Yes, that would be useful. Basically, what you have in https://github.com/infogulch/caddy-xtemplate/blob/master/tem... - but without Caddy dependencies and with a way to use any router library (I use gorilla/mux).

I would make the templates library take a callback function for every public template: func(method, path string, template).

Then the user could add any custom logic to register the route handler and execute the template with any application specific inputs.

I'll have to think about that. It currently uses path parameters from the julienschmidt/httprouter router implementation, which I think are pretty important. How would you expect to define and receive path parameters?

gorilla/mux supports parameters in the path as well. For example: "/posts/{id:[0-9]+}"

Passing the parameters from the handler to the template could be left to the user of the library.