CODEWITHSUNDEEP
emacsbufferhook
Nacht
Nacht

Reputation: 11366

Emacs: load-file .emacs when saved

I'm new to emacs and lisp.

I wanted to auto-load the dot file when it was saved. Meaning, when I save my .emacs file, it would automatically call load-file on it (thus letting me know right away if I messed up).

But I can't seen to be able to find a comprehensive tutorial on hooks in emacs.

This is what I've come up with:

(defun load-init-after-save ()
  "After saving this file, load it"
  (if (eq bname this) ('load-file this) (nil))
)
(add-hook 'after-save-hook 'load-init-after-save)

Of course, this is incorrect: bname and this are just placeholders. And I don't want this function to run on all saves, just when the .emacs file is saved.

Does anyone know how to do this? Is there a better, easier way?

Upvotes: 1

Views: 416

Answers (2)

abo-abo
abo-abo

Reputation: 20362

Way 1

One way of doing is to install auto-compile-mode from MELPA, and enable it:

(defun my-emacs-lisp-hook ()
  (auto-compile-mode 1))

(add-hook 'emacs-lisp-mode-hook 'my-emacs-lisp-hook)

Now each time you save an Elisp file that's byte-compiled, it will be re-compiled. Compilation will usually catch some bad errors.

To compile any Elisp file, select it in dired (C-x d) and press B (dired-do-byte-compile).

Way 2

Use this custom code I wrote.

(defun test-emacs ()
  (interactive)
  (require 'async)
  (async-start
   (lambda () (shell-command-to-string "emacs --batch --eval \"(condition-case e (progn (load \\\"~/.emacs\\\") (message \\\"-OK-\\\")) (error (message \\\"ERROR!\\\") (signal (car e) (cdr e))))\""))
   `(lambda (output)
      (if (string-match "-OK-" output)
          (when ,(called-interactively-p 'any)
            (message "All is well"))
        (switch-to-buffer-other-window "*startup error*")
        (delete-region (point-min) (point-max))
        (insert output)
        (search-backward "ERROR!")))))

(defun auto-test-emacs ()
  (when (eq major-mode 'emacs-lisp-mode))
  (test-emacs))

(add-hook 'after-save-hook 'auto-test-emacs)

This will start a new Emacs instance in the background each time you save a file. If something goes wrong, it will complain. The second approach uses async.

If you really want to do this just for .emacs user this:

(defun auto-test-emacs ()
  (when (and (eq major-mode 'emacs-lisp-mode)
             (equal (file-truename user-init-file)
                    (expand-file-name
                     buffer-file-truename)))
    (test-emacs)))

Upvotes: 2

user355252
user355252

Reputation:

The following code loads your .emacs or ~/.emacs.d/init.el file after save:

(defun my-load-user-init-file-after-save ()
  (when (string= (file-truename user-init-file)
                 (file-truename (buffer-file-name)))
    (let ((debug-on-error t))
      (load (buffer-file-name)))))

(add-hook 'after-save-hook #'my-load-user-init-file-after-save)

Since your intended use is error-checking, the code also enables the debugger while loading the init file, so that you get a nice backtrace in case of errors.

For error checking of your init file you may also find Flycheck useful. It checks your init file on the fly with the byte compiler, highlights any errors and warnings in the buffer, and—optionally—gives you a list of all errors and warnings.

Disclaimer: I'm the maintainer of this library.

Upvotes: 4

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