    # File lib/chef/run_list/run_list_expansion.rb, line 52
          def initialize(environment, run_list_items, source=nil)
            @environment = environment
            @errors = Array.new

            @run_list_items = run_list_items.dup
            @source = source

            @default_attrs = Mash.new
            @override_attrs = Mash.new

            @recipes = Chef::RunList::VersionedRecipeList.new

            @applied_roles = {}
          end