module ActsCrummy #:nodoc:

  # This module is mixed into ActiveRecord::Base to provide methods to help define

  # the direct hierarcy in the model structure of a project, so that breadcrumbs

  # can be rendered dynamically from it.



  module HasParent



    # the self.included/class << base trick is all for the sake

    # seemingly neceesary class variable @@parent_label

    def self.included(base) #:nodoc:



      # only apply this to inheriting classes, not to the parent itself

      # (probably ActiveRecord::Base)

      def base.inherited(subclass)

        super if defined? super



        class << subclass

          def is_child_to lbl #:doc:

            if method_defined? :parent

              raise ArgumentError, 'Only one parent can be defined for a given model.'

            end



            # this way we don't add the parent method unless

            # it's actually going to be used.  if we just added

            # to the class outright it may mess with the model

            # definition.

            send(:define_method, :parent) do

              send(lbl)

            end

          end

        end

      end

    end

  end

end