Setting up rake-pipeline for use with handlebars alongside Google App Engine

Question

So here\'s what I\'m attempting to do. I\'m building an ember.js application, with a java backend running on GAE.

I\'m using handlebars, but I want them divided up i

Answer 1

Rake::Pipeline.build is the method that evaluates an Assetfile. You can imagine that your entire Assetfile is wrapped inside a Rake::Pipeline.build {} block; you shouldn't ever need to write one inside an Assetfile.

Some of the filters in the docs are hypothetical, most of those docs were written before there were any filters at all. A CoffeeScript compiler has been recently added, though.

As to your main question, I'm not sure there's a clean way to do it with the current rakep implementation. An Assetfile is just Ruby, though, so it's possible to hack something together that should work. Here's how I would write yours:

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

The if ENV['RAKEP_ENV'] bit reads an environment variable to decide whether to concatenate your JS to a single file.

So now you can run RAKEP_ENV="production" rakep build for a concatenated build, or just rakep build for a development build.