gistfile1.rb

class Dog
  attr_accessor :animal_type
  %w(cats dogs rabbits pigs cows).each do |t|
    define_method "has_#{t}" do |number|
      @animal_type = t
      puts number
    end
  end
end

d = Dog.new
d.has_dogs 10
puts d.animal_type
p d.methods.sort

gistfile2.rb

class Dog
  attr_accessor :number_of_computers
  def method_missing(name, *args)
    name = name.to_s
    name =~ /has_(\d+)_computers/
    @number_of_computers = $1.to_i
  end
end

d = Dog.new
d.has_20_computers
puts d.number_of_computers