Create localized versions of the templates and template parts

[bobbingwide]

Full Site Editing themes should support internationalization (i18n) and localization (l10n).

The process to extract and localize is summarized by this diagram.

Requirements

• To be able to use the Fizzie theme in the user's selected locale.
• To automatically extract and localize templates and template parts.
• Test with two additional languages:

1. UK English - locale en_GB
2. bbboing's language bb_BB

Proposed solution

• Create localized versions of the templates and template parts delivered by Fizzie.
• Use the automated tools developed in FSE - Can we internationalize .html files without requiring any special markup? oik-i18n#7
• Use a batch routine t10n.bat to automate the translation into UK English and bbboing.
• Update Gutenberg and/or Fizzie to support loading of translated templates and template parts
• Test for UK English ( en_GB ) and bbboing ( bb_BB ).

Requirements on Gutenberg

• Gutenberg's template and template loading logic needs to be updated to take into account the user's locale.
• The translated files will be stored in subfolders of the languages folder, with one directory per supported locale.
• If the directory isn't present the US English files are used.

Assumptions, scope, exclusions and caveats

• Templates and template parts are inherently static; they don't implement conditional / looping logic.
• Internationalization (i18n) of the templates and template parts is only necessary for certain strings which should not be translated.
• As such, localized versions can be created at build time, or whenever the translations are updated.
• Blocks used in templates and template parts may implement conditional / looping logic.
• These blocks are usually server side rendered using PHP.
• A theme's PHP code will be localized using makepot.
• Any JavaScript blocks delivered by the theme will be localized using makejson.
• The solution should support all locales and character sets currently supported by WordPress.
• The solution should support themes which are not delivered from wordpress.org

Limitations of the prototyped solution

• t10n.bat is currently dependent upon oik-batch's oik
• The current routines are prototyped batch routines which echo debug information.
• Not all scenarios are yet catered for by the routines invoked by t10n.
• The current solution doesn't merge .pot files into one file prior to translation.
• But text strings used in PHP and template files and parts are not expected to be the same.
• So there shouldn't be too many duplicate strings to translate.

[bobbingwide]

I've created a new version of the extraction and localization routines in bobbingwide/oik-i18n/issues/9 which now supports extraction translation and localization of rich text strings. These changes need to be tested in Fizzie before the Gutenberg proposal is updated.

[bobbingwide]

t10n needs to be updated to work with a different directory structure.

[bobbingwide]

Having updated t10n I was able to re-activate the template part override to demonstrate the loading of localized template parts on the front end.

I can't remember whether or not I managed to achieve loading of localized templates but I've found a note that suggests I didn't bother. It says

We can implement a local solution for the Fizzie theme that doesn't require changes to Gutenberg with the following assumptions.

• The block-template files only contain non-translatable content

bobbingwide/oik-i18n#7 (comment)

[bobbingwide]

The current logic for overriding template parts doesn't work for template parts that are created in the Site Editor or Post Editor.
On the front end it displays a message saying that the language file couldn't be found.
The logic doesn't try to locate the post for the template part.