How to extend lib

[Lykos153]

Hey :)

I have a flake with various perSystem modules in their own files. Many of them need access to a custom implementation of mkRenamedOptionModule. The only way I found to do this is:

{lib, ...}: {
  mylib = import ../../../nix/module/lib.nix {inherit lib;};
  imports = [ (mylib.mkRenamedOptionModule ["a"] ["b"])];
}

Which is kind of ugly because in each file I need to get the relative path to lib.nix right and moving them is a nightmare.

I came across config._module.args.mylib = ... in #222 but I can't use that in imports because that would cause an infinite recursion.

So what I'm looking for is a way to add my function to lib, eg. at lib.mylib.mkRenamedOptionModule so that all modules have access to them by default. How can I achieve this?

[srid]

FWIW, I did some exploration on this here.

[roberth]

Hello Silvio,
Nothing is impossible, but I don't recommend literally extending lib because as a general pattern it's not good for reusability. If you or others do this often, you're effectively creating one or many little dialects that prevents reuse of your modules, without much visual indication in the module that there could be problems.
So what I would recommend instead is to use specialArgs (it's a mkFlake argument too) to put your own library under a recognizable name that isn't lib.