Question

I’ve got same routes inside namespace and subdomain constraint.

First is used on production, second in development. How can remove this duplication?

constraints :subdomain => 'api' do
    scope :module => "api" do
      resources :users
      resources :orders
    end     
end

namespace :api do
    resources :users
    resources :orders
end    

Answer 1

Well, do ... end creates a block. If you have a block that’s repeated you can instead save it to a variable by turning it into a Proc, by passing it to Proc.new or proc (the latter is just a shortcut for the former):

res = Proc.new do
  resources :users
  resources :orders
end

Then you can pass the Proc (res) as a block argument to any method that expects a block by prepending it with &:

constraints :subdomain => 'api' do
  scope :module => 'api', &res
end

namespace :api, &res

Here’s a great article on using blocks, Procs, and lambdas in Ruby.