docs: add missing environment defaults

[lockejan]

The actual environment.defaults differ from the documented ones on the options-page.

I don't have a real preference between removing the defaults to align with the docs or updating the docs to align with the defaults. The least amount of change was to keep them, so I just did the latter.

~~Besides that, there are even more undocumented defaults, namely XDG_CONFIG_DIRS and XDG_DATA_DIRS, see https://github.com/LnL7/nix-darwin/blob/44da835ac40dab5fd231298b59d83487382d2fab/modules/environment/default.nix#L173-L176 I'm not sure how to go about them, but as such are not static I'd rather omit them at this point.~~

closes #395

[lockejan]

after learning about defaultText, I wonder if this should be the preferred way to present it? @malob

[malob]

This is something I've often been a little annoyed by with modules in the Nix ecosystem. Where the particular annoyance is that there are some, what I'll call, core options (like environment.variables, that are set to values "by default" in the module they are declared in (and sometimes in other modules as well) to some value (i.e, before the user adds their on modules with additional configuration they will always have the same predictable values), and the only reliable way to figure out what their "default" will be is to look rummage through the code base and figure it out.

I think something like the suggested change here is likely an improvement. My main concern would be that it's kind of brittle, in that, if a change is made to nix-darwin that would add something extra to environment.variables "by default", the person making the change (or a reviewer) would have to notice this and update the defaultText for the option accordingly. In this world it seems like it's only a matter of time before someone makes a change and that latter step is missed, resulting in defaultText no longer accurately representing the "default" value of the option.

I'm currently leaning towards thinking that adding defaultText with the risk it becoming inaccurate at some point is still better than the status quo, where it's obviously wrong, but I'm not confident about that. I expect peoples intuitions here to vary.

[lockejan]

Can we merge @LnL7 or @domenkozar ?

[domenkozar]

I'd add a comment at both locations that there's another place to update the values.

[lockejan]

I'd add a comment at both locations that there's another place to update the values.

I'm not sure if I understood you correctly. Does my last commit aligns with what you were referring to? @domenkozar

[domenkozar]

Yeah, but I'd say something like WARNING: XDG vars are also set up in this file above

[lockejan]

Yeah, but I'd say something like WARNING: XDG vars are also set up in this file above

Sorry for the ping-pong, but maybe there's a misunderstanding here or I'm just confused about the motivation for your request. 🙈😄

Just to be clear here, my initial additions are only documentation and aren't changing any behaviour. The entries in XDG vars are the result of concatenating "/etc/xdg" and "/share" to each entry in NIX_PROFILES which are defined under environment.profile in the same file.

There is currently no other place where XDG vars are set. That been said, can you please give me some more context why you think an additional comment is necessary?

[domenkozar]

I took a proper look at this one, why don't we just set the correct default?

[lockejan]

I took a proper look at this one, why don't we just set the correct default?

That was my initial idea as well. However, after asking around in #macos:nixos.org, people noted that those are generated values, which made me change it to the exact expressions. I'm fine with having exact values instead, like this:

XDG_CONFIG_DIRS=$HOME/.nix-profile/etc/xdg:/run/current-system/sw/etc/xdg:/nix/var/nix/profiles/default/etc/xdg
XDG_DATA_DIRS=$HOME/.nix-profile/share:/run/current-system/sw/share:/nix/var/nix/profiles/default/share

[lockejan]

Replaced the expression with the actual result. This way it's clear what is being set, as long as the list in environment.profile doesn't change.

[lockejan]

How about merging this @domenkozar ? (:

[LnL7]

I'm not sure if hardcoding the defaults is a great idea, actually evaluating the defaults with something like darwin-option instead would ensure things stay in sync. The current implementation doesn't interpet the mkDefault values correctly however.

$ darwin-option environment.variables
Value:
{ EDITOR = "nano"; NIX_PATH = "darwin-config=$HOME/.nixpkgs/darwin-configuration.nix:/nix/var/nix/profiles/per-user/root/channels"; NIX_SSL_CERT_FILE = "/etc/ssl/certs/ca-certificates.crt"; PAGER = "less -R"; TERMINFO_DIRS = "$HOME/.nix-profile/share/terminfo:/run/current-system/sw/share/terminfo:/nix/var/nix/profiles/default/share/terminfo:/usr/share/terminfo"; XDG_CONFIG_DIRS = "$HOME/.nix-profile/etc/xdg:/run/current-system/sw/etc/xdg:/nix/var/nix/profiles/default/etc/xdg"; XDG_DATA_DIRS = "$HOME/.nix-profile/share:/run/current-system/sw/share:/nix/var/nix/profiles/default/share"; }

Default:
{ }

[emilazy]

AFAIK it's not possible for option documentation to depend on a build (without full-on IFD) so I'm not sure that's practical.