Re: Adding major-mode selection to new buffer

[Jean Louis]

* carlmarcos--- via Users list for the GNU Emacs text editor 
<help-gnu-emacs@gnu.org> [2022-06-28 01:51]:
> With the following function I can make a new buffer with a name.  Would also 
> like to set the major-mode from the minibuffer.
> 
> Perhaps using `completing-read` 
> 
> (cseq '("sh-mode" "emacs-lisp-mode" "org-mode" "f90-mode" "c-mode" ))
> (csel  (completing-read "Major Mode: " cseq nil t "org-mode"))
> 
> How can I introduce the above functionality in the `workbench' function?
> 
> (defun workbench (&optional name)
>   "Make new buffer with unique name based on NAME."
>   (interactive "s Buffer Name: ")
>   (switch-to-buffer
>    (generate-new-buffer
>     (if (string-blank-p name) "wb" name))))

I am using this below to open up new temporary buffers with name
assigned or with automatic name, and with the possibility to choose
the major mode.

{C-u M-x rcd-temp-buffer RET} will ask for mode to be used

{M-x rcd-temp-buffer RET}} will open new temporary buffer

{M-x rcd-temp-buffer RET}} will open new temporary buffer

{M-x rcd-temp-buffer-ask-name RET} will ask for buffer name

{C-u M-x rcd-temp-buffer-ask-name RET} will ask for buffer name and
for the mode

Code:

(defvar rcd-temp-buffer-name "RCD TEMPORARY BUFFER")

(defvar rcd-temp-file-directory "~/tmp/")

(defvar rcd-temp-buffer-mode-history nil)

(defvar rcd-temp-buffer-modes '(("adoc-mode" . "adoc")
                                ("emacs-lisp-mode" . "el")
                                ("lisp-mode" . ".lisp")
                                ("markdown-mode" . ".md")
                                ("org-mode" . "org")
                                ("sql-mode" . "sql")
                                ("fundamental-mode" . "txt")
                                ("html-mode" . "html")))

(defun rcd-temp-buffer (&optional name mode)
  "Generate new temporary buffer."
  (interactive "p")
  (let* ((format (concat "*" rcd-temp-buffer-name "%s%s*"))
         (buffer (if name (format format ": " name) (format format "" "")))
         (file-name (concat rcd-temp-file-directory (format-time-string 
"%Y-%m-%d-%H:%M:%S.txt"))))
    (switch-to-buffer (generate-new-buffer buffer))
    (setq buffer-file-name file-name)
    (if current-prefix-arg
        (let* ((mode (completing-read
                      "Mode: "
                      (map-keys rcd-temp-buffer-modes) nil t nil
                      'rcd-temp-buffer-mode-history)))
          (funcall (intern mode)))
      (funcall (intern (or mode "fundamental-mode"))))
    buffer-file-name))

(defun rcd-temp-buffer-ask-name ()
  "Generate new temporary buffer by asking for buffer name."
  (interactive)
  (rcd-temp-buffer
   (read-from-minibuffer "Buffer name: ")))

(global-set-key (kbd "<f5>") #'rcd-temp-buffer)

-- 
Jean

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