emacs: Separate package location code.

* emacs/guix-base.el (guix-directory, guix-read-directory)
(guix-set-directory): Move to "guix-backend.el".
(guix-find-location, guix-package-location, guix-edit): Move to...
* emacs/guix-location.el: ... here.  New file.
* emacs/guix-ui-package.el: Use it.
* emacs.am (ELFILES): Add it.

1 files changed, 23 insertions, 1 deletions

diff --git a/emacs/guix-backend.el b/emacs/guix-backend.el
index 8afbc9ed48..6341aacae1 100644
--- a/emacs/guix-backend.el
+++ b/emacs/guix-backend.el
@@ -82,7 +82,7 @@ If you have a slow system, try to increase this time."
   :type 'string
   :group 'guix-repl)
 
-(defcustom guix-after-start-repl-hook ()
+(defcustom guix-after-start-repl-hook '(guix-set-directory)
   "Hook called after Guix REPL is started."
   :type 'hook
   :group 'guix-repl)
@@ -337,6 +337,28 @@ additional internal REPL if it exists."
   (geiser-repl--switch-to-buffer (guix-get-repl-buffer internal)))
 
 
+;;; Guix directory
+
+(defvar guix-directory nil
+  "Default directory with Guix source.
+If it is not set by a user, it is set after starting Guile REPL.
+This directory is used to define package locations.")
+
+(defun guix-read-directory ()
+  "Return `guix-directory' or prompt for it.
+This function is intended for using in `interactive' forms."
+  (if current-prefix-arg
+      (read-directory-name "Directory with Guix modules: "
+                           guix-directory)
+    guix-directory))
+
+(defun guix-set-directory ()
+  "Set `guix-directory' if needed."
+  (or guix-directory
+      (setq guix-directory
+            (guix-eval-read "%guix-dir"))))
+
+
 ;;; Evaluating expressions
 
 (defvar guix-operation-buffer nil