example.rb

MyApp.controllers :product do
  parent :shop, :optional => true
  parent :category, :optional => true

  get :show, :with => :id do
    # generated url:   "/(shop/#{params[:shop_id]}/)(category/#{params[:category_id]}/)product/show/#{params[:id]}"
    # url_for(:product, :show, :id => 10) => "/product/show/10"
    # url_for(:product, :show, :shop_id => 5, :id => 10) => "/shop/5/product/show/10"
    # url_for(:product, :show, :shop_id => 5, :category_id => 1, :id => 10) => "/shop/5/category/1/product/show/10"
  end
end