On Tue, Feb 20, 2018 at 1:48 PM Drew Adams <drew.adams@oracle.com> wrote:

> Suggestion: use functions for manipulating file/dir names.
>
> Use (file-name-directory (directory-file-name (expand-file-name file)))
>

Thank you. I was aware of that, but was just being plain lazy.. I didn't
consider refactoring my whole config to fix that until now[1], so thanks :)

Here's the improved code:

(let* ((bin-dir (when (and invocation-directory
                           (file-exists-p invocation-directory))
                  (file-truename invocation-directory)))
       (prefix-dir (when bin-dir        ;Because bin-dir = prefix-dir +
"bin/"
                     (file-name-directory (directory-file-name bin-dir))))
       (share-dir (when (and prefix-dir
                             (file-exists-p prefix-dir))
                    (file-name-as-directory (expand-file-name "share"
prefix-dir))))
       (emacs-dir (when (and share-dir
                             (file-exists-p share-dir))
                    (file-name-as-directory (expand-file-name "emacs"
share-dir))))
       (version-dir (when emacs-dir
                      ;; Possibility where the lisp dir is something like
                      ;; ../emacs/26.0.50/lisp/.  If `emacs-version' is
x.y.z.w,
                      ;; remove the ".w" portion.  Though, this is not
needed
                      ;; for emacs 26+, and also will do nothing in that
case.
                      ;;
http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=22b2207471807bda86534b4faf1a29b3a6447536
                      (let* ((version (replace-regexp-in-string
"\\([0-9]+\\.[0-9]+\\.[0-9]+\\).*" "\\1" emacs-version))
                             (version-dir-1 (file-name-as-directory
(expand-file-name version emacs-dir))))
                        (if (file-exists-p version-dir-1)
                            version-dir-1
                          ;; Possibility where the lisp dir is something
like
                          ;; ../emacs/25.2/lisp/.  If `emacs-version' is
x.y.z,
                          ;; remove the ".z" portion.
                          (setq version (replace-regexp-in-string
"\\([0-9]+\\.[0-9]+\\).*" "\\1" emacs-version))
                          (setq version-dir-1 (file-name-as-directory
(expand-file-name version emacs-dir)))
                          (when (file-exists-p version-dir-1)
                            version-dir-1)))))
       (lisp-dir (file-name-as-directory (expand-file-name "lisp"
version-dir))))
  (defvar modi/default-share-directory (when (file-exists-p share-dir)
                                         share-dir)
    "Share directory for this Emacs installation.")
  (defvar modi/default-lisp-directory (when (file-exists-p lisp-dir)
                                        lisp-dir)
    "Directory containing lisp files for the Emacs installation.

This value must match the path to the lisp/ directory of the
Emacs installation.  If Emacs is installed using
--prefix=\"${PREFIX_DIR}\" this value would typically be
\"${PREFIX_DIR}/share/emacs/<VERSION>/lisp/\"."))

I think it would be useful to include the share/ and lisp/ dirs stored in
some variable in emacs core, just like invocation-directory.

[1]:
https://github.com/kaushalmodi/.emacs.d/commit/64b0c3fbf3372bd96a32d1f24d9adeb9112abd08
-- 

Kaushal Modi