2

In Emacs by default there is a large file warning threshold. I would prefer to instruct Emacs never to open files of a certain type or size. These are files I would prefer always to open in an external application. I now have it set up that I can use the shortcut key C-RET to open a file in an external application. Sometimes however I accidentally press RET and Emacs prompts me as to whether I would like to open the file. My preferred response would be for Emacs to do nothing, not even to prompt me. Otherwise, I would prefer to always open the type in the default external app.

2

It sounds like you want this only for interactive use, i.e., a command.

Define your own substitute for command find-file (or find-file-other-window etc.). Have you command check the file size, using functions file-attributes and file-attribute-size, and refuse to open the file if it is bigger than some threshold you set.

For example (untested):

(defvar my-find-file-max-size 100000
  "Max size for `my-find-file'.")

(defun my-find-file (file &optional wildcards)
  "`find-file`, unless FILE is > `my-find-file-max-size' bytes."
  (interactive (find-file-read-args "Find file: " (confirm-nonexistent-file-or-buffer)))
  (when (> (file-attribute-size (file-attributes file))) (error "File %s is too big" file))
  (find-file file wildcards))
0

I am grateful to @Drew for also providing me with similar code for Emacs Dired. With it, clicking on a large file in Dired will result in a message about the file being too big to open.

(defun my-dired-find-file ()

  "Like `dired-find-file', but raise error file is too big."

  (interactive)

  (let ((find-file-run-dired t)

        (switch-to-buffer-preserve-window-point

         (if dired-auto-revert-buffer

             nil

           switch-to-buffer-preserve-window-point))

        (file  (dired-get-file-for-visit)))



    ;; Check file size, and raise error if too big.

    (when (> (file-attribute-size (file-attributes file))

             large-file-warning-threshold)

      (error "File %s is too big" file))

    (find-file file)))

(define-key dired-mode-map [remap dired-find-file] 'my-dired-find-file)

The size of the file will depend here on the value of the variable large-file-warning-threshold.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.