module Comma class Extractor def initialize(instance, &block) @instance = instance @block = block @results = [] end def results instance_eval &@block @results end end class HeaderExtractor < Extractor def method_missing(sym, *args, &block) @results << sym.to_s.humanize if args.blank? args.each do |arg| case arg when Hash arg.each do |k, v| @results << ((v.is_a? String) ? v : v.to_s.humanize) end when Symbol @results << arg.to_s.humanize when String @results << arg when Array else raise "Unknown header symbol #{arg.inspect}" end end end end class DataExtractor < Extractor def method_missing(sym, *args, &block) @results << @instance.send(sym).to_s if args.blank? method_arguments = args.detect{ |arg| arg.is_a? Array } || [] args.each do |arg| case arg when Hash arg.each do |k, v| @results << @instance.send(sym, *method_arguments).send(k).to_s end when Symbol @results << @instance.send(sym, *method_arguments).send(arg).to_s when String @results << @instance.send(sym, *method_arguments).to_s when Array else raise "Unknown data symbol #{arg.inspect}" end end end end end