CODEWITHSUNDEEP
pythonlogging
Mad Physicist
Mad Physicist

Reputation: 114468

Force recreation of logger for a given name in python

I get a regular non-root logger of the default type:

logger = logging.getLogger('a')

Now I want to change the type and get a new logger for the same name:

logging.setLoggerClass(type('NewLoggerClass', (logging.Logger,), {}))
logger = logging.getLogger('a')

I would like the second call to getLogger to respect the new logger class I set. However, logger remains the same instance of logging.Logger instead of __main__.NewLoggerClass.

How do I either remove an existing logger for a given name, or replace it with one of a different type?

Upvotes: 0

Views: 71

Answers (2)

pepoluan
pepoluan

Reputation: 6808

If in doubt ... "Use the source, Luke!"

So spelunking into logging/__init__.py, one can see that a call to logging.getLogger actually invokes Logger.manager.getLogger.

Logger.manager is itself an instance of Manager that was instatiated on module load.

Hunting in the Manager class shows that it checks for existing logger objects in self.loggerDict. This attribute acts as the 'cache' for instantiated logger class.

So if you want to replace a certain logger with a new logger class, you probably can do it by deleting it first. Maybe like this:

    del logging.Logger.manager.loggerDict['a']
    logging.setLoggerClass(type('NewLoggerClass', (logging.Logger,), {}))
    logger = logging.getLogger('a')

Try it out!

Upvotes: 1

Vinay Sajip
Vinay Sajip

Reputation: 99465

You can't do this (other than low-level hackery) once a logger has been created. You'll need to call setLoggerClass() before you instantiate any loggers via getLogger().

Upvotes: 1

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