Change documentation of metal anonymous class

Make it clearer

[ci skip]

1 files changed, 10 insertions, 5 deletions

diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index ff0a7bf6ce..dc880cd866 100644
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -3,11 +3,16 @@ require "action_controller/log_subscriber"
 require "action_controller/metal/params_wrapper"
 
 module ActionController
-  # The <tt>metal</tt> anonymous class is simple workaround the ordering issues there are with modules.
-  # They need to be included in specific order which makes it impossible for 3rd party libs (like ActiveRecord)
-  # to hook up with its own functionality. Having anonymous super class type of Metal with <tt>AbstractController::Rendering</tt>
-  # included, allows us to include <tt>ActionView::Rendering</tt> (which implements <tt>AbstractController::Rendering</tt> interface)
-  # after the <tt>AbstractController::Rendering</tt> and before <tt>ActionController::Rendering</tt>.
+  # The <tt>metal</tt> anonymous class was introduced to solve issue with including modules in <tt>ActionController::Base</tt>.
+  # Modules needes to be included in particluar order. First wee need to have <tt>AbstractController::Rendering</tt> included,
+  # next we should include actuall implementation which would be for example <tt>ActionView::Rendering</tt> and after that
+  # <tt>ActionController::Rendering</tt>. This order must be preserved and as we want to have middle module included dynamicaly
+  # <tt>metal</tt> class was introduced. It has <tt>AbstractController::Rendering</tt> included and is parent class of
+  # <tt>ActionController::Base</tt> which includes <tt>ActionController::Rendering</tt>. If we include <tt>ActionView::Rendering</tt>
+  # beetween them to perserve the required order, we can simply do this by:
+  #
+  #   ActionController::Base.superclass.send(:include, ActionView::Rendering)
+  #
   metal = Class.new(Metal) do
     include AbstractController::Rendering
   end