Unverified Commit 4a56b265 authored by Naïm Favier's avatar Naïm Favier
Browse files

lib/options: nullable mkPackageOption 

It is sometimes useful to allow setting a package option to `null` to
skip installing the package. See
https://github.com/nix-community/home-manager/pull/3668#issuecomment-1554044171
for example.
parent 8d25ab1f

lib/options.nix

+14 −7
Original line number Diff line number Diff line
@@ -155,6 +155,8 @@ rec { 
      # Name for the package, shown in option description

      name:

      {

        # Whether the package can be null, for example to disable installing a package altogether.

        nullable ? false,

        # The attribute path where the default package is located (may be omitted)

        default ? name,

        # A string or an attribute path to use as an example (may be omitted)
@@ -164,19 +166,24 @@ rec { 
      }:

      let

        name' = if isList name then last name else name;

      in mkOption ({

        type = with lib.types; (if nullable then nullOr else lib.id) package;

        description = "The ${name'} package to use."

          + (if extraDescription == "" then "" else " ") + extraDescription;

      } // (if default != null then let

        default' = if isList default then default else [ default ];

        defaultPath = concatStringsSep "." default';

        defaultValue = attrByPath default'

          (throw "${defaultPath} cannot be found in pkgs") pkgs;

      in mkOption {

      in {

        default = defaultValue;

        defaultText = literalExpression ("pkgs." + defaultPath);

        type = lib.types.package;

        description = "The ${name'} package to use."

          + (if extraDescription == "" then "" else " ") + extraDescription;

        ${if default != null then "default" else null} = defaultValue;

        ${if example != null then "example" else null} = literalExpression

      } else if nullable then {

        default = null;

      } else { }) // lib.optionalAttrs (example != null) {

        example = literalExpression

          (if isList example then "pkgs." + concatStringsSep "." example else example);

      };

      });



  /* Like mkPackageOption, but emit an mdDoc description instead of DocBook. */

  mkPackageOptionMD = pkgs: name: extra: