[openstack-dev] [OpenStack-Dev] Logging formats and i18n

Ben Nemec openstack at nemebean.com
Mon Dec 22 17:03:10 UTC 2014

On 12/22/2014 09:42 AM, John Griffith wrote:
> Lately (on the Cinder team at least) there's been a lot of
> disagreement in reviews regarding the proper way to do LOG messages
> correctly.  Use of '%' vs ',' in the formatting of variables etc.
> We do have the oslo i18n guidelines page here [1], which helps a lot
> but there's some disagreement on a specific case here.  Do we have a
> set answer on:
> LOG.info(_LI('some message: v1=%(v1)s v2=%(v2)s') % {'v1': v1, 'v2': v2})
> vs
> LOG.info(_LI('some message: v1=%(v1)s v2=%(v2)s'), {'v1': v1, 'v2': v2})

This is the preferred way.

Note that this is just a multi-variable variation on
and the reasoning discussed there applies.

I'd be curious why some people prefer the % version because to my
knowledge that's not recommended even for untranslated log messages.

> It's always fun when one person provides a -1 for the first usage; the
> submitter changes it and another reviewer gives a -1 and says, no it
> should be the other way.
> I'm hoping maybe somebody on the olso team can provide an
> authoritative answer and we can then update the example page
> referenced in [1] to clarify this particular case.
> Thanks,
> John
> [1]: http://docs.openstack.org/developer/oslo.i18n/guidelines.html
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