Added first part of inherits, but will have to refactor compiling to happen after everything else before this will work.

Author: Michael Bleigh

lib/grape/api.rb

@@ -188,6 +188,11 @@ def http_digest(options = {}, &block)
       def mount(mounts)
         mounts.each_pair do |app, path|
           next unless app.respond_to?(:call)
+          
+          if app.is_a?(Class) && app < Grape::API
+            app.inherit(settings_stack)
+          end
+
           route_set.add_route(app, 
             path_info: compile_path(path, false)
           )
@@ -357,7 +362,12 @@ def build_endpoint(&block)
       def inherited(subclass)
         subclass.reset!
       end
-      
+
+      def inherit(other_stack)
+        settings_stack.unshift *other_stack
+        raise settings_stack.inspect
+      end
+
       def route_set
         @route_set ||= Rack::Mount::RouteSet.new
       end

spec/grape/api_spec.rb

@@ -778,5 +778,46 @@ class CommunicationError < RuntimeError; end
         last_response.body.should == 'MOUNTED'
       end
     end
+
+    context 'with another Grape API' do
+      class ExampleProtectedAPI < Grape::API
+        get '/protected' do
+          "YOU'RE IN!"
+        end
+      end
+
+      class ExampleV1API < Grape::API
+        get "/old" do
+          "YOU'RE OLD! #{version}"
+        end
+      end
+
+      before do
+        subject.scope :v1 do
+          version :v1
+          mount ExampleV1API => '/'
+        end
+
+        subject.scope :authenticated do
+          before do
+            error!("Not Authorized", 401) unless params[:authorized] == 'true'
+          end
+          mount ExampleProtectedAPI => '/private'
+        end
+      end
+
+      it 'should be able to access the old API namespaced properly' do
+        get '/v1/old'
+        last_response.body.should == "YOU'RE OLD! v1"
+      end
+
+      it 'should run before filters that are inherited' do
+        get '/private/protected'
+        last_response.status.should == 401
+        get '/private/protected?authorized=true'
+        last_response.status.should == 200
+        last_response.body.should == "YOU'RE IN!"
+      end
+    end
   end
 end