An example implementation of automatic controllers in Sinatra.

sinatra-controllers.rb

require 'sinatra'
require 'rack/test'

class FooController
  def index
    "Hello, foo!"
  end
end

class BarController
  def self.default_path
    "/bar"
  end

  def index
    "Hello, bar!"
  end
end

module Sinatra
  module Controllers
    def register_controller(controller, params = {})
      @controller_map_list ||= ControllerMapList.new
      @controller_map_list << ControllerMapping.new(controller, params)
    end

    def controller_map_list
      @controller_map_list
    end

    def self.registered(app)
      app.helpers do
        def find_controller
          self.class.controller_map_list.find_match(request.path)
        end
      end
      
      app.before do
        @controller = find_controller
      end
    end
    
  end

  class ControllerMapList
    def initialize
      @list = []
    end

    def <<(mapping)
      @list << mapping
    end

    def find_match(path)
      match = @list.find { |mapping| mapping.match(path) }
      match.controller.new unless match.nil?
    end

  end

  class ControllerMapping
    attr_reader :controller
    def initialize(controller, params)
      @controller = controller
      @path = params[:path]
      @path ||= controller.default_path if controller.respond_to?(:default_path)
    end
    
    def match(request_path)
      request_path.start_with?(@path)
    end

  end
end

class ExampleApp < Sinatra::Base
  register Sinatra::Controllers

  register_controller FooController, :path => '/foo'
  register_controller BarController
  
  get "/foo/" do
    @controller.index
  end

  get "/bar/" do
    @controller.index
  end
end

describe "Sinatra::Controllers" do
  include Rack::Test::Methods

  def app
    ExampleApp.new
  end

  it "works" do
    get "/foo/"
    last_response.should be_ok
    last_response.body.should == "Hello, foo!"
  end

  it "works" do
    get "/bar/"
    last_response.should be_ok
    last_response.body.should == "Hello, bar!"
  end
end