2dce8c92f6
Using of locals() for formatting string is a nasty thing because: 1) It is not so clear as using explicit dicts 2) It could produce hidden errors during refactoring 3) Changing name of variable causes change in message 4) Creating a lot of unused variables fixes bug 1171936 Change-Id: I293d7ebb875f65cce322d4938d1ae323f3aded8d
35 lines
1.4 KiB
ReStructuredText
35 lines
1.4 KiB
ReStructuredText
Internationalization
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====================
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nova uses `gettext <http://docs.python.org/library/gettext.html>`_ so that
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user-facing strings such as log messages appear in the appropriate
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language in different locales.
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To use gettext, make sure that the strings passed to the logger are wrapped
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in a ``_()`` function call. For example::
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LOG.debug(_("block_device_mapping %s"), block_device_mapping)
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Do not use ``locals()`` for formatting messages because:
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1. It is not as clear as using explicit dicts.
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2. It could produce hidden errors during refactoring.
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3. Changing the name of a variable causes a change in the message.
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4. It creates a lot of otherwise unused variables.
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If you do not follow the project conventions, your code may cause the
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LocalizationTestCase.test_multiple_positional_format_placeholders test to fail
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in nova/tests/test_localization.py.
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The ``_()`` function is brought into the global scope by doing::
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from nova.openstack.common import gettextutils
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gettextutils.install('nova')
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These lines are needed in any toplevel script before any nova modules are
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imported. If this code is missing, it may result in an error that looks like::
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NameError: name '_' is not defined
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The gettextutils.install() function also queries the NOVA_LOCALEDIR environment
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variable to allow overriding the default localedir with a specific custom
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location for Nova's message catalog.
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