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| -rw-r--r-- | Doc/library/logging.rst | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/Doc/library/logging.rst b/Doc/library/logging.rst index b11dbc5..17da172 100644 --- a/Doc/library/logging.rst +++ b/Doc/library/logging.rst @@ -146,15 +146,35 @@ messages:: INFO:root:So should this WARNING:root:And this, too +This example also shows how you can set the logging level which acts as the +threshold for tracking. In this case, because we set the threshold to +``DEBUG``, all of the messages were printed. + +If you want to set the logging level from a command-line option such as:: + + --log=INFO + +and you have the value of the parameter passed for ``--log`` in some variable +*loglevel*, you can use:: + + getattr(logging, loglevel.upper()) + +to get the value which you'll pass to :func:`basicConfig` via the *level* +argument. You may want to error check any user input value, perhaps as in the +following example:: + + # assuming loglevel is bound to the string value obtained from the + # command line argument. Convert to upper case to allow the user to + # specify --log=DEBUG or --log=debug + numeric_level = getattr(logging, loglevel.upper(), None) + assert numeric_level is not None, 'Invalid log level: %s' % loglevel + logging.basicConfig(level=numeric_level, ...) + The call to :func:`basicConfig` should come *before* any calls to :func:`debug`, :func:`info` etc. As it's intended as a one-off simple configuration facility, only the first call will actually do anything: subsequent calls are effectively no-ops. -This example also shows how you can set the logging level which acts as the -threshold for tracking. In this case, because we set the threshold to -``DEBUG``, all of the messages were printed. - If you run the above script several times, the messages from successive runs are appended to the file *example.log*. If you want each run to start afresh, not remembering the messages from earlier runs, you can specify the *filemode* |