def create_directive(tag_name, tag_buf)
      if library.has_directive?(tag_name)
        dir = library.directive_create(tag_name, tag_buf, self)
        if dir.is_a?(Tags::Directive)
          @directives << dir
          dir
        end
      else
        log.warn "Unknown directive @!#{tag_name}" +
                 (object ? " in file `#{object.file}` near line #{object.line}" : "")
        nil
      end
    rescue Tags::TagFormatError
      log.warn "Invalid directive format for @!#{tag_name}" +
               (object ? " in file `#{object.file}` near line #{object.line}" : "")
      nil
    end
def create_directive(tag_name, tag_buf)
      if library.has_directive?(tag_name)
        dir = library.directive_create(tag_name, tag_buf, self)
        if dir.is_a?(Tags::Directive)
          @directives << dir
          dir
        end
      else
        log.warn "Unknown directive @!#{tag_name}" +
                 (object ? " in file `#{object.file}` near line #{object.line}" : "")
        nil
      end
    rescue Tags::TagFormatError
      log.warn "Invalid directive format for @!#{tag_name}" +
               (object ? " in file `#{object.file}` near line #{object.line}" : "")
      nil
    end
Creates a new directive using the registered {#library}
 @return [Tags::Directive] the directive object that is created