cmlenz@115: .. -*- mode: rst; encoding: utf-8 -*-
cmlenz@115: 
cmlenz@115: ============
cmlenz@115: Introduction
cmlenz@115: ============
cmlenz@115: 
cmlenz@115: The functionality Babel provides for internationalization (I18n) and
cmlenz@115: localization (L10N) can be separated into two different aspects:
cmlenz@115: 
cmlenz@115:  * tools to build and work with ``gettext`` message catalogs, and
cmlenz@115:  * a Python interface to the CLDR (Common Locale Data Repository), providing
cmlenz@115:    access to various locale display names, localized number and date
cmlenz@115:    formatting, etc.
cmlenz@115: 
cmlenz@115: .. contents:: Contents
cmlenz@115:    :depth: 2
cmlenz@115: .. sectnum::
cmlenz@115: 
cmlenz@115: 
cmlenz@115: Message Catalogs
cmlenz@115: ================
cmlenz@115: 
cmlenz@115: While the Python standard library includes a
cmlenz@115: `gettext <http://docs.python.org/lib/module-gettext.html>`_ module that enables
cmlenz@115: applications to use message catalogs, it requires developers to build these
cmlenz@115: catalogs using GNU tools such as ``xgettext``, ``msgmerge``, and ``msgfmt``.
cmlenz@115: And while ``xgettext`` does have support for extracting messages from Python
cmlenz@115: files, it does not know how to deal with other kinds of files commonly found
cmlenz@115: in Python web-applications, such as templates, nor does it provide an easy
cmlenz@115: extensibility mechanism to add such support.
cmlenz@115: 
cmlenz@115: Babel addresses this by providing a framework where various extraction methods
cmlenz@115: can be plugged in to a larger message extraction framework, and also removes
cmlenz@115: the dependency on the GNU ``gettext`` tools for common tasks, as these aren't
cmlenz@115: necessarily available on all platforms. See `Working with Message Catalogs`_
cmlenz@115: for details on this aspect of Babel.
cmlenz@115: 
cmlenz@124: .. _`Working with Message Catalogs`: messages.html
cmlenz@115: 
cmlenz@115: 
cmlenz@115: Locale Data
cmlenz@115: ===========
cmlenz@115: 
cmlenz@115: Furthermore, while the Python standard library does include support for basic
cmlenz@115: localization with respect to the formatting of numbers and dates (the
cmlenz@115: `locale <http://docs.python.org/lib/module-locale.html>`_ module, among others),
cmlenz@115: this support is based on the assumption that there will be only one specific
cmlenz@115: locale used per process (at least simultaneously.) Also, it doesn't provide
cmlenz@115: access to other kinds of locale data, such as the localized names of countries,
cmlenz@115: languages, or time-zones, which are frequently needed in web-based applications.
cmlenz@115: 
cmlenz@115: For these requirements, Babel includes data extracted from the `Common Locale
cmlenz@115: Data Repository (CLDR) <http://unicode.org/cldr/>`_, and provides a number of
cmlenz@115: convenient methods for accessing and using this data. See `Locale Display
cmlenz@133: Names`_, `Date Formatting`_, and `Number Formatting`_ for more information on
cmlenz@133: this aspect of Babel.
cmlenz@115: 
cmlenz@115: 
cmlenz@115: .. _`Locale Display Names`: display.html
cmlenz@124: .. _`Date Formatting`: dates.html
cmlenz@124: .. _`Number Formatting`: numbers.html