Showing that a sub-class need not have an #initialize method

simpleinheritance.rb

class Person
  attr_reader :firstname, :lastname
  def initialize( first, last )
    @firstname, @lastname = first, last
  end
  def say_hi
    puts "Hello, my name is #{@firstname} #{@lastname}"
  end
end

class Child < Person
  def say_hi
    puts "HI I'M #{@firstname.upcase} I LIKE TURTLES"
  end
end

dad = Person.new "Robert", "Johnson"
kid = Child.new "Emily", "Johnson"

dad.say_hi #=> Hello, my name is Robert Johnson
kid.say_hi #=> HI I'M EMILY I LIKE TURTLES

simpleinheritance2.rb

class Person
  attr_reader :firstname, :lastname
  def initialize( first, last )
    @firstname, @lastname = first, last
  end
  def say_hi
    puts "Hello, my name is #{@firstname} #{@lastname}"
  end
end

class Child < Person
  def initialize( firsty, lasty, likey )
    super(firsty,lasty)
    @like = likey
  end
  def say_hi
    puts "HI I'M #{@firstname.upcase} I LIKE #{likey.upcase}"
  end
end

dad = Person.new "Robert", "Johnson"
kid = Child.new "Emily", "Johnson", "hot dogs"

dad.say_hi #=> Hello, my name is Robert Johnson
kid.say_hi #=> HI I'M EMILY I LIKE HOT DOGS