ui: Factorize command-line + env. var. option parsing.

* guix/ui.scm (%default-argument-handler, parse-command-line): New
  procedures.
  (environment-build-options): Make private.
* guix/scripts/archive.scm (guix-archive)[parse-options,
  parse-options-from]: Remove.  Use 'parse-command-line' instead.
* guix/scripts/build.scm (guix-build): Likewise.
* guix/scripts/environment.scm (guix-environment): Likewise.
* guix/scripts/package.scm (guix-package): Likewise.
* guix/scripts/system.scm (guix-system): Likewise.
* tests/ui.scm (with-environment-variable): New macro.
  ("parse-command-line"): New test.

1 files changed, 27 insertions, 1 deletions

diff --git a/guix/ui.scm b/guix/ui.scm
index 382b5b1e0d..09cb6f48ff 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -66,7 +66,7 @@
             string->generations
             string->duration
             args-fold*
-            environment-build-options
+            parse-command-line
             run-guix-command
             program-name
             guix-warning-port
@@ -754,6 +754,32 @@ reporting."
   "Return additional build options passed as environment variables."
   (arguments-from-environment-variable "GUIX_BUILD_OPTIONS"))
 
+(define %default-argument-handler
+  ;; The default handler for non-option command-line arguments.
+  (lambda (arg result)
+    (alist-cons 'argument arg result)))
+
+(define* (parse-command-line args options seeds
+                             #:key
+                             (argument-handler %default-argument-handler))
+  "Parse the command-line arguments ARGS as well as arguments passed via the
+'GUIX_BUILD_OPTIONS' environment variable according to OPTIONS (a list of
+SRFI-37 options) and return the result, seeded by SEEDS.
+Command-line options take precedence those passed via 'GUIX_BUILD_OPTIONS'.
+
+ARGUMENT-HANDLER is called for non-option arguments, like the 'operand-proc'
+parameter of 'args-fold'."
+  (define (parse-options-from args)
+    ;; Actual parsing takes place here.
+    (apply args-fold* args options
+           (lambda (opt name arg . rest)
+             (leave (_ "~A: unrecognized option~%") name))
+           argument-handler
+           seeds))
+
+  (append (parse-options-from args)
+          (parse-options-from (environment-build-options))))
+
 (define (show-guix-usage)
   (format (current-error-port)
           (_ "Try `guix --help' for more information.~%"))