Internationalization
====================
cinder uses `gettext <http://docs.python.org/library/gettext.html>`_ so that
user-facing strings such as log messages appear in the appropriate
language in different locales.

To use gettext, make sure that the strings passed to the logger are wrapped
in a ``_()`` function call. For example::

    LOG.debug(_("block_device_mapping %s"), block_device_mapping)

If you have multiple arguments, the convention is to use named parameters.
It's common to use the ``locals()`` dict (which contains the names and values
of the local variables in the current scope) to do the string interpolation.
For example::

    label = ...
    sr_ref = ...
    LOG.debug(_('Introduced %(label)s as %(sr_ref)s.') % locals())

If you do not follow the project conventions, your code may cause the
LocalizationTestCase.test_multiple_positional_format_placeholders test to fail
in cinder/tests/test_localization.py.

The ``_()`` function is brought into the global scope by doing::

    from cinder.openstack.common import gettextutils
    gettextutils.install("cinder")

These lines are needed in any toplevel script before any cinder modules are
imported. If this code is missing, it may result in an error that looks like::

    NameError: name '_' is not defined