Thank you. What I want to do is override a few fields by default in the pom, add another file, add add some text in the README. I think the data-fn lets me handle the first, not sure about the rest

In theory, the template-fn would let you read some existing files, write modified versions to a temporary location, and return an updated template.edn data structure that would point to those new temporary files. I don't know that anyone has actually tried that yet... but if you run into limitations/bugs trying to do it, create issues and I'll address them because that is supposed to work.

(side note: if you do that in the next two weeks, don't expect quick responses -- I'll be traveling and mostly off the grid, but will address them when I return... just to set expectations)

no problem. I think a slightly more general feature which could be cool is "derivative templates"

Instead of writing a template from scratch or doing back flips with temporary files, to be able to define a template as a variation on another template, sort of like immutable hash maps

Yup. That does sound like a nice enhancement. No idea how that might work (given the infrastructure on which deps-new is built) but feel free to create an issue with some brainstorming ideas if you have them...

https://github.com/seancorfield/deps-new/issues/27

Hey Sean, checking in if there's been any progress on this front

Nope. Waiting for folks to propose something since this isn't a problem I have so I don't know what a solution should look like.