one.plus.two.plus.one.minus.two.equals.ruby

class Base
  attr_reader :value

  def initialize(value)
    @value = value
  end
end

class Number < Base
  def plus
    Plus.new @value
  end

  def minus
    Minus.new @value
  end

  def equals
    @value
  end
end

class BaseOperator < Base
  def one
    operation(1)
  end

  def two
    operation(2)
  end
end

class Minus < BaseOperator
  def operation(number)
    Number.new(@value - number)
  end
end

class Plus < BaseOperator
  def operation(number)
    Number.new(@value + number)
  end
end


one = Number.new 1

puts one.plus.two.plus.one.minus.two.equals # 2