python - Multiple streamhandlers -

i trying beef logging in python scripts , grateful if share best practices me. have created little script (i should run python 3.4)

import logging import io import sys  def streamhandler(stream, level, format="%(asctime)s - %(name)s - %(levelname)s - %(message)s"):     ch = logging.streamhandler(stream)     ch.setlevel(level)     formatter = logging.formatter(format)     ch.setformatter(formatter)     return ch   # root logger logger = logging.getlogger()  stream = io.stringio() logger.addhandler(streamhandler(stream, logging.warn))  stream_error = io.stringio() logger.addhandler(streamhandler(stream_error, logging.error))  logger.addhandler(streamhandler(stream=sys.stdout, level=logging.debug))  print(logger) h in logger.handlers:     print(h)     print(h.level)  # 'application' code   # goes root logger! logging.debug('debug message') logging.info('info message') logging.warning('warn message') logging.error('error message') logging.critical('critical message')  print(stream.getvalue()) print(stream_error.getvalue()) 

i have 3 handlers, 2 of them write io.stringio (this seems work). need simplify testing send logs via http email service. , there streamhandler console. however, logging.debug , logging.info messages ignored on console here despite setting level explicitly low enough?!

first, didn't set level on logger itself:

logger.setlevel(logging.debug) 

also, define logger calls on logging - call on root logger. not make difference in case since didn't specify name logger, logging.getlogger() returns root logger.

wrt/ "best practices", depends on how "complex" scripts , of course on logging needs.

for self-contained simple scripts simple use cases (single known environment, no concurrent execution, simple logging file or stderr etc), simple call logging.basicconfig() , direct calls logging.whatever() enough.

for more complex, it's better use distinct config file - either in ini format or python dict (using logging.dictconfig), split script distinct module(s) or package(s) each defining it's own named logger (with logger = logging.getlogger(__name__)) , keep script "runner" code, ie: configure logging, import modules, parse command line args , call main function - preferably in try/except block log unhandled exception before crashing.