shows very simplified version of how I implemented my itinerary

itinerary.rb

module Itinerary
  
  class Day
    def initialize(date,&block)
      @date = date
      instance_eval(&block)
    end
    def readings
      @readings ||= Array.new
    end
    def read(title)
      readings << Read.new(title)
    end
    def to_s
      @date
    end
  end
  
  class Read
    def initialize(title)
      @title = title
    end
    def to_s
      @title
    end
  end
  
  module Output
    def self.output(days)
      days.map do |day|
        [ day , 
          day.readings.map { |reading| "  #{reading}" }
        ]
      end.flatten.join("\n")
    end
  end
  
  def self.output
    Output.output days
  end
  
  def self.by(date,&block)
    days << Day.new( date , &block )
  end
  
  def self.days
    @days ||= Array.new
  end
    
end

def by(date,&block)
  Itinerary.by(date,&block)
end


by 'Monday' do
  read 'page 1'
  read 'page 2'
end

by 'Tuesday' do
  read 'page 3'
  read 'page 4'
end

puts Itinerary.output


# >> Monday
# >>   page 1
# >>   page 2
# >> Tuesday
# >>   page 3
# >>   page 4