Home Original page

unpickling derived LogRecord in python 2.7 from python2.6

Peter Otten __peter__ at web.de
Thu Apr 28 03:22:06 EDT 2011 
Vinay Sajip wrote:

> On Apr 27, 5:41 pm, Peter Otten <__pete... at web.de> wrote:
> 
>> The Problem is that as of Python 2.7logging.LogRecord has become a
>> newstyle class which is pickled/unpickled differently. I don't know if
>> there is an official way to do the conversion, but here's what I've
>> hacked up. The script can read pickles written with 2.6 in 2.7, but not
>> the other way round.
>> [code snipped]
> 
> I don't know about "official", but another way of doing this is to
> pickle just the LogRecord's __dict__ and send that over the wire. The
> logging package contains a function makeLogRecord(d) where d is a
> dict.

You are right, my approach is too complicated and only needed when the OP 
cannot modify the sending script -- which is unlikely.

> This is the approach used by the examples in the library documentation
> which pickle events for sending across a network:
> 
> http://docs.python.org/howto/logging-cookbook.html#sending-and-receiving-
logging-events-across-a-network
> 
> The built-in SocketHandler pickles the LogRecord's __dict__ rather
> than the LogRecord itself, precisely because of the improved
> interoperability over pickling the instance directly.

As a minimal change ensuring that the logging.LogRecord subclass used by the 
OP is a newstyle class in 2.6 with

class LogRecord(logging.LogRecord, object):
    #...

should work, too.
More information about the Python-list mailing list