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authorLudovic Courtès <ludo@gnu.org>2020-07-20 23:19:37 +0200
committerLudovic Courtès <ludo@gnu.org>2020-07-20 23:25:10 +0200
commit4071879c86d059ee087c8986915ea72b8c742b72 (patch)
tree77000d6c3d93ae4e486acba764dfee86986633d8 /guix
parent59a47fb67853dd28891376fc970699f11c0f972f (diff)
json: Re-export 'define-json-mapping' from (json) when available.
This prepares for the migration to Guile-JSON 4.3.0. * guix/json.scm (define-as-needed): New macro. (define-json-mapping): Use 'define-as-needed' instead of 'define-syntax-rule'.
Diffstat (limited to 'guix')
-rw-r--r--guix/json.scm31
1 files changed, 26 insertions, 5 deletions
diff --git a/guix/json.scm b/guix/json.scm
index 20f0bd8f13..3e3a28b749 100644
--- a/guix/json.scm
+++ b/guix/json.scm
@@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2018, 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -18,15 +18,33 @@
(define-module (guix json)
#:use-module (json)
- #:use-module (srfi srfi-9)
- #:export (define-json-mapping))
+ #:use-module (srfi srfi-9))
;;; Commentary:
;;;
;;; Helpers to map JSON objects to SRFI-9 records. Taken from (guix swh).
+;;; This module is superseded by 'define-json-mapping' as found since version
+;;; 4.2.0 of Guile-JSON and will be removed once migration is complete.
;;;
;;; Code:
+(define-syntax define-as-needed
+ (lambda (s)
+ "Define the given syntax rule unless (json) already provides it."
+ (syntax-case s ()
+ ((_ (macro args ...) body ...)
+ (if (module-defined? (resolve-interface '(json))
+ (syntax->datum #'macro))
+ #'(eval-when (expand load eval)
+ ;; Re-export MACRO from (json).
+ (module-re-export! (current-module) '(macro)))
+ #'(begin
+ ;; Using Guile-JSON < 4.2.0, so provide our own MACRO.
+ (define-syntax-rule (macro args ...)
+ body ...)
+ (eval-when (expand load eval)
+ (module-export! (current-module) '(macro)))))))))
+
(define-syntax-rule (define-json-reader json->record ctor spec ...)
"Define JSON->RECORD as a procedure that converts a JSON representation,
read from a port, string, or hash table, into a record created by CTOR and
@@ -48,8 +66,11 @@ following SPEC, a series of field specifications."
(symbol->string 'field))))))
(ctor (extract-field table spec) ...)))))
-(define-syntax-rule (define-json-mapping rtd ctor pred json->record
- (field getter spec ...) ...)
+;; For some reason we cannot just have colliding definitions of
+;; 'define-json-mapping' (that leads to a build failure in users of this
+;; module), hence the use of 'define-as-needed'.
+(define-as-needed (define-json-mapping rtd ctor pred json->record
+ (field getter spec ...) ...)
"Define RTD as a record type with the given FIELDs and GETTERs, à la SRFI-9,
and define JSON->RECORD as a conversion from JSON to a record of this type."
(begin