🐛 FIX: Fix translation for prev/next

[choldgraf]

This uses lowercase previous and next entries, which is the reason that Sphinx wasn't translating them before. Also reverts back to the _( translation text since that's the Sphinx standard.

It also sets previous/next to lowercase so they take up less visual attention, per @pfelber's comments

may address #359 if others confirm

[choldgraf]

Merging this in so that others can give this a shot

[chrisjsewell]

Also reverts back to the _( translation text since that's the Sphinx standard.

if this works then that is absolutely fine, but I would note that this is not sphinx’s standard for extensions, it is the internal standard for their own documentation and I think not really meant for external use. This is because it is not possible for extensions to extend the available translations (happy to be corrected though)

[choldgraf]

@chrisjsewell yeah I was trying to figure this out as well. Here I took some inspiration from @jpmckinney who was adding i18n support to the pydata theme in https://github.com/pydata/pydata-sphinx-theme/pull/399/files

In that PR he's just using the _( (which I learned is not actually a Sphinx short-hand, it's a jinja shorthand

[chrisjsewell]

@choldgraf so basically this is the full explanation:

• sphinx loads the jinja translator here: https://github.com/sphinx-doc/sphinx/blob/f127a2ff5d6d86918a5d3ac975e8ab8a24c407d1/sphinx/util/template.py#L31
• it generates this translation function here: https://github.com/sphinx-doc/sphinx/blob/f127a2ff5d6d86918a5d3ac975e8ab8a24c407d1/sphinx/locale/__init__.py#L202
  • this defaults to sphinx's internal translation catalog
• Here I add to sphinx the sphinx-book-theme translation catalog:

  sphinx-book-theme/sphinx_book_theme/__init__.py

  Line 288 in 613e665

  app.add_message_catalog(MESSAGE_CATALOG_NAME, locale_dir)

• Here I generate the translation function for this catalog, then add it to the jinja context (as translate):

  sphinx-book-theme/sphinx_book_theme/__init__.py

  Line 194 in 613e665

  translation = get_translation(MESSAGE_CATALOG_NAME)

[choldgraf]

right - maybe this only works because we are just re-using translations for words that are already in the Sphinx catalog ("page" and "next" and "previous")? Either way this is a helpful write-up, I've added it to #382 !

[chrisjsewell]

maybe this only works because we are just re-using translations for words that are already in the Sphinx catalog ("page" and "next" and "previous")?

yep thats exactly the case; anything you can find in one of their translation files you could use with _(, e.g. https://github.com/sphinx-doc/sphinx/blob/f127a2ff5d6d86918a5d3ac975e8ab8a24c407d1/sphinx/locale/en_FR/LC_MESSAGES/sphinx.po

But obviously it is better if we are consistent in using our own translation files (and thus the translate function)