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1 .. -*- mode: rst; encoding: utf-8 -*-
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2
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3 =============================
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4 Support Classes and Functions
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5 =============================
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6
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7 .. contents:: Contents
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8 :depth: 2
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9 .. sectnum::
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10
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11
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12 The ``babel.support`` modules contains a number of classes and functions that
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13 can help with integrating Babel, and internationalization in general, into your
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14 application or framework. The code in this module is not used by Babel itself,
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15 but instead is provided to address common requirements of applications that
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16 should handle internationalization.
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17
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18
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19 ---------------
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20 Lazy Evaluation
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21 ---------------
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22
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23 One such requirement is lazy evaluation of translations. Many web-based
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24 applications define some localizable message at the module level, or in general
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25 at some level where the locale of the remote user is not yet known. For such
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26 cases, web frameworks generally provide a "lazy" variant of the ``gettext``
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27 functions, which basically translates the message not when the ``gettext``
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28 function is invoked, but when the string is accessed in some manner.
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29
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30
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31 ---------------------------
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32 Extended Translations Class
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33 ---------------------------
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34
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35 Many web-based applications are composed of a variety of different components
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36 (possibly using some kind of plugin system), and some of those components may
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37 provide their own message catalogs that need to be integrated into the larger
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38 system.
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39
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40 To support this usage pattern, Babel provides a ``Translations`` class that is
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41 derived from the ``GNUTranslations`` class in the ``gettext`` module. This
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42 class adds a ``merge()`` method that takes another ``Translations`` instance,
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43 and merges the content of the latter into the main catalog:
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44
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45 .. code-block:: python
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46
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47 translations = Translations.load('main')
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48 translations.merge(Translations.load('plugin1'))
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