def cache_resource(dest_dir=@local_cache_dir, options={})
      unless dest_dir
        raise ArgumentError, "Must specify destination directory when creating resource", caller
      end
      self.local_cache_dir=dest_dir
      @size = update_cache(@url, @local_path, options)
      if options[:include_pack_gz]
        @relative_local_path_pack_gz = "#{@relative_local_path}.pack.gz"
        @local_path_pack_gz = "#{dest_dir}/#{@relative_local_path_pack_gz}"
        @size_pack_gz = update_cache(@url_pack_gz, @local_path_pack_gz, options)
      end
      @signature_verified ? @size : @signature_verified
    end
def cache_resource(dest_dir=@local_cache_dir, options={})
      unless dest_dir
        raise ArgumentError, "Must specify destination directory when creating resource", caller
      end
      self.local_cache_dir=dest_dir
      @size = update_cache(@url, @local_path, options)
      if options[:include_pack_gz]
        @relative_local_path_pack_gz = "#{@relative_local_path}.pack.gz"
        @local_path_pack_gz = "#{dest_dir}/#{@relative_local_path_pack_gz}"
        @size_pack_gz = update_cache(@url_pack_gz, @local_path_pack_gz, options)
      end
      @signature_verified ? @size : @signature_verified
    end
Copies the resource referenced in Resource#url
 to the local cache.

 If the resource is successully cached locally and the
 signature is verified the size of the resource is retured.

 If the signature is not verified then false is returned.