mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-11-01 23:22:37 +00:00
38 lines
835 B
Nix
38 lines
835 B
Nix
{ config, pkgs, ... }:
|
|
|
|
with pkgs.lib;
|
|
|
|
let
|
|
|
|
failed = map (x: x.message) (filter (x: !x.assertion) config.assertions);
|
|
|
|
in
|
|
|
|
{
|
|
|
|
options = {
|
|
|
|
assertions = mkOption {
|
|
default = [];
|
|
example = [ { assertion = false; msg = "you can't enable this for that reason"; } ];
|
|
merge = pkgs.lib.mergeListOption;
|
|
description = ''
|
|
This option allows modules to express conditions that must
|
|
hold for the evaluation of the system configuration to
|
|
succeed, along with associated error messages for the user.
|
|
'';
|
|
};
|
|
|
|
};
|
|
|
|
config = {
|
|
|
|
# This option is evaluated always. Thus the assertions are checked as well. hacky!
|
|
environment.systemPackages =
|
|
if [] == failed then []
|
|
else throw "\nFailed assertions:\n${concatStringsSep "\n" (map (x: "- ${x}") failed)}";
|
|
|
|
};
|
|
|
|
}
|