Spiral with logo DSL

gistfile1.rb

class Turtle
  DIRECTIONS = [:UP, :RIGHT, :DOWN, :LEFT]

  def initialize(size)
    @size = size
    @array = Array.new(size)
    @array.map! {|line| line = Array.new(size, " ")}
    @direction = :RIGHT
    @x = 0
    @y = 0
    @array[@y][@x] = "*"
  end

  def walk(step_numbers)
    step_numbers.times do
      case @direction
        when :UP
          @y = @y - 1 if @y > 0
        when :DOWN
          @y = @y + 1 if @y < @size
        when :LEFT
          @x = @x - 1 if @x > 0
        when :RIGHT
          @x = @x + 1 if @x < @size
      end
      @array[@y][@x] = "*"
    end
  end

  def print()
    @array.each {|line| puts(line.join(''))}
  end

  def turn()
    @direction = DIRECTIONS[(DIRECTIONS.index(@direction) + 1) % 4]
  end

end

size = 16

t = Turtle.new(size)

size.downto(0) do |step|
  t.walk(step)
  t.turn
end

t.print()