esm-logging/docs/logging-cookbook.md

Using logging in multiple modules

Multiple calls to logging.getLogger('someLogger') return a reference to the same logger object. This is true not only within the same module, but also across modules as long as it is in the same Python interpreter process. It is true for references to the same object; additionally, application code can define and configure a parent logger in one module and create (but not configure) a child logger in a separate module, and all logger calls to the child will pass up to the parent. Here is a main module:

``javascript import * as logging from 'eslib/logging'; import * as my_module from './my_module';

// create logger with 'spam_application' var logger = logging.getLogger('spam_application'); logger.setLevel(logging.DEBUG);

// create file handler which logs even debug messages var fh = logging.FileHandler('spam.log') fh.setLevel(logging.DEBUG);

// create console handler with a higher log level var ch = logging.StreamHandler(); ch.setLevel(logging.ERROR);

// create formatter and add it to the handlers var formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s'); fh.setFormatter(formatter); ch.setFormatter(formatter);

// add the handlers to the logger logger.addHandler(fh); logger.addHandler(ch);

logger.info('creating an instance of auxiliary_module.Auxiliary')