module ActiveSupport # This class is responsible to track files and invoke the given block # whenever one of these files are changed. For example, this class # is used by Rails to reload the I18n framework whenever they are # changed upon a new request. # # i18n_reloader = ActiveSupport::FileUpdateChecker.new(paths) do # I18n.reload! # end # # ActionDispatch::Reloader.to_prepare do # i18n_reloader.execute_if_updated # end # class FileUpdateChecker attr_reader :paths, :last_update_at def initialize(paths, calculate=false, &block) @paths = paths @block = block @last_update_at = calculate ? updated_at : nil end def updated_at paths.map { |path| File.mtime(path) }.max end def execute_if_updated current_update_at = self.updated_at if @last_update_at != current_update_at @last_update_at = current_update_at @block.call end end end end