[Python-Dev] Planned changes to logging (original) (raw)

Adam Souzis adamsz at gmail.com
Thu Jul 15 07:52:08 CEST 2004

(belatedly...) These are good changes, expecially the new basicConfig constructor, but I'd like point out two issues with the logging package that i think can easily be addressed:

One is a usability bug: calling fileConfig() disables any logger objects already created that are not explicitly specified in the log config file. Since loggers are often created when a module is imported, it's hard to keep track of the order in which loggers are created, leading to unexpected behavior because an unspecifed logger created after the call to fileConfig behave differently -- it will inherit its settings from its parent logger. Here's an example illustrating the problem:

import logging, logging.config import mymodule #this module contains a line like log = logging.getLogger("mymodule")

if name == 'main': loggging.config.fileConfig("log.config") #mymodule.log is now disabled! #this seems like a bad design -- difficult to figure out what's going on #work-around: re-enable the loggers for logger in logging.Logger.manager.loggerDict.itervalues(): logger.disabled = 0

Second, i'd recommend a minor change that would greatly increase the flexibility of the architecture: store the entire keyword dictionary in the LogRecord, not just exc_info -- that way arbitrary objects could be passed to particular handlers or formatters that know how to use them. Some use cases for this:

thanks, adam

On Sun, 27 Jun 2004 23:52:03 +0100, Vinay Sajip <vinay_sajip at red-dove.com> wrote:

I'm planning to check in some changes to the logging package. I'd appreciate comments on the following:

1. A backwards-compatible change to basicConfig(), making simple configuration of logging easier than before. For example, to change the level of the root logger to DEBUG: logging.basicConfig(level=logging.DEBUG) For example, to change the message format: logging.basicConfig(format="%(asctime)s %(levelname)-5s %(message)s") To log to a file in append mode (for write mode, add a filemode="w" argument): logging.basicConfig(filename="/logs/myapp.log") To log to an existing stream: s = open("/logs/myapp.log", "w") ... logging.basicConfig(stream=s) 2. Refactoring of RotatingFileHandler into BaseRotatingHandler and RotatingFileHandler. The reason for this is the addition of a new class, TimedRotatingFileHandler, which rotates files based on time-dependent criteria. (See SF patch #921318 for more details). 3. Logger.log() changed to throw a TypeError if raiseExceptions is set and the level passed in is not an integer. If the changes seem generally acceptable, then I'll also add a section in the docs which describes the above basic use cases under a "Basic use of the logging package" section which appears earlier in the logging docs than it does currently. Except for the documentation changes, I'm planning to commit by 3 July. Thanks, Vinay

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