# File lib/nanoc/base/compilation/outdatedness_checker.rb, line 20
    def initialize(params={})
      @site = params[:site] or raise ArgumentError,
        'Nanoc::OutdatednessChecker#initialize needs a :site parameter'
      @checksum_store = params[:checksum_store] or raise ArgumentError,
        'Nanoc::OutdatednessChecker#initialize needs a :checksum_store parameter'
      @dependency_tracker = params[:dependency_tracker] or raise ArgumentError,
        'Nanoc::OutdatednessChecker#initialize needs a :dependency_tracker parameter'

      @basic_outdatedness_reasons = {}
      @outdatedness_reasons = {}
      @objects_outdated_due_to_dependencies = {}
    end