Stylesheet Engine

Contributing an additional stylesheet engine to Padrino is actually quite straightforward. For this guide, let's look at how the sass component is integrated into Padrino; a new engine follows the same steps.

Generators

Every file in padrino-gen/lib/padrino-gen/generators/components/stylesheets/ is a choice for --stylesheet, named after the file. There's no list of components to edit: adding stylesheets/myengine.rb is enough for padrino g project --stylesheet=myengine and, in an existing project, padrino g component --stylesheet=myengine. Both read the file and then call its setup_stylesheet method.

Here is the integration of Sass into the generator, in padrino-gen/generators/components/stylesheets/sass.rb:

# padrino-gen/lib/padrino-gen/generators/components/stylesheets/sass.rb

SASS_INIT = <<-SASS unless defined?(SASS_INIT)
    # Enables support for SASS template reloading in rack applications.
    # See http://nex-3.com/posts/88-sass-supports-rack for more details.
    # Store SASS files (by default) within 'app/stylesheets'.
    require 'sass/plugin/rack'
    Sass::Plugin.options[:template_location] = Padrino.root("app/stylesheets")
    Sass::Plugin.options[:css_location] = Padrino.root("public/stylesheets")
    app.use Sass::Plugin::Rack
SASS

def setup_stylesheet
  require_dependencies 'sass'
  initializer :sass, SASS_INIT.chomp
  empty_directory destination_root('/app/stylesheets')
end

require_dependencies adds the gem to the project's Gemfile. initializer writes config/initializers/sass.rb with a SassInitializer module whose registered hook runs the code in SASS_INIT, and adds register SassInitializer to app/app.rb. Sass compiles the files in app/stylesheets to public/stylesheets as requests come in, so the last line creates app/stylesheets for the source files.

Tests

Let's also add a test to ensure the stylesheet engine component generates as expected in padrino-gen/test/test_project_generator.rb:

# padrino-gen/test/test_project_generator.rb
describe 'the generator for stylesheet component' do
  it 'should properly generate for sass' do
    capture_io { generate(:project, 'sample_project', "--root=#{@apptmp}", '--renderer=haml', '--script=none', '--stylesheet=sass') }
    assert_match_in_file(/gem 'sass'/, "#{@apptmp}/sample_project/Gemfile")
    assert_match_in_file(/module SassInitializer.*Sass::Plugin::Rack/m, "#{@apptmp}/sample_project/config/initializers/sass.rb")
    assert_match_in_file(/register SassInitializer/m, "#{@apptmp}/sample_project/app/app.rb")
    assert_dir_exists("#{@apptmp}/sample_project/app/stylesheets")
  end
  ...
end

README

Finally, let's update the README for padrino-gen to list the component in padrino-gen/README.rdoc:

# padrino-gen/README.rdoc
stylesheet:: none  (default), tailwind, sass, scss

Contribute to Padrino

This completes the full integration of a stylesheet engine into Padrino. Once all of this has been finished in your GitHub fork, send us a pull request and assuming you followed these instructions properly and the engine actually works when generated, we will include the component into the next Padrino version crediting you for the contribution!