ChainQuery allow you to build query by method chains.

chain_query.rb

class ChainQuery
  def initialize(init_value)
    @init_value =  init_value
    @filters =  []
  end

  def add_filter(&block)
    @filters <<  block
    self
  end

  def value
    @filters.reduce(@init_value) {|last_value, filter| filter.call(last_value) }
  end
end

class Calculator < ChainQuery
  def add_1
    add_filter {|val| val + 1}
  end

  def sub_1
    add_filter {|val| val - 1}
  end
end

Calculator.new(0).add_1.add_1.sub_1.value #=> 1
Calculator.new(10).sub_1.add_1.sub_1.value #=> 9