Emacs: How do I create a new "empty" buffer whenever creating a new frame?

Question

My Emacs is on OS X system. Is there any way to make a new frame defaulted to an empty buffer whenever I use ⌘N (just like the way TextEdit works)? I prefer to write contents first and decide an appropriate filename later. However, Emacs wants me to decide the filename first and write contents later. I don't see any advantage for it. Does anyone know why Emacs works that way?

Basically, if I use C-x 5 2, Emacs always pops up a frame with whatever file I am currently working on. This is inconvenient. I also don't want my Emacs to pop up a new frame defaulted to *scratch* (many Google search results somehow suggest this approach). I prefer it to have a buffer temporarily called "Untitled" in the new frame, and if I use ⌘N again, Emacs pops up another temporarily "Untitled 2" buffer, and so on. In this way, I can decide the buffer filenames later.

Answer 1

You can create new buffers with switch-to-buffer. Type C-x b, enter a buffer name, and press RET. If no buffer with that name exists, Emacs creates a new one automatically in Fundamental Mode. You may switch to any other mode as usual with M-x, e.g. M-x python-mode. To change the default buffer, set the default value of major-mode to the desired buffer.

If you'd like to have a buffer name chosen automatically, and create a new frame, however, you need to write your own command:

(defun lunaryorn-new-buffer-frame ()
  "Create a new frame with a new empty buffer."
  (interactive)
  (let ((buffer (generate-new-buffer "untitled")))
    (set-buffer-major-mode buffer)
    (display-buffer buffer '(display-buffer-pop-up-frame . nil))))

Bind this to C-c n:

(global-set-key (kbd "C-c n") #'lunaryorn-new-buffer-frame)

Now pressing C-c n creates a new frame with a new empty buffer named “untitled” where x is a consecutive number.

Answer 2

The following will create a buffer with a unique name. The buffer is not associated with any file, so if/when you ever C-x C-s save-buffer, you will be prompted to supply a filename.

(defun empty-frame ()
  "Open a new frame with a buffer named Untitled<N>.

The buffer is not associated with a file."
  (interactive)
  (switch-to-buffer-other-frame (generate-new-buffer "Untitled")))