player_02.rb

# -*- coding: utf-8 -*-
module Movable
  attr_reader :position

  def set_position(position)
    @position = position.is_a?(Movable) ? position.position : position
  end
  
  def set_ratio(x, y)
    @x_ratio = x
    @y_ratio = y
  end

  def move(direction)
    case direction
    when :up
      @position[:y] -= 10 * @y_ratio
    when :down
      @position[:y] += 10 * @y_ratio
    when :left
      @position[:x] -= 10 * @x_ratio
    when :right
      @position[:x] += 10 * @x_ratio
    end
  end
end

class NormalPlayer
  include Movable
  def initialize(position)
    set_position position
    set_ratio 1, 1
  end
end

class FastPlayer
  include Movable
  def initialize(position)
    set_position position
    set_ratio 2, 2
  end
end

class KaniPlayer
  include Movable
  def initialize(position)
    set_position position
    set_ratio 4, 0.5
  end
end

player = NormalPlayer.new :x => 100, :y => 100
player.move :up
p player.position # => {:x => 100, :y => 90}

player = FastPlayer.new player
player.move :down
p player.position #=> {:x => 100, :y => 110}

player = KaniPlayer.new player
player.move :up
player.move :left
p player.position #=> {:x => 60, :y => 105}

こんどこそModuleを使ってみた。抽象クラスっぽい感じ？
委譲より多重継承だよね。なんちゃって