# File lib/rubygems/package.rb, line 106
    def initialize(vals)
      unless vals[:name] && vals[:size] && vals[:prefix] && vals[:mode]
        raise ArgumentError, ":name, :size, :prefix and :mode required"
      end
      vals[:uid] ||= 0
      vals[:gid] ||= 0
      vals[:mtime] ||= 0
      vals[:checksum] ||= ""
      vals[:typeflag] ||= "0"
      vals[:magic] ||= "ustar"
      vals[:version] ||= "00"
      vals[:uname] ||= "wheel"
      vals[:gname] ||= "wheel"
      vals[:devmajor] ||= 0
      vals[:devminor] ||= 0
      FIELDS.each {|x| instance_variable_set "@#{x.to_s}", vals[x]}
      @empty = vals[:empty]
    end