From 8028a5cf15753c283b7308a32ecc4651db33c6c9 Mon Sep 17 00:00:00 2001 From: Vinay Sajip Date: Sat, 30 Mar 2013 11:56:18 +0000 Subject: [PATCH] Updated logging cookbook with additional example for output using str.format(). --- Doc/howto/logging-cookbook.rst | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/Doc/howto/logging-cookbook.rst b/Doc/howto/logging-cookbook.rst index 8d58c8486a7..47406aa9eb7 100644 --- a/Doc/howto/logging-cookbook.rst +++ b/Doc/howto/logging-cookbook.rst @@ -1096,6 +1096,40 @@ parentheses go around the format string and the arguments, not just the format string. That's because the __ notation is just syntax sugar for a constructor call to one of the XXXMessage classes. +If you prefer, you can use a :class:`LoggerAdapter` to achieve a similar effect +to the above, as in the following example:: + + import logging + + class Message(object): + def __init__(self, fmt, args): + self.fmt = fmt + self.args = args + + def __str__(self): + return self.fmt.format(*self.args) + + class StyleAdapter(logging.LoggerAdapter): + def __init__(self, logger, extra=None): + super(StyleAdapter, self).__init__(logger, extra or {}) + + def log(self, level, msg, *args, **kwargs): + if self.isEnabledFor(level): + msg, kwargs = self.process(msg, kwargs) + self.logger._log(level, Message(msg, args), (), **kwargs) + + logger = StyleAdapter(logging.getLogger(__name__)) + + def main(): + logger.debug('Hello, {}', 'world!') + + if __name__ == '__main__': + logging.basicConfig(level=logging.DEBUG) + main() + +The above script should log the message ``Hello, world!`` when run with +Python 3.2 or later. + .. currentmodule:: logging