I have an option that must be left with the default value when a certain flag (another option) is false.
I didn’t find any example (let alone documentation) on how to implement this, so I’ve come up with two ideas:
option-that-errors-out-if-set-when-flag-is-false =
let
default = if config.some-flag
then "some default value for when flag is true"
else "value that should not be changed when flag is false";
in lib.mkOption {
type = lib.types.str;
inherit default;
apply = v: assert assertMsg (config.some-flag || v == default) "Do not set this option unless 'flag' is true";
v;
};
option-that-ignores-value-when-flag-is-false =
let
default = if config.some-flag
then "some default value for when flag is true"
else "value that should not be changed when flag is false";
in lib.mkOption {
type = lib.types.str;
inherit default;
apply = v: if config.some-flag then v else default;
};
Which one do you think is “best” (cleaner, more idiomatic, etc…)?
Is apply
the “right” place to validate options? Should I make a custom type instead? Should I approach this in some different way?
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You probability want to use assertions