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, 2 insertions, 15 deletions

diff --git a/guix/scripts/build.scm b/guix/scripts/build.scm
index 07ced30484..370c2a37ff 100644
--- a/guix/scripts/build.scm
+++ b/guix/scripts/build.scm
@@ -405,25 +405,12 @@ arguments with packages that use the specified source."
 ;;;
 
 (define (guix-build . args)
-  (define (parse-options)
-    ;; Return the alist of option values.
-    (append (parse-options-from args)
-            (parse-options-from (environment-build-options))))
-
-  (define (parse-options-from args)
-    ;; Actual parsing takes place here.
-    (args-fold* args %options
-                (lambda (opt name arg result)
-                  (leave (_ "~A: unrecognized option~%") name))
-                (lambda (arg result)
-                  (alist-cons 'argument arg result))
-                %default-options))
-
   (with-error-handling
     ;; Ask for absolute file names so that .drv file names passed from the
     ;; user to 'read-derivation' are absolute when it returns.
     (with-fluids ((%file-port-name-canonicalization 'absolute))
-      (let* ((opts  (parse-options))
+      (let* ((opts  (parse-command-line args %options
+                                        (list %default-options)))
              (store (open-connection))
              (drv   (options->derivations store opts))
              (roots (filter-map (match-lambda