A simple rakefile to run livereload and generate css from the sass (scss) files specified in asset_packages.yml.

livereload.rake

desc "Continuously watch for changes and rebuild files"
task :livereload do
  pids = `ps ax|grep ruby|grep livereload|awk '{ print $1 }'`.split
  other_pids = pids.reject { |pid| Process.pid == pid.to_i }
  system "kill #{other_pids.join(' ')} &> /dev/null"
  system "nohup livereload &> /dev/null &"
  
  require 'rubygems'
  require 'fssm'

  def render_sass(file)
    sh 'vendor/gems/haml-3.0.4/bin/sass', file, 
       "public/stylesheets/generated/#{file.to_s.split("sass/").last.gsub(/scss/, 'css')}"
  end
  
  def find_main_file(updated_file)    
    if @main_sass_files.find { |file| file == updated_file }
      [ updated_file ]
    else
      # TODO: find deps for partials
      @main_sass_files
    end
  end

  def render_sass_files(updated_file = nil)
    @assets ||= YAML.load_file("#{Rails.root}/config/asset_packages.yml")
    @main_sass_files ||= @assets["stylesheets"].map { |group| group.values }.flatten.
                              find_all { |file| file.include?('generated') }.
                              map { |file|
                                 "public/stylesheets/#{file}.scss".
                                 gsub(/generated/, 'sass') }

    files = updated_file ? find_main_file(updated_file) : @main_sass_files
    files.each { |file| render_sass(file) }
  end

  begin
    FSSM.monitor(nil, ['**/*.scss']) do
      update { |base, rel| render_sass_files(rel) }
      delete { render_sass_files }
      create { render_sass_files }
    end
  rescue FSSM::CallbackError => e
    puts e.inspect
    Process.exit
  end
 
end