Kaldari, RobLa, Trevor and I met yesterday to discuss the template RFC [1].
Sadly Gabriel was not present. Kaldari and I are very concerned that we are blocking standardisation of a generic template library on the completion of Knockoff.
Trevor, Kaldari and I identified that two things need to happen for the templating solution that currently lives in Mantle [2] to core:
1) We need some JavaScript API for using templates (in current form all we have is a standard way to ship templates from the server to the frontend). Trevor is working on a template widget for oojs which will make this possible 2) We need a standard template language 3) Better namespacing for templates - we identified that we will need to find better ways of uniquely identifying templates [3].
We questioned whether point 2 should be blocking, as we recognised that even if we decide to standardise on Knockoff in future, it should be trivial to write a script that converts Hogan/Handlebars template language to Knockoff. The Mantle ResourceLoader module in current form is template agnostic and currently works with both Hogan and Handlebars, so in theory should make it easy to transition from one template language to another.
On this basis, I think the next step would be for the oojs development team to get a template widget up that can be used by Mantle.
[1] https://www.mediawiki.org/wiki/Requests_for_comment/HTML_templating_library [2] https://www.mediawiki.org/wiki/Extension:Mantle [3] https://bugzilla.wikimedia.org/show_bug.cgi?id=69916