Question

I’m working on a Sinatra app that contains about 10 different components of functionality. We’d like to be able to mix and match these components into separate instances of the application, configured entirely from a config.yaml file that looks something like:

components:

- route: '/chunky'
  component_type: FoodLister
  component_settings: 
    food_type: bacon
    max_items: 400

- route: 'places/paris'
  component_type: Mapper
  component_settings: 
    latitude: 48.85387273165654
    longitude: 2.340087890625  

- route: 'places/losangeles'
  component_type: Mapper
  component_settings:
    latitude: 34.043556504127466
    longitude: -118.23486328125

As you can see, components can be instantiated more than once, each with their own contextual settings.

Each component consists of at least one route, with the “route” property from the config file used for the base.

What is the best way to organize and instantiate the module code?

Answer 1

This is similar to include’s proposal, but it doesn’t require access to the rackup file.

Write your various Handlers like:

class FoodHandler < Sinatra::Base
  get '/chunky/:food' do
    "Chunky #{params[:food]}!"
  end
end

Then in your main application file:

require './lib/handlers/food_handler.rb'

class Main < Sinatra::Base
  enable :sessions
  ... bla bla bla
  use FoodHandler
end

I’ve used this kind of structure to build some fairly complex Sinatra apps. It scales just as well as Rails.

EDIT

To have your config file define the routes, you could do something like this:

class PlacesHandler < Sinatra::Base
  # Given your example, this would define 'places/paris' and 'places/losangeles'
  CONFIG['components'].select { |c| c['compontent_type'] == 'Mapper' }.each do |c|
    get c['route'] do
      @latitude = c['component_settings']['latitude']
      @longitude = c['component_settings']['longitude']
    end
  end
end