How to create class/module like structures in a home-manager config?

[jackerschott]

I was wondering how home-manager is intended in the following situation: I want e.g. my editor config to be agnostic to which specific editor I use. Let's say e.g. I want to use neovim on one machine and emacs on another machine. But I want to be able to have a shortcut in my desktop environment that opens an obsidian vault in the active text editor, so I want something like editor.obsidian.buildVaultOpenCommand that takes the name of the vault as a string and returns a command string that I can execute in a script. But possibly I also want something like editor.buildFileOpenCommand that works similarly. Now I tried to implement this with _module.args, such that I have an editor attribute set that I can access globally, but I can't specify _module.args.editor both in my editor/neovim/default.nix and my editor/neovim/plugins/obsidian.nix which would be the canonical way to do it (since the default.nix should not know about the details of the obsidian config), since apparently they don't get merged automatically? And if I use lib.mkDefault in my neovim default.nix, the editor.buildFileOpenCommand just gets overriden, because it's not in the _module.args.editor from the obsidian.nix.

Long story short: I'm not sure if that is the intended usecase for _module.args. If yes, than this would be a bug report / feature request I guess. But if not, then how can I do something like this? I.e. how can you create a module/class like structure that one is used from other programming languages like C/Rust/Python/etc., i.e. something I can import and use functions from. In pure nix, I would imagine this can be achieved by having a special attribute like _functions in every attribute set that I write some part of the config in, that get's ignored for the configuration, but that I can use in other parts of the config, which I guess is exactly what _module.args can achieve theoretically?