hamamatsu.rb#3 protectedなインスタンス変数getterを利用した比較

compare_sample.rb

class Foo
  include Comparable

  def initialize(x, y)
    @x = x
    @y = y
  end
  
  def <=>(rhs)
    return nil unless rhs.instance_of? Foo
    if @x == rhs.x
      @y <=> rhs.y
    else 
      @x <=> rhs.x
    end
  end

  protected
  attr_reader :x, :y
end 

# a  = Foo.new(2, 3)
# aa = Foo.new(2, 3)
# b  = Foo.new(4, 5)
# 
# puts a == aa    #=> true
# puts a == b     #=> false
# puts a < aa     #=> false
# puts a < b      #=>  true