Multilingual Templates and Modules

Intro
This project describes how templates and modules can be kept in sync between multiple languages and projects.

Why is this needed? Because we do not have a single Wikipedia, we have 300 separate Wikipedias plus many other projects, and every time someone creates a good new template or a Lua module, it has to be copied 300+ times. More importantly, each template has to be translated 300 times, which is often very difficult, in part because one has to thoroughly understand MediaWiki markup, and also because often authors assume templates will be used for just one language. Plus templates depend on other templates. Plus once copied, templates are often improved, and each copy has to be updated. The pure human expense of copying templates and modules is such, that most templates are either never copied or never updated, especially for the smaller wikis.

Is this the best approach? No, but it is the most reasonable approach under the circumstances that can be easily adapted for a different technology. A very significant MediaWiki rewrite is required to make this possible on the system level. This functionality has been requested from the start 18 years ago, but not much was done simply because this is a very hard problem to solve. With this approach it is possible to create multilingual content now, and once MediaWiki supports it, we can easily migrate this content to the new system without much work.

Method

 * DiBabel bot will copy templates and modules from mediawiki.org to all other sites/languages listed in Wikidata for that page, without any modifications.
 * It will be copied ONLY if Wikidata item has "instance of" set to (Q63090714).
 * It will be copied ONLY if the current content of the page exists in the history of mediawiki.org's (origin) version. E.g. if a user modifies English version of the page, it will not be overwritten unless that exact text ever existed in the history of the page on mediawiki.org.  To resume automatic synchronization, a user must copy the latest version of the page from mediawiki.org. Note that simply reverting a page to an older version will not be enough to prevent a bot from copying it again. A page has to be different from any of origin's revisions (e.g. add a note why the page was modified).
 * Any template names will be automatically localized inside the wiki markup, e.g. text will become , as long as Template:MW name exists on mediawiki.org, and it has a corresponding template on the destination wiki. Shared templates should not use non-shared templates, as that may cause unexpected results.

Translating Content
There is very little value in having non-translated content copied as is. The Module:TNT was created specifically to solve that. Instead of storing English text in a module or a template, TNT allows them to be designed language-neutral, and store multilingual text in the tabular data pages on Commons. This way your module or template will use those translated strings (messages), or if the message has not yet been translated, will fallback to English. When someone updates the translation table, your page will automatically update (might take some time, or you can purge it), but no change in the template or module is needed on any of the wikis. This process is very similar to MediaWiki's localisation, and supports all standard localization conventions such as NaN undefineds and other parameters.

For a simple example, see Data:I18n/Template:Graphs.tab - a table with two messages, each message having a single parameter. By convention, all translation pages should have  Data:I18n/...  prefix to separate them from other types of data.

Global Modules
Just like templates, modules should also use TNT module for localization. TODO: lua example

Translating Template Parameters
Template parameters are usually stored as a JSON templatedata block inside the template's /doc subpage. This makes it convenient to translate, but when a new parameter is added to a global template, all /doc pages need to be updated in every language. TNT helps with this by automatically generating the templatedata block from a table stored on Commons. Placing this line into every /doc sub-page will use Data:Templatedata/Graph:Lines.tab table to generate all the needed templatedata information in every language. Even if the local community has not translated the full template documentation, they will be able to see all template parameters, centrally updated.