Cache PATH and env vars. fetched with exec-path-from-shell

See updated documentation in this commit.

doc/DOCUMENTATION.org

@@ -94,6 +94,7 @@
     - [[#layout-key-bindings][Layout key bindings]]
   - [[#workspaces][Workspaces]]
     - [[#workspace-key-bindings][Workspace key bindings]]
+- [[#environment-variables-and-path-from-the-shell][Environment variables and PATH from the shell]]
 - [[#commands][Commands]]
   - [[#vim-key-bindings][Vim key bindings]]
     - [[#escaping][Escaping]]
@@ -1716,6 +1717,24 @@ There are also some handy globally available key bindings related to workspaces:
 | ~gT~        | go to previous workspace             |
 | ~SPC b W~   | go to workspace and window by buffer |
 
+* Environment variables and PATH from the shell
+When using the Emacs GUI environment variables defined by your shell may not
+be available to the Emacs process. This is especially true for macOS.
+
+The command to fetch the environment variables from your shell is very expensive
+and increases the startup time quite a lot.
+
+For this reason, Spacemacs caches the PATH value and some environment variables
+in the file located at =~/.emacs.d/.cache/.env-vars=.
+
+Any environment variables that are not found are still written to the cache file
+with the value =<VAR>-NOTFOUND-PLEASE-DEFINE-IN-YOUR-SHELL=.
+
+Spacemacs won't update the cached values by itself, if you want to update your
+shell variables then either delete the cache file or execute the interactive
+function =spacemacs/import-path= and restart Emacs to fetch any updated
+environment variables.
+
 * Commands
 ** Vim key bindings
 Spacemacs is based on =Vim= modal user interface to navigate and edit text. If

layers/+distributions/spacemacs-bootstrap/config.el

@@ -81,3 +81,6 @@ if used there.")
                                  ("iedit-insert" "firebrick1" (bar . 2)))
   "Colors assigned to evil states with cursor definitions.
 To add your own, use `spacemacs/add-evil-curosr'.")
+
+(defvar spacemacs-env-vars-file (concat spacemacs-cache-directory ".env-vars")
+  "Cache file for exec-path variable.")

layers/+distributions/spacemacs-bootstrap/funcs.el

@@ -183,8 +183,38 @@ Example: (evil-map visual \"<\" \"<gv\")"
 
 
 
+;; exec-path-from-shell
+
+(defun spacemacs//initialize-exec-path-from-shell (&optional force)
+  "Initialize exec-path and cache its value.
+Load from cache file if cache file exists and FORCE is nil."
+  (when (display-graphic-p)
+    (when force (delete-file spacemacs-env-vars-file))
+    (if (file-exists-p spacemacs-env-vars-file)
+        (load spacemacs-env-vars-file nil (not init-file-debug))
+      (require 'exec-path-from-shell)
+      (exec-path-from-shell-initialize)
+      (spacemacs/dump-vars-to-file '(exec-path) spacemacs-env-vars-file))))
+
+(defun spacemacs/import-path ()
+  "Import value of PATH."
+  (interactive)
+  (spacemacs//initialize-exec-path-from-shell t))
+
 (defun spacemacs/copy-env-list (vars)
-  "Copy list of env. VARS using `exec-path-from-shell'."
+  "Copy list of env. VARS using `exec-path-from-shell'.
+Cache the found value in `spacemacs-env-vars-file'."
   (dolist (var vars)
-    (unless (getenv var)
-      (exec-path-from-shell-copy-env var))))
+    (unless (or (getenv var)
+                (null (configuration-layer/package-used-p
+                       'exec-path-from-shell)))
+      (require 'exec-path-from-shell)
+      (exec-path-from-shell-copy-env var)
+      (with-temp-file spacemacs-env-vars-file
+        (insert-file-contents spacemacs-env-vars-file)
+        (print (list 'setenv var
+                     (if (getenv var)
+                         (getenv var)
+                       (format "%s-NOTFOUND-PLEASE-DEFINE-IN-YOUR-SHELL"
+                               var)))
+               (current-buffer))))))

layers/+distributions/spacemacs-bootstrap/packages.el

@@ -287,8 +287,7 @@
   (evil-declare-ignore-repeat 'spacemacs/previous-error))
 
 (defun spacemacs-bootstrap/init-exec-path-from-shell ()
-  (require 'exec-path-from-shell)
-  (exec-path-from-shell-initialize))
+  (spacemacs//initialize-exec-path-from-shell))
 
 (defun spacemacs-bootstrap/init-hydra ()
   (require 'hydra)