("Cant milk #{animal.inspect}")

    end end Saturday 16 June 12

63. EMBRACE POLYMORPHISM Saturday 16 June 12

64. def total_score(test) if test.is_a?(EnglishTest) test.subjective_score elsif test.is_a?(MathTest) test.total_marks end end

    Saturday 16 June 12

65. class EnglishTest def total_score end end class MathTest def total_score

    end end test.total_score Saturday 16 June 12

66. NAH I AM NOT THAT DUMB Saturday 16 June 12

67. HASH student_scores = { hemant: {math: 10, science: 20, total:

    30}, kiran: {math: 20, science: 30, total: 50}, sidu: {math: 20, science: 30, total: 50} } Saturday 16 June 12

68. USE BUT DON’T ABUSE HASH Saturday 16 June 12

69. def scrap_pirate_bay(response) scrap_output = {} scrap_output[:title] = response.title ? response.title

    : "Pirates Rule" scrap_output[:body] = response.body scrap_output end Saturday 16 June 12

70. Saturday 16 June 12

71. def scrap_pirate_bay(response) scrap_output = {} scrap_output[:title] = response.title ? response.title

    : "Pirates Rule" scrap_output[:body] = response.body scrap_output end Saturday 16 June 12

72. def scrap_pirate_bay(response) scrap_output = {} scrap_output[:title] = response.title ? response.title

    : "Pirates Rule" scrap_output[:body] = response.body scrap_output end Saturday 16 June 12

73. def scrap_pirate_bay(response) scrap_output = {} scrap_output[:title] = response.title ? response.title

    : "Pirates Rule" scrap_output[:body] = response.body scrap_output end Use a Class Saturday 16 June 12

74. OMFG performance and garbage collector What is wrong with hashes?

    Saturday 16 June 12

75. You Mad Bro? Saturday 16 June 12

76. KNOW THY DATA STRUCTURES fruits = ["apple","orange","apple"] fruits.uniq fruits =

    Set.new() fruits += ["apple","orange","apple"] Saturday 16 June 12

77. KNOW THY DATA STRUCTURES fruits = ["apple","orange","apple"] fruits.uniq fruits =

    Set.new() fruits += ["apple","orange","apple"] Output : [“apple”,”orange”] Saturday 16 June 12

78. DEFINE YOUR CLASSES INSIDE MODULES Saturday 16 June 12

79. module Leman class Ferrari end class Maruti800 end end Saturday

    16 June 12

80. IMO in Rails - DHH did a mistake by putting

    all the module, controller, helpers in global scope Saturday 16 June 12

81. Saturday 16 June 12

82. Saturday 16 June 12

83. LAMBDAS Saturday 16 June 12

84. I DON’T KNOW WHY THEY EVEN EXISTS! Saturday 16 June

    12

85. Saturday 16 June 12

86. I know why it exists and I am using them

    with ActiveRecord scopes. But can never think why will my own method need a lambda. Saturday 16 June 12

87. fortune_cookie = lambda { stocks = ['GROUPON','FACEBOOK','ZYNGA'] puts "You should

    invest in #{stocks[rand(3)]}" end fortune_cookie.call() Saturday 16 June 12

88. fortune_cookie = lambda { stocks = ['GROUPON','FACEBOOK','ZYNGA'] puts "You should

    invest in #{stocks[rand(3)]}" end fortune_cookie.call() You should invest in GROUPON Saturday 16 June 12

89. YOU CAN PASS THEM AS ARGUMENTS class MailParser def parse(filename,mailer)

    mail_object = do_some_hocus_pocus(filename) mailer.call(mail_object) ensure filename.close() end end mail_parser = MailParser.new() mail_parser.parse("foo.mail", lambda { |mail| mail.send() }) Saturday 16 June 12

90. AS ANONYMOUS FUNCTION Saturday 16 June 12

91. AS ANONYMOUS FUNCTION def shoot(target,gun, crouch_flag = false) return true

    if target.dead? loop { if gun.has_bullets? dead_yet = target.shoot(gun,crouch_flag) if dead_yet break end else gun.reload end } end Saturday 16 June 12

92. AS ANONYMOUS FUNCTION def shoot(target,gun, crouch_flag = false) shoot_algo =

    lambda do return false if gun.has_bullets? target.shoot(gun,crouch_flag) end return true if target.dead? loop { x = shoot_algo.call() x ? break : gun.reload } end def shoot(target,gun, crouch_flag = false) return true if target.dead? loop { if gun.has_bullets? dead_yet = target.shoot(gun,crouch_flag) if dead_yet break end else gun.reload end } end Saturday 16 June 12

93. BLOCKS & LAMBDAS Saturday 16 June 12

94. BROTHERS IN ARMS Saturday 16 June 12

95. class MailParser def parse(filename) mail_object = do_some_hocus_pocus(filename) yield mail_object ensure

    filename.close() end end mail_parser = MailParser.new() mail_parser.parse("foo.mail") {|mail| mail.send } Saturday 16 June 12

96. class MailParser def parse(filename) mail_object = do_some_hocus_pocus(filename) yield mail_object ensure

    filename.close() end end mail_parser = MailParser.new() mail_parser.parse("foo.mail") {|mail| mail.send } Saturday 16 June 12

97. http://eli.thegreenplace.net/2006/04/18/understanding-ruby- blocks-procs-and-methods/ Saturday 16 June 12

98. EAT THEM FOR BREAKFAST & LUNCH Saturday 16 June 12

99. META- PROGRAMMING Saturday 16 June 12

100. Saturday 16 June 12

101. 0 22.5 45 67.5 90 Newbie Can hold my ground

     Expert Guru Meta Programming Usage Saturday 16 June 12

102. 0 22.5 45 67.5 90 Newbie Can hold my ground

     Expert Guru Meta Programming Usage You know nothing John Snow Saturday 16 June 12

103. 0 22.5 45 67.5 90 No Understand Kinda Understand Public

     Enemy Guru Meta Programming Usage Saturday 16 June 12

104. 0 22.5 45 67.5 90 No Understand Kinda Understand Public

     Enemy Guru Meta Programming Usage You know nothing John Snow Saturday 16 June 12

105. http://pragprog.com/screencasts/v-dtrubyom/the-ruby-object- model-and-metaprogramming Saturday 16 June 12

106. ENGINEERING IS NOT OPTIONAL Saturday 16 June 12

107. DESIGN IS NOT JUST FOR DESIGNERS Saturday 16 June 12

108. OO IS NOT JUST FOR JAVA PROJECTS Saturday 16 June

     12

109. SE IS ABOUT PEOPLE Saturday 16 June 12

110. STUDY PEOPLE STUDY PRODUCTIVITY Saturday 16 June 12