title: Rails: Including a Concern with a constant within a Concern
body: <p>I have concern in which I store constants:</p>
  
  <pre><code>module Group::Constants
    extend ActiveSupport::Concern
  
    MEMBERSHIP_STATUSES = %w(accepted invited requested
      rejected_by_group rejected_group)
  end
  </code></pre>
  
  <p>And another concern that I wish to use these constants:</p>
  
  <pre><code>module User::Groupable
    extend ActiveSupport::Concern
    include Group::Constants
  
    MEMBERSHIP_STATUSES.each do |status_name|
      define_method "#{status_name}_groups" do
        groups.where(:user_memberships =&gt; {:status =&gt; status_name})
      end
    end
  end
  </code></pre>
  
  <p>Unfortunately, this results in a routing error:</p>
  
  <pre><code>uninitialized constant User::Groupable::MEMBERSHIP_STATUSES
  </code></pre>
  
  <p>It looks like the first concern isn't loading properly in the second concern. If that's the case, what can I do about it?</p>