app.py 文件源码

def logger(self):
        """A :class:`logging.Logger` object for this application.  The
        default configuration is to log to stderr if the application is
        in debug mode.  This logger can be used to (surprise) log messages.
        Here some examples::

            app.logger.debug('A value for debugging')
            app.logger.warning('A warning occurred (%d apples)', 42)
            app.logger.error('An error occurred')

        .. versionadded:: 0.3
        """
        if self._logger and self._logger.name == self.logger_name:
            return self._logger
        with _logger_lock:
            if self._logger and self._logger.name == self.logger_name:
                return self._logger
            from flask.logging import create_logger
            self._logger = rv = create_logger(self)
            return rv