Add table_name_prefix to Engine's namespace automatically

railties/lib/rails/engine.rb

@@ -201,11 +201,19 @@ def endpoint(endpoint = nil)
       end
 
       def namespace(mod)
+        # TODO: extract that into a module
+        engine_name(generate_railtie_name(mod))
+
         _railtie = self
+        name = engine_name
         mod.singleton_class.instance_eval do
           define_method(:_railtie) do
             _railtie
           end
+
+          define_method(:table_name_prefix) do
+            "#{name}_"
+          end
         end
       end
     end

railties/lib/rails/railtie.rb

@@ -167,8 +167,13 @@ def abstract_railtie?
 
       def railtie_name(name = nil)
         @railtie_name = name.to_s if name
-        @railtie_name ||= ActiveSupport::Inflector.underscore(self.name).gsub("/", "_")
+        @railtie_name ||= generate_railtie_name(self.name)
       end
+
+      protected
+        def generate_railtie_name(class_or_module)
+          ActiveSupport::Inflector.underscore(class_or_module).gsub("/", "_")
+        end
     end
 
     delegate :railtie_name, :to => "self.class"

railties/test/railties/engine_test.rb

@@ -408,6 +408,8 @@ class MyMailer < ActionMailer::Base
 
       boot_rails
 
+      assert_equal "bukkits_", Bukkits.table_name_prefix
+      assert_equal "bukkits", Bukkits::Engine.engine_name
       assert_equal Bukkits._railtie, Bukkits::Engine
       assert ::Bukkits::MyMailer.method_defined?(:foo_path)
       assert !::Bukkits::MyMailer.method_defined?(:bar_path)