On 12/10/2010 9:06 PM, Nick Coghlan wrote:

Anyway, the shortest way I could find of setting this up (debug
silenced, info written to stdout, warning and above written to
stderr):

  import sys, logging
  root = logging.getLogger()
  # Turns out the level of the root logger is set to WARNING by default
  # That should be much easier to find out from the logging docs!
  root.setLevel(logging.DEBUG)
  # Send WARNING and above to stderr
  # basicConfig() is no help, since it sets the specified level on the
root logger
  # but NOT on the default handler it installs. To emulate console output
  # we want to skip the formatting anyway.
  err = logging.StreamHandler()
  err.setLevel(logging.WARNING)
  root.addHandler(err)
  # Send INFO to stdout
  def is_info(record):
      return record.levelno == logging.INFO
  out = logging.StreamHandler(stream=sys.stdout)
  out.addFilter(is_info)
  root.addHandler(out)

Wow, that's way longer than I expected... almost as long as my "cheap logger". Greg didn't flesh out the "setup" stuff, but you have, so this is educational. Thanks.

Not sure I want my INFO to go to stdout, by the way. That corresponds to "debugging print statement" behavior, but even my "cheap logger" actually puts stuff in a file instead, and gets it out of the way of the normal output.

I'd suggest that this be "simplified" to put all the messages in the same (disk) file, but then I'm sure that there are other preferences than mine... you clearly thought about what you wanted/thought would be useful, in coming up with the above.

On 12/10/2010 9:24 PM, Nick Coghlan wrote:

This could actually make a reasonably good basic for a "task oriented"
subsection of the logging documentation. Something like:

Yep, agree. But sadly, for each point, there may be multiple options (your StreamHandler, but I'd want a FileHandler; your separation of messages by level, my wanting them combined; etc.)

Your comment about basicConfig setting the level on the root logger, but not on the default handler making it useless is opaque to me, but is there perhaps room for another basic setup API that could get the setup code down to a line or two in simple cases? Maybe 3 parameters:

1. minimum level to be generated, which would be passed through to the root logger and anything else defined by this basic setup API

2. whether debug and info should go to the same or different stream/file as warn+ messages. Maybe this is a stream or filename or None, the last implying to use the warn+ output.

3. Where to send the warn+ output.

maybe a 4. Maximum (size, count) of the round-robin log files, assuming that either or both of 2 & 3 specify files.

Would that be a useful set of functionality to bundle? And could it be extended, when the user wants more power, or would it have to be replaced, because it gets in the way of the user that wants more power?