如何配置Python 2.3日志消息的格式？

Question

In Python 2.4 and later, configuring the logging module to have a more basic formatting is easy:

logging.basicConfig(level=opts.LOGLEVEL, format="%(message)s")

but for applications which need to support Python 2.3 it seems more difficult, because the logging API was overhauled in Py2.4. In particular, basicConfig doesn't take any arguments. Trying a variation on the sole example in the Py2.3 documentation, I get this:

try:
    logging.basicConfig(level=opts.LOGLEVEL, format="%(message)s")
except:
    logging.getLogger().setLevel(opts.LOGLEVEL)
    h = logging.StreamHandler()
    h.setFormatter(logging.Formatter("%(message)s"))
    logging.getLogger().addHandler(h)

but calling this root logger in Py2.3, eg

logging.info("Foo")

gives duplicated output:

Foo
INFO:root:Foo

I can't find a way to modify the format of the existing handler on the root logger in Py2.3 (the "except" block above), hence the "addHandler" call that's producing the duplicated output. Is there a way to set the format of the root logger without this duplication? Thanks!

Answer 1

except: without exception class[es] is a good way to get in trouble. I believe logging module in Python 2.3 has basicConfig() function, but with less options. Since it accepts **kwargs it may fail at any moment after doing some job. I think it already installed a handler with default format then failed to configure something. After catching exception you have installed another handler. Having 2 handlers you get 2 messages for each event. The simplest way in your case: avoid using basicConfig() at all and configure logging manually. And never use except: if you don't reraise or log caught exception.