Ruby

First Step

Call Ruby command line

irb

Methode

• Define a methode "m"

def m(name = "World")
puts "Hello Mr #{name.capitalize}!"
end

• Execute

m("nicolas")

Hello Mr Nicolas!
=> nil

Class

class Greeter
  def initialize(name = "World")
   @name = name
  end
  def say_hi
    puts "Hi #{@name}!"
  end
  def say_bye
    puts "Bye #{@name}, come back soon."
   end
end

• class define a new class
• @name is a variable d'instance

Object

irb>o = Greeter.new("Nicolas")
=> #<Greeter:0x00000002579a48 @name="Nicolas">

irb>o.say_hi
Hi Nicolas!
=> nil

irb> o.say_bye
Bye Nicolas, come back soon.
=> nil

Methodes of a particular Object

• Current Object and parent

irb>Greeter.instance_methods
=> [:say_hi, :say_bye, :m, :nil?, :===, :=~, :!~, :eql?, :hash, :<=>, :class, :singleton_class, :clone, :dup, :initialize_dup, :initialize_clone, :taint, :tainted?, :untaint, :untrust, :untrusted?, :trust, :freeze, :frozen?, :to_s, :inspect, :methods, :singleton_methods, :protected_methods, :private_methods, :public_methods, :instance_variables, :instance_variable_get, :instance_variable_set, :instance_variable_defined?, :instance_of?, :kind_of?, :is_a?, :tap, :send, :public_send, :respond_to?, :respond_to_missing?, :extend, :display, :method, :public_method, :define_singleton_method, :object_id, :to_enum, :enum_for, :==, :equal?, :!, :!=, :instance_eval, :instance_exec, :__send__, :__id__]

• Current Object only

irb>Greeter.instance_methods(false)
=> [:say_hi, :say_bye]

Validate Object Methode

irb>o.respond_to?("name")
=> false

o.respond_to?("say_hi")
=> true

o.respond_to?("to_s")
=> true

Change Class Attribut

irb>class Greeter
attr_accessor :name
end

o = Greeter.new("MySelf")

o.respond_to?("name")

o.respond_to?("name=")

o.say_hi

o.name="Betty"

o

o.name

o.say_hi

• attr_accessor add tow methods "name" and ""name=""

Create a batch file

#!/usr/bin/env ruby

class MegaGreeter
  attr_accessor :names

  # Création d'un objet
  def initialize(names = "World")
    @names = names
  end

  # Saluer tout le monde
  def say_hi
    if @names.nil?
      puts "..."
    elsif @names.respond_to?("each")
      # @names est une liste de noms : traitons-les uns par uns
      @names.each do |name|
        puts "Hello #{name}!"
      end
    else
      puts "Hello #{@names}!"
    end
  end

  # Dire au revoir à tout le monde
  def say_bye
    if @names.nil?
      puts "..."
    elsif @names.respond_to?("join")
      # Grouper les différents noms de la liste par des virgules
      puts "Goodbye #{@names.join(", ")}.  Come back soon!"
    else
      puts "Goodbye #{@names}.  Come back soon!"
    end
  end

end


if __FILE__ == $0
  mg = MegaGreeter.new
  mg.say_hi
  mg.say_bye

  # Modifier le nom en Zeke
  mg.names = "Zeke"
  mg.say_hi
  mg.say_bye

  # Changer le nom pour un tableau (une liste de noms)
  mg.names = ["Albert", "Brenda", "Charles",
    "Dave", "Engelbert"]
  mg.say_hi
  mg.say_bye

  # Maintenant, le nom n'est plus...
  mg.names = nil
  mg.say_hi
  mg.say_bye
end

>ruby helloworl.rb

Structure

If

# If null
  if @names.nil?
    puts "..."
  elsif @names.respond_to?("join")
    # Grouper les noms par des virgules
    puts "Goodbye #{@names.join(", ")}.  Come back soon!"
  else
    puts "Goodbye #{@names}.  Come back soon!"
  end

Iteration

@names.each do |name|
  puts "Hello #{name}!"
end