webapp2.py 文件源码

def handle_exception(self, request, response, e):
        """Handles a uncaught exception occurred in :meth:`__call__`.

        Uncaught exceptions can be handled by error handlers registered in
        :attr:`error_handlers`. This is a dictionary that maps HTTP status
        codes to callables that will handle the corresponding error code.
        If the exception is not an ``HTTPException``, the status code 500
        is used.

        The error handlers receive (request, response, exception) and can be
        a callable or a string in dotted notation to be lazily imported.

        If no error handler is found, the exception is re-raised.

        Based on idea from `Flask`_.

        :param request:
            A :class:`Request` instance.
        :param response:
            A :class:`Response` instance.
        :param e:
            The uncaught exception.
        :returns:
            The returned value from the error handler.
        """
        if isinstance(e, HTTPException):
            code = e.code
        else:
            code = 500

        handler = self.error_handlers.get(code)
        if handler:
            if isinstance(handler, six.string_types):
                self.error_handlers[code] = handler = import_string(handler)

            return handler(request, response, e)
        else:
            # Re-raise it to be caught by the WSGI app.
            raise