It will be convenient to bind the below function to a key binding of your choice.
If you are currently working on a
FILE buffer, calling the below function will toggle between
FILE's major-mode specific *scratch* buffer called
*scratch-MAJOR-MODE* and the
Given the example in question, if I am working on a Perl script called
myperl.pl, calling this function will toggle between
(defun modi/switch-to-scratch-and-back (&optional arg)
"Toggle between *scratch-MODE* buffer and the current buffer.
If a scratch buffer does not exist, create it with the major mode set to that
of the buffer from where this function is called.
COMMAND -> Open/switch to a scratch buffer in the current buffer's major mode
C-0 COMMAND -> Open/switch to a scratch buffer in `fundamental-mode'
C-u COMMAND -> Open/switch to a scratch buffer in `org-mode'
C-u C-u COMMAND -> Open/switch to a scratch buffer in `emacs-elisp-mode'
Even if the current major mode is a read-only mode (derived from `special-mode'
or `dired-mode'), we would want to be able to write in the scratch buffer. So
the scratch major mode is set to `org-mode' for such cases.
Return the scratch buffer opened."
(if (and (or (null arg) ; no prefix
(= arg 1))
(string-match-p "\\*scratch" (buffer-name)))
(let* ((mode-str (cl-case arg
(0 "fundamental-mode") ; C-0
(4 "org-mode") ; C-u
(16 "emacs-lisp-mode") ; C-u C-u
;; If the major mode turns out to be a `special-mode'
;; derived mode, a read-only mode like `help-mode', open
;; an `org-mode' scratch buffer instead.
(t (if (or (derived-mode-p 'special-mode) ; no prefix
(format "%s" major-mode)))))
(buf (get-buffer-create (concat "*scratch-" mode-str "*"))))
(funcall (intern mode-str)) ; http://stackoverflow.com/a/7539787/1219634