class Middleman::CoreExtensions::Data

def start_watching(dir)
  @original_data_dir = dir
  # Tell the file watcher to observe the :data_dir
  @watcher = app.files.watch :data,
                             path: File.join(app.root, dir),
                             ignore: proc { |f| !DATA_FILE_MATCHER.match(f[:relative_path]) }
  # Setup data files before anything else so they are available when
  # parsing config.rb
  app.files.on_change(:data, &@data_store.method(:update_files))
end