1 files changed, 82 insertions, 0 deletions
diff --git a/actionpack/lib/abstract_controller/helpers.rb b/actionpack/lib/abstract_controller/helpers.rb
new file mode 100644
index 0000000000..5efa37fde3
--- /dev/null
+++ b/actionpack/lib/abstract_controller/helpers.rb
@@ -0,0 +1,82 @@
+module AbstractController
+  module Helpers
+    extend ActiveSupport::Concern
+
+    include Renderer
+
+    included do
+      extlib_inheritable_accessor(:_helpers) { Module.new }
+    end
+
+    module ClassMethods
+      # When a class is inherited, wrap its helper module in a new module.
+      # This ensures that the parent class's module can be changed
+      # independently of the child class's.
+      def inherited(klass)
+        helpers = _helpers
+        klass._helpers = Module.new { include helpers }
+
+        super
+      end
+
+      # Declare a controller method as a helper. For example, the following
+      # makes the +current_user+ controller method available to the view:
+      #   class ApplicationController < ActionController::Base
+      #     helper_method :current_user, :logged_in?
+      #
+      #     def current_user
+      #       @current_user ||= User.find_by_id(session[:user])
+      #     end
+      #
+      #      def logged_in?
+      #        current_user != nil
+      #      end
+      #   end
+      #
+      # In a view:
+      #  <% if logged_in? -%>Welcome, <%= current_user.name %><% end -%>
+      #
+      # ==== Parameters
+      # meths<Array[#to_s]>:: The name of a method on the controller
+      #   to be made available on the view.
+      def helper_method(*meths)
+        meths.flatten.each do |meth|
+          _helpers.class_eval <<-ruby_eval, __FILE__, __LINE__ + 1
+            def #{meth}(*args, &blk)
+              controller.send(%(#{meth}), *args, &blk)
+            end
+          ruby_eval
+        end
+      end
+
+      # Make a number of helper modules part of this class' default
+      # helpers.
+      #
+      # ==== Parameters
+      # *args<Array[Module]>:: Modules to be included
+      # block<Block>:: Evalulate the block in the context
+      #   of the helper module. Any methods defined in the block
+      #   will be helpers.
+      def helper(*args, &block)
+        args.flatten.each do |arg|
+          case arg
+          when Module
+            add_template_helper(arg)
+          end
+        end
+        _helpers.module_eval(&block) if block_given?
+      end
+
+      private
+      # Makes all the (instance) methods in the helper module available to templates
+      # rendered through this controller.
+      #
+      # ==== Parameters
+      # mod<Module>:: The module to include into the current helper module
+      #   for the class
+      def add_template_helper(mod)
+        _helpers.module_eval { include mod }
+      end
+    end
+  end
+end