Re: Add a way to disable serialization support to (guix services configuration)

[Ludovic Courtès]

Hi Maxim,

Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:

> I've rediscovered the little gem that is (guix services configurations),
> and attempted to make it more generally useful by adding an option to
> opt out of serialization (which is not well adapted for producing a list
> of command line arguments from the configuration for example):

In the meantime I saw you discuss this on #guile so maybe you’ve solved
the issue now?

If not, attached is a possible solution and example.  It’s not perfect:
in the example, you’ll get a warning about ‘serialize-integer’ being
unbound, which is completely harmless but suboptimal.  Not sure how to
address that.

HTH!

Ludo’.

diff --git a/gnu/services/configuration.scm b/gnu/services/configuration.scm
index 90f12a8d39..20e1647335 100644
--- a/gnu/services/configuration.scm
+++ b/gnu/services/configuration.scm
@@ -109,6 +109,9 @@
              (define (serialize-maybe-stem field-name val)
                (if (stem? val) (serialize-stem field-name val) ""))))))))
 
+(define-syntax-parameter configuration-field-serialization?
+  (identifier-syntax #t))
+
 (define-syntax define-configuration
   (lambda (stx)
     (syntax-case stx ()
@@ -123,7 +126,8 @@
                            #'(field-type ...)))
                      ((field-serializer ...)
                       (map (lambda (type)
-                             (id #'stem #'serialize- type))
+                             #`(and configuration-field-serialization?
+                                    #,(id #'stem #'serialize- type)))
                            #'(field-type ...))))
            #`(begin
                (define-record-type* #,(id #'stem #'< #'stem #'>)
@@ -152,6 +156,16 @@
                                            #,(id #'stem #'stem #'-fields))
                    conf))))))))
 
+(define-syntax-rule (without-field-serialization definition)
+  (syntax-parameterize ((configuration-field-serialization?
+                         (identifier-syntax #f)))
+    definition
+    #t))
+
+(without-field-serialization
+  (define-configuration foo
+    (bar (integer 123) "doc")))
+
 (define (serialize-package field-name val)
   "")