Question

I was trying some code from Elisp Cookbook, and I initially tought that this code:

 (defun process-file (file)
   "Read the contents of a file into a temp buffer and then do
 something there."
   (when (file-readable-p file)
     (with-temp-buffer
       (insert-file-contents file)
       (goto-char (point-min))
       (while (not (eobp))
       ;; do something here with buffer content
         (forward-line)))))

Will create a new ( unnamed/unsaved ) buffer on my emacs window, having the contents of that file ( and maybe open it in the foreground ). However, this doesn’t happen. Can you guide me towards this?

EDIT: I experimented a little, and got to this:

(defun myTest (file)
    (interactive "f")
    ; check if file is readable
    (when (file-readable-p file)
        ; create a new "untitled" buffer 
        (let ((myBuf (get-buffer-create "untitled")))
            ; make it the current displayed buffer
            (switch-to-buffer myBuf)
            (insert "Hello"))))         

Is this the way to do it?

Since this is a buffer named “untitled”, I can only have one of these in a session. Is there something I could use to have more than one, without resorting to random numbers?

Answer 1

The elisp way to generate a unique buffer name is to use generate-new-buffer-name. The documentation is:

(generate-new-buffer-name NAME &optional IGNORE)

Return a string that is the name of no existing buffer based on NAME.
If there is no live buffer named NAME, then return NAME. Otherwise
modify name by appending `’, incrementing NUMBER (starting at
2) until an unused name is found, and then return that name. Optional
second argument IGNORE specifies a name that is okay to use (if it is
in the sequence to be tried) even if a buffer with that name exists.