cmlenz@117: .. -*- mode: rst; encoding: utf-8 -*-
cmlenz@117: 
cmlenz@117: ============
cmlenz@117: Introduction
cmlenz@117: ============
cmlenz@117: 
cmlenz@117: The functionality Babel provides for internationalization (I18n) and
cmlenz@117: localization (L10N) can be separated into two different aspects:
cmlenz@117: 
cmlenz@117:  * tools to build and work with ``gettext`` message catalogs, and
cmlenz@117:  * a Python interface to the CLDR (Common Locale Data Repository), providing
cmlenz@117:    access to various locale display names, localized number and date
cmlenz@117:    formatting, etc.
cmlenz@117: 
cmlenz@117: .. contents:: Contents
cmlenz@117:    :depth: 2
cmlenz@117: .. sectnum::
cmlenz@117: 
cmlenz@117: 
cmlenz@117: Message Catalogs
cmlenz@117: ================
cmlenz@117: 
cmlenz@117: While the Python standard library includes a
cmlenz@117: `gettext <http://docs.python.org/lib/module-gettext.html>`_ module that enables
cmlenz@117: applications to use message catalogs, it requires developers to build these
cmlenz@117: catalogs using GNU tools such as ``xgettext``, ``msgmerge``, and ``msgfmt``.
cmlenz@117: And while ``xgettext`` does have support for extracting messages from Python
cmlenz@117: files, it does not know how to deal with other kinds of files commonly found
cmlenz@117: in Python web-applications, such as templates, nor does it provide an easy
cmlenz@117: extensibility mechanism to add such support.
cmlenz@117: 
cmlenz@117: Babel addresses this by providing a framework where various extraction methods
cmlenz@117: can be plugged in to a larger message extraction framework, and also removes
cmlenz@117: the dependency on the GNU ``gettext`` tools for common tasks, as these aren't
cmlenz@117: necessarily available on all platforms. See `Working with Message Catalogs`_
cmlenz@117: for details on this aspect of Babel.
cmlenz@117: 
cmlenz@126: .. _`Working with Message Catalogs`: messages.html
cmlenz@117: 
cmlenz@117: 
cmlenz@117: Locale Data
cmlenz@117: ===========
cmlenz@117: 
cmlenz@117: Furthermore, while the Python standard library does include support for basic
cmlenz@117: localization with respect to the formatting of numbers and dates (the
cmlenz@117: `locale <http://docs.python.org/lib/module-locale.html>`_ module, among others),
cmlenz@117: this support is based on the assumption that there will be only one specific
cmlenz@117: locale used per process (at least simultaneously.) Also, it doesn't provide
cmlenz@117: access to other kinds of locale data, such as the localized names of countries,
cmlenz@117: languages, or time-zones, which are frequently needed in web-based applications.
cmlenz@117: 
cmlenz@117: For these requirements, Babel includes data extracted from the `Common Locale
cmlenz@117: Data Repository (CLDR) <http://unicode.org/cldr/>`_, and provides a number of
cmlenz@117: convenient methods for accessing and using this data. See `Locale Display
cmlenz@135: Names`_, `Date Formatting`_, and `Number Formatting`_ for more information on
cmlenz@135: this aspect of Babel.
cmlenz@117: 
cmlenz@117: 
cmlenz@117: .. _`Locale Display Names`: display.html
cmlenz@126: .. _`Date Formatting`: dates.html
cmlenz@126: .. _`Number Formatting`: numbers.html