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| author | Maxim Cournoyer <maxim.cournoyer@gmail.com> | 2022-08-24 14:40:38 +0200 |
|---|---|---|
| committer | Maxim Cournoyer <maxim.cournoyer@gmail.com> | 2022-08-24 22:34:45 -0400 |
| commit | 1c803e63f9560b93afeec9f7342f4413ff3cec46 (patch) | |
| tree | 0482d40b846cdd02303d2cb89b2f1ed5150ce0ae /gnu/services/configuration.scm | |
| parent | 31339f5f5ffd80f3fca9dbe49990fa3be4234bb5 (diff) | |
services: configuration: Add a 'maybe-value-set?' procedure.
* gnu/services/configuration.scm (maybe-value-set?): New procedure.
* doc/guix.texi (Complex Configurations): Document it. Remove comment showing
usage of 'maybe-string' with a default value, which doesn't make sense.
Co-authored-by: Attila Lendvai <attila@lendvai.name>
Diffstat (limited to 'gnu/services/configuration.scm')
| -rw-r--r-- | gnu/services/configuration.scm | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/gnu/services/configuration.scm b/gnu/services/configuration.scm index 3007e8de35..e2c4fe9998 100644 --- a/gnu/services/configuration.scm +++ b/gnu/services/configuration.scm @@ -57,6 +57,7 @@ serialize-configuration define-maybe define-maybe/no-serialization + maybe-value-set? generate-documentation configuration->documentation empty-serializer @@ -142,7 +143,8 @@ does not have a default value" field kind))) (id #'stem #'serialize-maybe- #'stem)))) #`(begin (define (maybe-stem? val) - (or (eq? val 'unset) (stem? val))) + (or (not (maybe-value-set? val)) + (stem? val))) #,@(if serialize? (list #'(define (serialize-maybe-stem field-name val) (if (stem? val) @@ -260,11 +262,10 @@ does not have a default value" field kind))) (default-value-thunk (lambda () (display '#,(id #'stem #'% #'stem)) - (if (eq? (syntax->datum field-default) - 'unset) + (if (maybe-value-set? (syntax->datum field-default)) + field-default (configuration-missing-default-value - '#,(id #'stem #'% #'stem) 'field) - field-default))) + '#,(id #'stem #'% #'stem) 'field)))) (documentation doc)) ...)))))))) @@ -300,6 +301,10 @@ does not have a default value" field kind))) (define (empty-serializer field-name val) "") (define serialize-package empty-serializer) +(define (maybe-value-set? value) + "Predicate to check whether a 'maybe' value was explicitly provided." + (not (eq? 'unset value))) + ;; A little helper to make it easier to document all those fields. (define (generate-documentation documentation documentation-name) (define (str x) (object->string x)) |