Code Review

class Dino
  attr_reader :name, :era, :size

  def initialize(name, era, size)
    @name = name
    @era = era
    @size = size
  end
end


    def filter(options = [])
      options.inject($DINOS) do |remaining, option|
        remaining.select { |dino|
          dino.send(option[0]).send(option[2] || :==, option[1])
        }
      end
    end

def main
  $DINOS = [
    Dino.new("Stegosaur", :jurassic, 500),
    Dino.new("T-rex", :cretaceous, 1000),
    Dino.new("Apatosaur", :cretaceous, 700)
  ]

  # Output shortened

  test_zero = filter()
  p "Test zero" + test_zero.inspect # Stegosaur, T-Rex, Apatosaur

  test_one = filter( [ [:size, 750, :< ] ] )
  p "Test one (size < 750): " + test_one.inspect # Stegosaur, Apatosaur

  test_two = filter( [ [:era, :cretaceous]])
  p "Test two (era = cretaceous): " + test_two.inspect # T-rex, Apatosaur

  test_three = filter( [[:era, :cretaceous], [:size, 800, :<]])
  p "Test three (era = cretaceous & size < 550): " + test_three.inspect # Apatosaur

end

main