jsut simpel example for POO

circle.rb

class Cirle < Form
  attr_reader :rayon
  
  def initializer(rayon)
    @rayon = rayon
  end
  
  #Circle.area(20) => 200
  def self.area(rayon)
    Math.Pi * rayon**2
  end
  
  #Cicle.pring_area(20) => "Ma super surface est de: 200"
  def self.pring_area(rayon)
    puts "Ma super surface est de: #{self.area(rayon)}"
  end
  
  #Cicle.pring_area_with_instance(20) => "Ma super surface est de: 200"
  def self.pring_area_with_instance(rayon)
    mon_cirle = Circle.new(20)
    puts "Ma super surface est de: #{mon_cirle.area}"
  end
  
  #mon_cercle = Circle.new(20); mon_cercle.rayon => 20; mon_cercle.area => 200
  def area
    Circle.area(self.reayon)
  end
  
  #mon_volume = Circle.new(20); mon_cercle.rayon => 20; mon_cercle.area => 200; mon_cercle.volume => 4000
  def volume
    4/3 * self.area * self.rayon
  end
end

form.rb

class Form
  def color
  end
  
  def area
  end
  
  def volume
  end
end

square.rb

class Square < Forme
  
  def self.area(length)
  end
  
  def area
  end
  
  def volume
  end
end