Open Stack

> So, write:
>
>     LOG.debug(u'Could not do whatever you asked: %s', exc)
>
> or just:
>
>     LOG.debug(exc)

Actually, that's a bad idea to pass an exception instance to
some log function: LOG.debug(exc). Let me show you why.

Here a snippet from logging.py:

    def getMessage(self):
        if not _unicode:
            msg = str(self.msg)
        else:
            msg = self.msg
            if not isinstance(msg, basestring):
                try:
                    msg = str(self.msg)
                except UnicodeError:
                    msg = self.msg  # we keep exception object as it is
        if self.args:               # this condition is obviously False
            msg = msg % self.args
        return msg                  # returns an exception object, not a
text

And here another snippet from the format() method:

    record.message = record.getMessage()
    # ... some time formatting ...
    s = self._fmt % record.__dict__ # FAIL

the old string formatting will call str(), not unicode() and we will FAIL
with UnicodeEncodeError.



On Wed, May 21, 2014 at 6:38 PM, Doug Hellmann
<doug.hellmann at dreamhost.com>wrote:

> On Thu, May 15, 2014 at 11:29 AM, Victor Stinner
> <victor.stinner at enovance.com> wrote:
> > Hi,
> >
> > I'm trying to define some rules to port OpenStack code to Python 3. I
> just
> > added a section in the "Port Python 2 code to Python 3" about formatting
> > exceptions and the logging module:
> >
> https://wiki.openstack.org/wiki/Python3#logging_module_and_format_exceptions
> >
> > The problem is that I don't know what is the best syntax to log
> exceptions.
> > Some projects convert the exception to Unicode, others use str(). I also
> saw
> > six.u(str(exc)) which is wrong IMO (it can raise unicode error if the
> message
> > contains a non-ASCII character).
> >
> > IMO the safest option is to use str(exc). For example, use
> > LOG.debug(str(exc)).
> >
> > Is there a reason to log the exception as Unicode on Python 2?
>
> Exception classes that define translatable strings may end up with
> unicode characters that can't be converted to the default encoding
> when str() is called. It's better to let the logging code handle the
> conversion from an exception object to a string, since the logging
> code knows how to deal with unicode properly.
>
> So, write:
>
>     LOG.debug(u'Could not do whatever you asked: %s', exc)
>
> or just:
>
>     LOG.debug(exc)
>
> instead of converting explicitly.
>
> Doug
>
> >
> > Victor
> >
> > _______________________________________________
> > OpenStack-dev mailing list
> > OpenStack-dev at lists.openstack.org
> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
> _______________________________________________
> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
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