i18n API

sphinx.locale.init(locale_dirs: Iterable[str | os.PathLike[str] | None], language: str | None, catalog: str = 'sphinx', namespace: str = 'general') → tuple[NullTranslations, bool][source]

Look for message catalogs in locale_dirs and ensure that there is at least a NullTranslations catalog set in translators. If called multiple times or if several .mo files are found, their contents are merged together (thus making init reentrant).

sphinx.locale.init_console(locale_dir: str | os.PathLike[str] | None = None, catalog: str = 'sphinx') → tuple[NullTranslations, bool][source]

Initialize locale for console.

Added in version 1.8.

sphinx.locale.get_translation(catalog: str, namespace: str = 'general') → Callable[[str], str][source]

Get a translation function based on the catalog and namespace.

The extension can use this API to translate the messages on the extension:

from pathlib import Path
from sphinx.locale import get_translation

MESSAGE_CATALOG_NAME = 'myextension'  # name of *.pot, *.po and *.mo files
_ = get_translation(MESSAGE_CATALOG_NAME)
text = _('Hello Sphinx!')


def setup(app):
    package_dir = Path(__file__).resolve().parent
    locale_dir = package_dir / 'locales'
    app.add_message_catalog(MESSAGE_CATALOG_NAME, locale_dir)

With this code, sphinx searches a message catalog from ${package_dir}/locales/${language}/LC_MESSAGES/myextension.mo. The language is used for the searching.

Added in version 1.8.

sphinx.locale._(message: str) → str

Translation function for messages on documentation (menu, labels, themes and so on). This function follows language setting.

sphinx.locale.__(message: str) → str

Translation function for console messages This function follows locale setting (LC_ALL, LC_MESSAGES and so on).

Extension internationalization (i18n) and localization (l10n) using i18n API

Added in version 1.8.

An extension may naturally come with message translations. This is briefly summarized in sphinx.locale.get_translation() help.

In practice, you have to:

  1. Choose a name for your message catalog, which must be unique. Usually the name of your extension is used for the name of message catalog.

  2. Mark in your extension sources all messages as translatable, via sphinx.locale.get_translation() function, usually renamed _(), e.g.:

    src/__init__.py
    from sphinx.locale import get_translation

MESSAGE_CATALOG_NAME = 'myextension'
_ = get_translation(MESSAGE_CATALOG_NAME)

translated_text = _('Hello Sphinx!')

  3. Set up your extension to be aware of its dedicated translations:

    src/__init__.py
    def setup(app):
    package_dir = Path(__file__).resolve().parent
    locale_dir = package_dir / 'locales'
    app.add_message_catalog(MESSAGE_CATALOG_NAME, locale_dir)

  4. Generate message catalog template *.pot file, usually in locale/ source directory, for example via Babel:

    $ pybabel extract --output=src/locale/myextension.pot src/

  5. Create message catalogs (*.po) for each language which your extension will provide localization, for example via Babel:

    $ pybabel init --input-file=src/locale/myextension.pot --domain=myextension --output-dir=src/locale --locale=fr_FR

  6. Translate message catalogs for each language manually

  7. Compile message catalogs into *.mo files, for example via Babel:

    $ pybabel compile --directory=src/locale --domain=myextension

  8. Ensure that message catalog files are distributed when your package will be installed, by adding equivalent line in your extension MANIFEST.in:

    MANIFEST.in
    recursive-include src *.pot *.po *.mo

When the messages on your extension has been changed, you need to also update message catalog template and message catalogs, for example via Babel:

$ pybabel extract --output=src/locale/myextension.pot src/
$ pybabel update --input-file=src/locale/myextension.pot --domain=myextension --output-dir=src/locale