1 files changed, 37 insertions, 0 deletions
diff --git a/railties/lib/rails/railtie/configurable.rb b/railties/lib/rails/railtie/configurable.rb
new file mode 100644
index 0000000000..7f42fae10a
--- /dev/null
+++ b/railties/lib/rails/railtie/configurable.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require "active_support/concern"
+
+module Rails
+  class Railtie
+    module Configurable
+      extend ActiveSupport::Concern
+
+      module ClassMethods
+        delegate :config, to: :instance
+
+        def inherited(base)
+          raise "You cannot inherit from a #{superclass.name} child"
+        end
+
+        def instance
+          @instance ||= new
+        end
+
+        def respond_to?(*args)
+          super || instance.respond_to?(*args)
+        end
+
+        def configure(&block)
+          class_eval(&block)
+        end
+
+        private
+
+          def method_missing(*args, &block)
+            instance.send(*args, &block)
+          end
+      end
+    end
+  end
+end