Pipeline in Ruby

filter.rb

class Filter
  class << self
    def filters
      @filters ||= {}
    end

    def add(name, &code)
      filters[name] = code
    end
  end

  def initialize(obj)
    @methods = []
    @obj = obj
  end

  def |(method)
    @methods << method
    self
  end

  def run
    @methods.inject(@obj) do |mem, method|
      if custom = Filter.filters[method]
        custom.call(mem)
      else
        mem.send method
      end
    end
  end

  def to_s
    run.to_s
  end
end

module CoreExt
  [Fixnum, Float, String].each do |klass|
    refine klass do
      def |(other)
        return super unless other.is_a?(Symbol)
        Filter.new(self) | other
      end
    end
  end
end