Logging messages with dictionary args in Python 2.4b1 leads to exception

From: Stefan Behnel (behnel_ml_at_dvs1.informatik.tu-darmstadt.de)
Date: 10/19/04 

Date: Tue, 19 Oct 2004 15:32:18 +0200

Hi!

I'm trying to do this in Py2.4b1:

-------------------------------
import logging
values = {'test':'bla'}
logging.log(logging.FATAL, 'Test is %(test)s', values)
-------------------------------

This leads to en exception:

-----------------------------
Traceback (most recent call last):
   File "/usr/lib/python2.4/logging/__init__.py", line 692, in emit
     msg = self.format(record)
   File "/usr/lib/python2.4/logging/__init__.py", line 578, in format
     return fmt.format(record)
   File "/usr/lib/python2.4/logging/__init__.py", line 368, in format
     record.message = record.getMessage()
   File "/usr/lib/python2.4/logging/__init__.py", line 239, in getMessage
     msg = msg % self.args
TypeError: format requires a mapping
-----------------------------

Now, values /is/ a mapping. I looked into logging/__init__.py, but I can
only see that the '*args' parameter (as which 'values' is fed in) should
have been unpacked like this in logging.log():

apply(root.log, (level, msg)+args, kwargs)

Which should lead to the second argument being '(level, msg, args)' in my
understanding and which should allow using dicts when doing this later on
in LogRecord:

msg = msg % self.args

Now, I'm somewhat confused that this doesn't work and I'm also worried
that this is only done in the module methods and not inside the class that
actually handles the logging (the root object in this case). This should
encourage a diverting behaviour of the module methods and the Logger
object methods with the same name. This looks like a bug to me. Adding the
tuple should /only/ be done inside the class, not in the module functions.

Wouldn't it be better to handle dictionaries directly inside LogRecord?
Something like this would do the trick:

-----------------------
if len(self.args) == 1:
   msg = msg % self.args[0] # may be a single value or a dictionary
else:
   msg = msg % self.args # looks like a value tuple
-----------------------

Could anyone please comment on this?

Stefan

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