My assetfile

require "json"
require "rake-pipeline-web-filters"

# this gives you concat, coffee_script, and minispade methods
require "rake-pipeline-web-filters/helpers"

class HandlebarsFilter < Rake::Pipeline::Filter
  def initialize(&block)
    block ||= proc { |input| input.sub(/\.handlebars$/, '.js') }
    super(&block)
  end

  def generate_output(inputs, output)
    inputs.each do |input|
      output.write "return Ember.Handlebars.compile(#{input.read.to_json})"
    end
  end
end

# process all js, css and html files in app/assets
input "assets"

# processed files should be outputted to public
output "public"

# process all coffee files
match "**/*.coffee" do
  # compile all CoffeeScript files. the output file
  # for the compilation should be the input name
  # with the .coffee extension replaced with .js
  coffee_script

  # The coffee_script helper is exactly equivalent to:
  # filter Rake::Pipeline::Web::Filters::CoffeeScriptCompiler
end

match "**/*.js" do
  minispade
  if ENV['RAKEP_ENV'] == "production"
    concat "application.js"
  else
    concat
  end
end

match "**/*.handlebars" do
  filter HandlebarsFilter
  minispade
  concat "templates.js"
end