renderCompat syntax is ugly :-(
And it don't work for me:
res.renderCompat!("sellingnewcreated.dt", typeid(req), req, typeid(a), a) // line 38
(Variant(req), Variant(a)); // line 39
source/app.d(39): Error: variable req cannot be read at compile time
source/app.d(39): Error: variable a cannot be read at compile time
May be you can write mixin or template wrapper for renderCompat?