Inherit python logger from parent function scope

Question

I want my function do_x to use (child) logger __main__.do_all that is defined in the parent scope do_all from which do_x is called. Instead the root logger is used by default.

Is there a way do force do_x to use the child logger __main__.do_all? Should I pass the logger as parameter to do_x, even though it is not recommended in numerous posts? Assume that I want to call do_x also from other scopes using other (child) loggers.

import logging

logging.basicConfig(format='%(asctime)s - %(name)s - %(funcName)s - %(levelname)s - %(message)s')
logger = logging.getLogger(__name__)

def do_x():
    logger.warning('doing x')

def do_all():
    logger = logging.getLogger(__name__ + '.do_all')
    logger.warning('Starting do_all')
    do_x()

def do_all_other():
    logger = logging.getLogger(__name__ + '.do_all_other')
    logger.warning('Starting do_all_other')
    do_x()

do_all()
do_all_other()

Produces

2022-09-27 11:34:40,562 - __main__.do_all - do_all - WARNING - Starting do_all
2022-09-27 11:34:40,562 - __main__ - do_x - WARNING - doing x
2022-09-27 11:34:40,562 - __main__.do_all_other - do_all_other - WARNING - Starting do_all_other
2022-09-27 11:34:40,562 - __main__ - do_x - WARNING - doing x

I want the second and the last line of the output to use __main__.do_all and __main__.do_all_other respectively

do_x() will need to know where it is called from. There is only two ways: pass the name of the parent as a param, or inspect the stack — blues
– blues, Commented Sep 26, 2022 at 15:24
No logger is really defined in the function. The call getLogger returns (creating if necessary) a specific logger instance that is managed by the logging module, regardless of where the call to getLogger is made. — chepner
– chepner, Commented Sep 26, 2022 at 18:38

blues · Accepted Answer · 2022-09-26 15:35:12Z

2

import logging
import inspect

logging.basicConfig(format='%(asctime)s - %(name)s - %(funcName)s - %(levelname)s - %(message)s')

def do_x():
    logger_name = __name__ + '.' + inspect.stack()[1].function
    logger = logging.getLogger(logger_name)
    logger.warning('some log')

def do_all():
    do_x()

def do_other():
    do_x()


do_all()
do_other()

produces

2022-09-26 17:33:06,967 - __main__.do_all - do_x - WARNING - some log
2022-09-26 17:33:06,967 - __main__.do_other - do_x - WARNING - some log

Requires a recent version of python, but works with older versions too. inspect.stack() just returns the data in a slightly different format in older versions.

answered Sep 26, 2022 at 15:35

blues

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Comments

chepner · Accepted Answer · 2022-09-26 12:36:31Z

0

The logger namespace is independent of function scopes. do_x should simply make the same call to getLogger to use the same Logger instance.

def do_x():
    logging.getLogger(__name__ + '.do_all').info('doing x')

answered Sep 26, 2022 at 12:36

chepner

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3 Comments

Pepacz Over a year ago

It does not solve for possibility of "calling do_x from other scopes using other loggers". I updated the question a bit to illustrate this issue. Think of do_x as a general function called by various parent functions. Though thanks for the answer.

chepner Over a year ago

Why do you want to use the same logger if you want different output it?

Pepacz Over a year ago

I do not want to use same logger, I want exactly the opposite in fact. I was hoping that logger variable (is it variable?) in do_x can point to the Logger instance in the functions' parent scope, depending from where do_x is called. At the same time I want to keep the code for do_x general enough so that I do not have to edit it each time I add a new call with a new logger. Let's say that do_x is some simple transformation of data and I want to log some intermediary results on the way.

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