Comprehensive example of adding a loglevel to Python logging module

addloglevel.py

"""
Taken from StackOverflow
This is the cleanest, most correct and thorough method I've seen
"""

def addLoggingLevel(levelName, levelNum, methodName=None):
    """
    Comprehensively adds a new logging level to the `logging` module and the
    currently configured logging class.

    `levelName` becomes an attribute of the `logging` module with the value
    `levelNum`. `methodName` becomes a convenience method for both `logging`
    itself and the class returned by `logging.getLoggerClass()` (usually just
    `logging.Logger`). If `methodName` is not specified, `levelName.lower()` is
    used.

    To avoid accidental clobberings of existing attributes, this method will
    raise an `AttributeError` if the level name is already an attribute of the
    `logging` module or if the method name is already present

    Example
    -------
    >>> addLoggingLevel('TRACE', logging.DEBUG - 5)
    >>> logging.getLogger(__name__).setLevel("TRACE")
    >>> logging.getLogger(__name__).trace('that worked')
    >>> logging.trace('so did this')
    >>> logging.TRACE
    5

    Quick reminder:
        CRITICAL=50,ERROR=40,WARNING=30,INFO=20,DEBUG=10,NOTSET=0

    When you set a log level, you are saying emit events for log
    levels that are greater than that value. Keep that in mind.
    """
    if not methodName:
        methodName = levelName.lower()

    if hasattr(logging, levelName):
        raise AttributeError(
            '{} already defined in logging module'.format(levelName))
    if hasattr(logging, methodName):
        raise AttributeError(
            '{} already defined in logging module'.format(methodName))
    if hasattr(logging.getLoggerClass(), methodName):
        raise AttributeError(
            '{} already defined in logger class'.format(methodName))

    # This method was inspired by the answers to Stack Overflow post
    # http://stackoverflow.com/q/2183233/2988730, especially
    # http://stackoverflow.com/a/13638084/2988730
    def logForLevel(self, message, *args, **kwargs):
        if self.isEnabledFor(levelNum):
            self._log(levelNum, message, args, **kwargs)

    def logToRoot(message, *args, **kwargs):
        logging.log(levelNum, message, *args, **kwargs)

    logging.addLevelName(levelNum, levelName)
    setattr(logging, levelName, levelNum)
    setattr(logging.getLoggerClass(), methodName, logForLevel)
    setattr(logging, methodName, logToRoot)