指定したメンバがすべて同値の場合に == が true を返す attr_reader みたいな

iffattrs.rb

class Class

  def iffattrs *attrs
    define_method(:==) do |other|
      attrs.each do |attr|
        symbol = :"@#{attr}"
        return false if instance_variable_get(symbol) != other.instance_variable_get(symbol)
      end
      true
    end
  end

end

if __FILE__ == $PROGRAM_NAME

  require "test/unit"

  class SampleClass

    def initialize name, age
      @name = name
      @age = age
    end

    iffattrs :name, :age

  end

  class TestIffattrs < Test::Unit::TestCase

    def test_iffattrs

      assert_equal SampleClass.new("Yae", 16), SampleClass.new("Yae", 16)

    end

  end

end