Switch to buffer local env var modification instead of global setenv.

1 files changed, 67 insertions, 35 deletions

diff --git a/guix-shell.el b/guix-shell.el
index bf5640f..61478c9 100644
--- a/guix-shell.el
+++ b/guix-shell.el
@@ -20,15 +20,15 @@
   "Project environment variable cache.")
 
 (defun guix-shell--current-directory ()
-  (project-root (project-current)))
-
-(defvar guix-shell--hooks '(post-command-hook before-hack-local-variables-hook)
-  "Hooks that guix shell should hook into.")
-
-(defvar guix-shell--last-directory nil
-  "The last directory used for running guix shell.")
+  "Return the project directory for the current buffer."
+  (let ((project (project-current)))
+    (if project
+        (project-root project)
+      default-directory)))
 
 (defun guix-shell--search-paths-for-directory (directory)
+  "Execute 'guix shell' in DIRECTORY, parse the output, and return
+an alist of search path environment variables."
   (let ((buffer (get-buffer-create "*guix-shell-temp*"))
         (names '()))
     (with-current-buffer buffer
@@ -77,51 +77,83 @@
         env-vars))))
 
 (defun guix-shell--update-search-paths-for-directory (directory)
+  "Refresh the cached 'guix shell' search paths for DIRECTORY."
   (when directory
     (let ((search-paths (guix-shell--search-paths-for-directory directory)))
       (setq guix-shell--search-paths
-            (cons (cons directory search-paths)
+            (cons (cons directory (or search-paths 'none))
                   (assoc-delete-all directory guix-shell--search-paths)))
       search-paths)))
 
 (defun guix-shell--cached-search-paths-for-directory (directory)
+  "Return an alist of 'guix shell' search paths cached for
+DIRECTORY.  If there are no cached search paths, nil is returned.
+If the search paths are cached but DIRECTORY has no 'guix shell'
+search paths present, 'none' is returned.."
   (cdr (assoc directory guix-shell--search-paths)))
 
+;; From envrc.el
+(defun guix-shell--merged-environment (process-env pairs)
+  "Make a `process-environment' value that merges PROCESS-ENV with PAIRS.
+PAIRS is an alist obtained from direnv's output.  Values from
+PROCESS-ENV will be included, but their values will be masked by
+Emacs' handling of `process-environment' if they also appear in
+PAIRS."
+  (append (mapcar (lambda (pair)
+                    (format "%s=%s" (car pair) (cdr pair)))
+                  pairs)
+          process-env))
+
 (defun guix-shell--apply-search-paths (search-paths)
-  (dolist (pair search-paths)
-    (let ((name (car pair))
-          (search-path (cdr pair)))
-      (setenv name search-path)
-      (when (string-equal name "PATH")
-        (setq exec-path (append (parse-colon-path search-path)
-                                (list exec-directory)))))))
+  "Apply SEARCH-PATHS to the environment of the current buffer."
+  (setq-local process-environment
+              (guix-shell--merged-environment process-environment search-paths))
+  (setq-local exec-path (append (parse-colon-path (getenv "PATH"))
+                                (list exec-directory)))
+  (when (derived-mode-p 'eshell-mode)
+    (setq-local eshell-path-env path)))
 
 (defun guix-shell--apply-search-paths-for-directory (directory)
-  ;; TODO: What if the search paths have been updated and need to be
-  ;; re-applied?  This doesn't account for that case currently.  The only way
-  ;; to update would be to switch to a buffer in a different project and then
-  ;; change back.
-  (when (and directory
-             (not (string-equal directory guix-shell--last-directory)))
-    (guix-shell--apply-search-paths
-     (or (guix-shell--cached-search-paths-for-directory directory)
-         (guix-shell--update-search-paths-for-directory directory)))
-    (setq guix-shell--last-directory directory)))
+  "Set search path environment variables from 'guix shell' for
+DIRECTORY."
+  (when directory
+    (let ((search-paths
+           (or (guix-shell--cached-search-paths-for-directory directory)
+               (guix-shell--update-search-paths-for-directory directory))))
+      (unless (eq search-paths 'none)
+        (guix-shell--apply-search-paths search-paths)))))
 
 (defun guix-shell--apply-search-paths-for-current-directory ()
+  "Set search path environment variables from 'guix shell' in the
+context of the current directory."
   (guix-shell--apply-search-paths-for-directory (guix-shell--current-directory)))
 
-(defun guix-shell-enable ()
-  (interactive)
-  (dolist (hook guix-shell--hooks)
-    (add-hook hook #'guix-shell--apply-search-paths-for-current-directory)))
-
-(defun guix-shell-disable ()
-  (interactive)
-  (dolist (hook guix-shell--hooks)
-    (remove-hook hook #'guix-shell--apply-search-paths-for-current-directory)))
+(defun guix-shell--clear (buffer)
+  "Remove any effects of `guix-shell-mode' from BUFFER."
+  (with-current-buffer buffer
+    (kill-local-variable 'exec-path)
+    (kill-local-variable 'process-environment)
+    (kill-local-variable 'eshell-path-env)))
 
 (defun guix-shell-update ()
+  "Update the search paths set by 'guix shell'."
   (interactive)
   (guix-shell--update-search-paths-for-directory
-   (guix-shell--current-directory)))
+   (guix-shell--current-directory))
+  (guix-shell--clear (current-buffer))
+  (guix-shell-apply-search-paths-for-current-directory))
+
+;;;###autoload
+(define-minor-mode guix-shell-mode
+  "A local minor mode in which environment variables are set by
+'guix shell'."
+  :init-value nil
+  (if guix-shell-mode
+      (guix-shell--apply-search-paths-for-current-directory)
+    (guix-shell--clear (current-buffer))))
+
+;;;###autoload
+(define-globalized-minor-mode guix-shell-global-mode guix-shell-mode
+  (lambda ()
+    (unless (or (minibufferp) (file-remote-p default-directory))
+      (guix-shell-mode 1))))