gistfile1.rb

module Nanoc3::Filters
  class Tar < Nanoc3::Filter

    type :text => :binary
    identifier :tar

    def run(filename, params={})
      # Stores the filenames of all reps to include
      filenames = []

      # For each item to include (as identifier)
      @item[:identifiers].each do |identifier|
        # Find the default representation (you could pick another one too)
        rep = @items.find { |i| i.identifier == identifier }.rep_named(:default)

        # Notify to create a dependency
        Nanoc3::NotificationCenter.post(:visit_started, rep.item)
        Nanoc3::NotificationCenter.post(:visit_ended,   rep.item)

        # Raise unmet dependency error if item is not yet compiled
        raise Nanoc3::Errors::UnmetDependency.new(rep) if !rep.compiled?

        # Add it to list of files to tar
        filenames << rep.raw_path
      end

      # Tar
      system('tar', '-c', '-j', '-f', output_filename, *filenames)
    end

  end
end