Conditional based on whether or not a module is being used

Vinay Sajip vinay_sajip at
Sat Mar 6 23:38:57 CET 2010

On Mar 5, 9:29 pm, Pete Emerson <pemer... at> wrote:
> I have written my first module called "logger" that logs to syslog via
> the syslog module but also allows forloggingto STDOUT in debug mode
> at multiple levels (to increase verbosity depending on one's need), or
> both. I've looked at theloggingmodule and while it might suit my
> needs, it's overkill for me right now (I'm still *very* much a python
> newbie).

Overkill in what sense? You just need to write a few lines of code to
be able to use the logging package which comes with Python:

import logging, logging.handlers, sys
logging.basicConfig(level=logging.DEBUG, stream=sys.stdout)
# default logs to syslog at (localhost, 514) with facility LOG_USER
# you can change the default to use e.g. Unix domain sockets and a
different facility

So you're experienced enough and have time enough to write your own
logger module, but too much of a newbie to use a module which is part
of Python's included batteries? If you're writing something like
logging to learn about it and what the issues are, that's fair enough.
But I can't see what you mean by overkill, exactly. The three lines
above (or thereabouts) will, I believe, let you log to syslog and to
stdout...which is what you say you want to do.

> I want to write other modules, and my thinking is that it makes sense
> for those modules to use the "logger" module to do thelogging, if and
> only if the parent using the other modules is also using the logger
> module.
> In other words, I don't want to force someone to use the "logger"
> module just so they can use my other modules, even if the "logger"
> module is installed ... but I also want to take advantage of it if I'm
> using it.
> Now that I've written that, I'm not sure that makes a whole lot of
> sense. It seems like I could say, "hey, this person has the 'logger'
> module available, let's use it!".
> Thoughts?

Well, the logging package is available in Python and ready for use and
pretty much battle tested, so why not use that? Are you planning to
use third-party libraries in your Python work, or write everything
yourself? If you are planning to use third party libraries, how would
their logging be hooked into your logger module? And if not, is it
good to have two logging systems in parallel?

Of course as the maintainer of Python's logging package, you'd expect
me to be biased in favour of it. You maybe shouldn't let that sway
you ;-)


Vinay Sajip

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