make some shared devise logic into a helper

app/helpers/sessions_helper.rb

@@ -7,4 +7,8 @@ module SessionsHelper
       nil
     end
   end
+
+  def should_display_registration_link?
+    !AppConfig[:registrations_closed] && devise_mapping.registerable? && controller_name != 'registrations'
+  end
 end

app/views/sessions/new.haml

@@ -45,7 +45,7 @@
         = f.submit t('devise.sessions.new.sign_in'), :tabindex => 4
 
 
-      - if !AppConfig[:registrations_closed] && devise_mapping.registerable? && controller_name != 'registrations'
+      - if should_display_registration_link?
         %br
         %br
         %br

app/views/sessions/new.mobile.haml

@@ -24,5 +24,5 @@
             = link_to "Forgot password?", new_password_path(resource_name)
 
 %footer
-  - if !AppConfig[:registrations_closed] && devise_mapping.registerable? && controller_name != 'registrations'
+  - if should_display_registration_link?    
     = link_to t('.sign_up'), new_registration_path(resource_name)