Question

Several emacs extensions create “junk” buffers, and I have to manually remove them from various buffer lists.

Emacs has a concept of “hidden buffers”, which is used for instance for the minibuffer.

How can I make an arbitrary buffer a hidden buffer?

Answer 1

Emacs does have a concept of uninteresting/hidden buffers – and designates them as such by making their names begin with a space. See the documentation for buffer names. You can make a buffer “uninteresting” by changing its name to begin with a space.

Try M-x make-buffer-uninteresting:

(defun make-buffer-uninteresting ()
  "rename the current buffer to begin with a space"
  (interactive)
  (unless (string-match-p "^ " (buffer-name))
    (rename-buffer (concat " " (buffer-name)))))